Use of Models for Water Resources Management, Planning ... · construction of dams, reservoirs, and water treatment facilities. Mathematical models are becoming increasingly important

Use of Models for Water ResourcesManagement, Planning, and Policy

August 1982

NTIS order #PB83-103655

Library of Congress Catalog Card Number 82-600556

For sale by the Superintendent of Documents,U.S. Government Printing Office, Washington, D.C. 20402

Foreword.

9

‘Director

iii

The Nation'. water resource policies, affect many problem. in the ~$tates today-food production, energy, regional economic development, enviro:,"quality, and even our international balance of trade. As the country grows, and ~. ,. _ "'I water supplies diminish, it becomes increasingly important to manage existing sup~th the greatest possible efficiency. In re~ent years, successfull11anagement andplanniag of water resources has increasingly been based on the results ,of mathematical~~.:

~~;

Leaving aside the mystique of computers and ~pl~_ mathe~atics, mltematical models are simply tools used for understaIJ.ding w~~f~8odIc. and ",at~ re_e management activities. This part of water resource manaFm.~~ii thou~ not as apparent as dams and reservoirs or pipes and sewers, is a vital cOlripcmetif inIDetltiJ;lg tlriW'l ation' s water resource needs. Sophisticated analysis, through the ute of models, can improve our understanding of water resources and wat~r resource activities, and helpprev~ wasting both water and money. -

This assessment of water resource models is therefore 'DOt an assessment Of_'$ tical equations or computers, but of the Nation's ability t~ Use models to more e.·' tly and

effectively analyze and solve our water resource prob~,m .. :, I •. ~rn-. ' .. :", ',.,e ~ a:'~e, ssment :',.,' •. ,:. rs not only the usefulness of the technology-the models-but _ability of Feder -,.,.' State water resource agencies to apply these analytic too1a ~~ly ..... ,' " : ':;;~~::;i

The capabilities of water resource models vary ~ ~'~to ilalue. In. number of areas, further research and development is needed, but ~n~t am.s, usable", reliable tool. currently exist. However, as often occurs, these ~ba!C'OU.~ the capabilities of Federal, State, and local agencies ,to ~pport and effectively u' ',. Today, model use is increasing the efficiency and lowering'the cost ofwaterresou " :'. agement, but the potential for further improvementtemains great.~1'~:

This report presents options that focus on ways of improving Federal, State-~-.,nd local use of available technologies to analyze water raOurce problems. Opportunities.~ identified for congressional action to improve water retOUcce management capabilitifl\-dtrough selective model use-throughout the Federal Government, within individual Fedlbl agencies, and among State and local governments. The importance of water resource" to the Nation's well-being, ,and the magnitude ofpotenti~ water resource problems in the coming decades, makes this technqlogy an important tool for ~suring our ability to provide for the water needs of cu~nfand future generations. ,;,,' I

About 40 water resources professionals from Federal andState agencies, universities, and the private sector contributed, to this report~Many more provided useful cp~ments on draft materials. OTA was all9,aided by ~ntativ~8 from 27 Federal agencies and offices, and from all 50 States, w~o providedin(oimation in response to OT A surveys and inquiries regarding model use, as well as by·Fed.eral, ·university, and private sector participants in two series of workshops on modeling issues. OT A expresses sincere appreciation to all these individuals for helping bring ~~~I amount of collective wisdom to this analysis. It~', :. ;1:, .• ' ., ::'

Contributors to This Report

David AlleeCornell UniversityMary AndersonUniversity of Wisconsin, MadisonNeil ArmstrongUniversity of Texas at AustinJohn BredehoeftU.S. Geological Survey

James ChalmersMountain West Research, Inc.

Jared CohonJohns Hopkins UniversityCharles FaustGeoTrans, Inc.A. J. FrederickPrivate consultant

James GeraghtyGeraghty & MillerWarren HallColorado State UniversityJames HeanyUniversity of FloridaWayne HuberUniversity of Florida

Richard HydeHolcomb Research Institute

L. Douglas JamesUtah State UniversityWilliam JohnsonU.S. Army Corps of EngineersWilliam LaneBureau of Reclamation

Arun MalikJohns Hopkins UniversityJames MercerGeoTrans, Inc.

Ronald NorthUniversity of GeorgiaDonald O’ConnorManhattan CollegeJohn PetersU.S. Army Corps of EngineersCharles ReVelleJohn Hopkins University

Richard RibbensBureau of ReclamationDonald RobeyU.S. Army Corps of EngineersLeonard ShabmanVirginia Polytechnic Institute

Daniel SheerInterstate Commission on the Potomac River Basin

Soroosh SorooshianCase Western Reserve UniversityClair StalnakerU.S. Fish and Wildlife ServiceRoland SteinerJohns Hopkins UniversityJames ThomasBureau of ReclamationHarry TornoU.S. Environmental Protection AgencyRichard TuckerDames & Moore

Andrew WaldoNational Counsel Associates, Inc.Porter WardU.S. Geological SurveyWalter WunderlichTennessee Valley AuthorityJeffrey WrightJohns Hopkins University

OTA appreciates the assistance of many additional people who contributed to this report:●

●

●

●

Participants in the two OTA water resource modeling workshops.Federal agency personnel who responded to the OTA Federal agency survey.State agency personnel who responded to the OTA State agency survey, and directors of the State water resourcesresearch institutes who suggested appropriate respondents.The professional societies that reviewed technical materials, including the American Geophysical Union, theAmerican Society of Civil Engineers, the American Water Resources Association, and the National WaterWell Association.

OTA Water Resource Models Assessment Staff

John Andelin, Assistant Director, (ITAScience, Information, and Natural Resources Division

Robert W, Niblock, Oceans and Environment Program Manager

Project Staff

Robert M. Friedman, Project Director

Chris Ansell, Research AssistantStuart Diamond, * Writer/Editor

Nancy Ikeda, Policy Analyst

Yacov Y. Haimes, Consultant

Administrative Staff

Kathleen A. Beil Linda G. Wade Jacquelynne R. Mulder

OTA Publishing Staff

John C. Holmes, Publishing Officer

John Bergling Kathie S. Boss Debra M. Datcher Joe Henson

● OTA contract personnel

. -----.-- +, .-. .-,.-

1-.Contents

I‘ .

i

Chapter1.

2.

3.

4.

5.

6.

A.

B.

c.D.

E.

Summary, Issues, and Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction to Water Resource Models . . . . . . . . . . . . . . . . . . . . . . .

General Issues in Model Development, Use, and Dissemination . .

Federal Use and Support of Water Resource Models

Use of Models by State Governments . . . . . . . . . . . . ./Modeling and Water Resource Issues . . . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .I

, --Sumpary of Model Use by Individual Federal Agencies, . . . . . . . .

Summaries of Related Modeling Studies . . . . . . . . . . . . . . .’. . . . . . . .

Additional References to Models and Model~g Sm% ~”” “ “”” ● o

.* . , .***.

.* . . .***.

. . . . . . . . .

. . . . . . . . .{. . . . . . . . .

.,. . . . . . ,.. . ..

AppendixSummary of Findings from OTA Workshops on Water Resource Modem

Zig:. . . . . * * * .

. . . . . . . . .

. * . , , . * , .

Tables of Responses to OTA Survey of State-Level~Model Use. . . . . . . . . . . .

.

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ● . “ . * .

.

.

.

.

.

.

.

.

.

.

.

.

Pqe3

25

47

67

97

119

165

172

199

202

216

237

.

i/ ,

i

.

—

Chapter 1

Summary, Issues, and Options

[, ,

Scope . . . . . . . . . . . . . . ....4.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . ............-...:., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -

Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “Issue 1. Improving Federal Problem-SolvIssue 2. Meeting the N’eeds of the States

ng Capabilities , . . . . . . . . . . . . . . . . . ...,., . . . . . . . . . . . . . . . . . . . . . . . . ..,,

Issue 3. Establishing Appropriate Modeling Strategies Within IndividualFederal Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Issue 4. ProvidiIssue 5, Federal

n,g Potential Users With Information About Existing Models .Support for Model-Related Training . . . . . . . . . . . . . . . . . . .

I

—

Chapter 1

Summary, Issues, and Options

SCOPE ‘. . .’,., ‘, . - . . ’

t“ , .— ,

This assessment is intended as a guide for Con- .The full report includes:., J.. , .

)

.

— — —

4 ● Use of Mode/s for Water Resources Management, Planning, and Policy

INTRODUCTION

Between 1950 and 1975, the Federal Govern-ment spent over $45 billion to develop, maintain,and improve the Nation’s water resources; 1 expend-itures have spiralled to even higher levels over thepast decade. Federal efforts range from construc-ting dams to increase the reliability of water sup-plies, generate hydroelectric power, improve floodcontrol, and provide recreational opportunities; tostudies for determining whether flood plain areasare sufficiently safe to permit building activities;to providing wastewater treatment for reducinghealth and environmental risks due to pollutedrivers, streams, and lakes.

Decisions affecting water resources are made bythe Federal, State, and local governments, and bythe private sector. These decisions include design-ing day-to-day management procedures for oper-ating facilities most efficiently, as well as planningand implementing long-range policies for water re-sources management and construction. Decisionsof the latter kind involve large sums of money, andmay affect the availability and quality of water formany decades to come. As the Nation grows, andexcess water resource capacities diminish, itbecomes increasingly important to manage existingfacilities, improve the efficiency of water use, andmake long-range plans in ways that maximize thereturn on natural, capital, and human resources.

Mathematical models are among the most so-phisticated tools available for analyzing waterresource issues. They can use the capabilities oftoday’s digital computers to perform and integratemillions of calculations within seconds, in order tounderstand and project the consequences of alterna-tive management, planning, or policy-level activ-ities. Models only assist in decisionmaking—theyprovide information that people must interpret inlight of existing laws, political and institutionalstructures, and informed professional and scientificjudgment. Nonetheless, models can significantlyimprove the informational background on whichdecisions are based, and substantially reduce the

‘Viessman, et al., 7%e Nation Water Outlook to the Year 2000. The$45 billion estimate includes expenditures by the Army Corps ofEngineers, the Bureau of Reclamation, the Soil Conservation Serv-ice, the Tennessee Valley Authority, and the Environmental Protec-tion Agency’s Construction Grants Program outlays.

cost of managing water resources. Although theFederal Government spends approximately $50million on water-related mathematical models an-nually, such tools are instrumental in planningbillions of dollars of annual water resource in-

Photo credit: Environmental Protection Agency

Photo credit: U.S. Depaflment of Agriculture

Federal, State, and local governments, and the privatesector, provide billions of dollars to support theconstruction of dams, reservoirs, and water treatmentfac i l i t ies . Mathemat ica l models are becomingincreasingly important in determining the need for suchfacilities, and in planning, designing, and operating them.Models can be used to help operate existing structuressuch as the McNary Dam on the Columbia River (top),as well as to develop and run new facilities like the

illustrated water purification system inDuncan, Okla. (bottom)

Ch. 7—Summary, Issues, and Options . 5— —

vestments, and managing hundreds of billions ofdollars of existing facilities.

The role of models in managing water resourceshas grown dramatically over the past decade—aperiod in which water resource management itselfhas become increasingly important. High rates ofeconomic and population growth in water-shortareas of the country, decreased availability of waterfrom major ground water aquifers, and increasedpublic concern for the quality of its drinking water,lakes, and rivers have made it even more necessaryto manage water resources carefully. In addition,the issue of who is to manage water resources hasgained prominence in the political arena, as waysare sought to increase States’ responsibilities forassuring adequate and safe water supplies.

The magnitude of the national investment inwater resources calls for systematic use of the bestanalytic tools available to manage this investment.Over the past 20 years, models and sophisticateddata processing systems have been advanced aspromising great improvements in water resourcesmanagement, planning, and policy. Yet many con-sider that these tools have not yet lived up to earlierexpectations. OTA was requested to study the useof models in freshwater resources analysis in orderto determine their current capabilities, identify ap-propriate roles for their use, and suggest optionsfor improving modeling efforts and model use.

Photo credits; :’ Ted Spiege/, 1982

Pipelines to provide new supplies of water for the Stateof Arizona (top) and the New York City water tunnel (bot-tom) demonstrate the magnitude of the Nation’s waterresource needs. Reliable forecasts of an area’s water re-quirements are critical for designing efficient and ade-quate water transport and distribution systems. Modelscan be used to estimate future demands for water, and

to assist in water system design

FINDINGS

Mathematical models have significantly ex-panded the Nation’s ability to understand andmanage its water resources. They are currentlyused to investigate virtually every type of water re-source problem; for small- and large-scale studiesand projects; and at all levels of decisionmaking.In some cases, models have increased the ac-curacy of estimates of future events to a level farbeyond “best judgment” decisions. In other areas,they have made possible analyses that could not

be performed empirically or without computerassistance. Further, models have made it feasibleto quantitatively compare the likely effects of alter-native resource decisions. A few examples of situa-tions in which models have been applied will il-

lustrate their uses:

● Water in excess of amounts needed by cropsis often applied to fields to leach out ac-cumulated salts. This results in high water use

/

e ● use of MOOE;S tor Water Resowces Management, Planning, and Pollcy. . - . ..- . -- - .

,

e

●

●

,.and high salt loadings in irr”iga&o~~ flowsreturned [(} streams. New hlexico scientists de-veloped ii ‘ ? to estimwe the, ,[)m uter r~l<j, ~:Pminimum a)~lount of lea~ iilng water ~cquiredto maint~in crop yields and favorable soilsalinities. The model has resulted in annualsavings in lifter costs of $.’l~0,000 for the PecosRiver bas ;~ in New MexiLJ. In addition, thelower irri~i~[ion return flows have reduced thesalt input i(~ the Pecos I? ~’.wr by 235,000 tonsper year.The Clear~ Water Act curi(:ntly requires’~clis~chargers to Aneet effluent---or ‘end-of-pipe’ ‘—standards. and, in addition, to discharge nomore of iJ. ) ‘(~llutant tha~-, w~eiving waters+?nsafely C(if : v ~ according u; a fixed receivl~gwater qui~ilt~ standard. Models are an @@@tive means of projecting :1 (e rec~”ivimg W@’quality lhc.t results from different leveh. bfdischarge. and are thus ;~ major aid in deter+mining WIIA[ levels of discharge are peivnissi-ble unchr ~ ~’eiving vat(’, :~andar~l’For the l~~)~thern Virginia area, 197/ ;vas thedriest year since 1950. The Occoquan Reser-voir servinv northern Virqinia was nearlyempty, ai-i; ! daily withdr:i’”, JS exc~>~:~t:d daily

inflows. I_rsing its extended streamflow predic-tion moclel, the National Weather Service(NWS) determined that there was a lo-percentrisk of reaching emergency reservoir knds-arisk deerr~; ~ I unacceptable by local authorities.The model was then used to project that anacceptable 2- to 3-pereent risk of reachingemergency reservoir le~-els would require re-ducing J$ ithdrawals by about 20 percent.3 4

Reserv(~i~s are usual]> multiple-purpose facil-ities, m,. ~ i Y“ UJ whose [J!) it’~t i ~~? ‘I . conk[ or co~n-pete. Rcstrvoir mana~ers need to retain suffi-cient wtit(’r to ensure an adequate future sup-ply for users, yet must release enough for floodcontrol ~Ur~(JSes, M \\’Cll ZM t(-) ensure ZKkqUate

low-flow levels to protect aquatic life and minim-ize the cost of pollution control downstream.

‘Impacts of the L’ni~(rsi~ Water Resear~h Program, Task ~’or~c on Re-search and Education in Water Resources, U.S. Department of theInterior, March 1981, p. 9.

3D. C. Curtis andJ. C. Schaake, Jr., ‘‘The Nationat Weather Serv-ice Extended Sttiamflow Technique. ” Conference on Reservoir Sys-teni Regulation, ASCE, Boulder, ~do., ~{lg. 14-17. 1979.

41). P. Sheer, “Analyzing the Risk of Drought: The Occoquan Ex-perience,’’Journa/ of the A&an Water J4’orks Association, May 1980.

Additional objectives include maximizing hy-dropower production (by releasing water) andrecreational opportunities (retaining water forreservoir lake users, and releasing water forstream and downstream lakti users). Mathe-matical models’,have been used on many of theNatipn’s major river systems to address con-fi”~ ti~e demands by suggesting optimalarn~nf~’ and timing of reservoir releases.

,~: ~~ ‘~@@@y investigators developed a‘ ~-opt;fitititionmcthdtodesi~asewer:.

~=#!&if~r ~hb Long Island Regional Plan-‘ ~ @tn=~%a~di.: The resulting analysis indicated

!‘ th~~~~~+wer tietiyork that would meet commu-‘“&&&@s edut~-be built and operated for $40

z rniIIi& @ss’&@;cc@f a design developed by~ ~~~~~ug~~vcti.~on~ ~n~ytic~ ~ethods. s

Mu&i. have the potential to provid&@# ,greater benefits for water resource decisionmak-ing in the future. As models are refined andreceive wider acceptance, they will be able to in-crease the efficiency of water resource manage-ment ~ eacourage cost-effective decisionmak-ing. Such rnodeis can do much to increase the ra-L imm.lity of regulations and [he standard-settingprocess, and can generally provide a sound scien-tific basis fa water policy. The following examplesillustrate ~g, potential benefits of’ f’uture expansioni~~ m~~&@~: ~ ‘

-=+ ~ :3 ;: : .● &.49k ad 1975, the Tennessee Valley

Au@~, (TVA) spent over $2 billion for~!&&~tir:es development and manage-=~~~ovmg rainfall forecasting and reswpVt&$t?kxh.tling can make a very significazitcontribution to the benefits that accrue fromthese water development projects. Recent

szmpacts of t~ university Water Research Progam, OP. cit., P. 4.

Ch. l-Summ6vy, Issues, and Options ● 7I

I

stuches on six TVA reservoirs found the poten-tial for a 20-percent improvement in opera-tions and annual savings of $4 million through~\]{: ;mplenlcntation of a s~stcm of reser~roi’rscheduling models. G

.NWS estimated that tht~ installation of a~?fi~,ooo” ?n{}deling systenl m forecast floodson !Ike Connectictlt River basin would providea reduction in flood damages exceeding $1.5million per year.7Nfcdels assist farmers in scheduling irrigz.ticm.sto optimize water conservation while md-intain-ing crop productivity. In INebraska, improvedirrigation scheduling has resulted in 25- to35-percent savings in water pumped #nd cfwy-~>’ (. CJsts pCX” year. 8 ;1 ,,t; ,i,

Water resource models vary greatly i~&&capab~ !ities and limitations arid must be ciirehd+ly selected and used by knowledgeable pro&- ‘sionals, Some models are designed for manage-i]~t:iit ~~ithin small watersheds; others are uked in

, for la C[W> ~ 7 fl n i ‘ ‘ ge~-~~raphic:ll areas. Some are;if~sigyle~ I [o prm’icie highly accurate rN.@ufic? ~~+tin-mtes; others will provide only gene@ appt-@c-imations. some models are designed for dtuat~ohsi~ J whit. ~: data arc scarce: other r~mdels require largeamounts of data. h some instances, decisionrna.kersneed only “ballpark” accurac)’ to make decisions,hll! in Orher instances mo(iel accuracy may be ex-

trcmcly important. A clecisionmaker may rccjuire:1 differc~nt mod{’] in each case, even tlmugh similiarkinds of problems are being analyz~d~

Since modeling is a rapidly advancing and highlyspecialized field. it is extremely diffi~~:for deci-sionmakers and managers to stay abre~t of newdevelopments, or ev(’n to fully unc$’&tan(l i hecapabilities and limitations of the toolh’ they cur-rently employ. Under suc~- circu~start~es; ‘a;c~r?tain amount of model misuse and rqis~~ust is; vir-tllally inevitable. A manager who t~~~. a, gi~~n~node] to analyz( a si? uation it was n~~, tlf:d~:~edto address; or who overrelies on” the accuracy”of———

“’~”. Xl. Wunderlich, ‘‘Plannwl Enhanremerit of Mratcr hlanage- ~••rnent Methods for the TVA Reservoir System, paper pxesermd atthe National Workshop on Reservoir Systems Operation, AmerkanSociety for Civil Engineers, Aug. 13-17, 1979.

‘H. J. Day and K. K. Lee, ‘(Flood Damage Reduction Potential~)! R i~w’r Forecast Servicrs in the Connecticut River Basin, .\lf~ ~ ~‘J’echnical Memorandum NWS HYDRO-28, February 197

81mpuct~ of the Uniwmlty Water Rc~earch Program, op. cir. , p. . .

- credit: C Ted Spiegel, ?982Agriculture account$ for ovw 80 percent of U.S. wateruse. Critical shortages of water for irrigation in manyareas of the country make models for w Iudulir’jirrigation a valuable tool for stretching lhY$fed andincreasingly expensive supplies. Th6$&~odelsdetermine when plants requip water, and how.,@#fr.theywill need; same can estimate reductions !rt c~-$ yields

if ifrlgatfcm is delayed or reduced ~ ‘: -.. ...-. .,.“.

often the method of choice to meet the require-ments of ledslation. Many current laws regarding+, aler resources require antiyucai work normtuly1:’”~,. 1 11 lr . - , .

. - , . - , ” . A Gti Ll usa . .

8 ● Use of Models for Water Resources Management, Planning, and Policy

legislation associated with model use at Federal,State, or local levels includes:

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

Clean Water Act (Public Law 95-217)—sections 107, 201, 208, 209, 301, 302, 303,307, 311, 314, 316, 404, and 405;Safe Drinking Water Act (Public Law 93-523)—sections 1412, 1421, 1422, 1424, 1443, and1444;Toxic Substances Control Act (Public Law 94-469)—sections 4, 5, and 6;Resource Conservation and Recovery Act(Public Law 94-580)–sections 1008 and 8006;Endangered Species Act (Public Law 93-205)—section 7;Surface Mining Control and Reclamation Act(Public Law 95-87)–sections 506, 510, and515;Soil and Water Resource Conservation Act(Public Law 95-192)–sections 5 and 6;Water Resources Planning Act (Public Law89-80)—section 102;Coastal Zone Management Act (Public Law94-370)—section 305;Executive Order No. 11988 (Floodplain Man-agement);Flood Control Act of 1936 and Amendments—sections 1, 2, and 3;National Flood Insurance Act of 1968—section73;Water Research and Development Act (PublicLaw 95-467)—section 1360;Federal Reclamation Act of 1902 and Amend-ments—43 U.S.C. 421 and 422;National Environmental Policy Act (PublicLaw 91-190)—sections 102 and 103; andAtomic Energy Act of 1954—10 CFR 20, 50,61.

In translating legislative requirements intomanagement practices, agencies often recom-mend procedures that depend on the use ofmodels. The Clean Water Act, for instance, re-quires States to determine the “total maximumdaily loads” for those sources of pollutants that can-not meet water quality standards through effluentlimitations regulations. This requires States topredict the water quality resulting from a numberof point-source loadings—a responsibility that im-plicitly requires the use of ‘wasteload allocation’models. EPA’s Waste Load Allocation Guidance

Memorandum (Sept. 5, 1979) strongly encouragesthe use of models for performing wasteload alloca-tions. The memo reads:

The link between wasteload allocations andstream standards is a mathematical model to pre-dict water quality as a function of waste discharges.Such models exist and are integral parts of themethodology. 9

9’ ‘Funding of W’astc Load Allocations and Water Quality Anatysesfor POTW Decisions, Construction Grants Program RequirementsMemorandum, U.S. Environmental Protection Agcnc), PRNI No.79-11, Sept. 5, 1979, “Preliminar) Technical Guidance for W’LAStudies, ” p. 4

Photo credit: r Ted Spiegel, 1982

Models are important tools for determining whetherindividual point-sources of water pollution will preventrivers, lakes, and streams from meeting Federal waterquality standards. Using models, planners can determinewhat levels of discharge would be acceptable beforetreatment facilities are insta//ed; such information is

extremely valuable for designing effectivetreatment strategies

Ch. l—Summary, Issues, and Options ● 9

Developing and using models is a complexundertaking, requiring personnel with highlydeveloped technical capabilities, as well as ade-quate budgetary support for computer facilities,collecting and processing data, and numerousadditional support services. Such capabilitiespresently reside primarily within the FederalGovernment, or are secured from the private sec-tor with Federal funding. For fiscal year 1979,direct and indirect Federal expenditures in sup-port of model development, dissemination, anduse for water resources are estimated at $40million to $50 million annually. The Army Corpsof Engineers, the U.S. Geological Survey (USGS),and the Environmental Protection Agency (EPA)are the principal agencies involved in water resourcemodeling activities, and together they account forapproximately 70 percent of the funds spent in sup-port of water modeling at the Federal level. Theseexpenditures represent an ongoing investmentin information that supports and improves ex-penditures of billions of dollars annually forwater resource development and management.

Federal training and assistance is also importantin assuring the continuing availability of hydrolo-gists, engineers, and modelers with expertise inwater resource issues. The demand for well-trainedwater resource professionals at Federal, State, andlocal government levels, as well as in the privatesector, far exceeds the number of individuals whograduate annually with relevant skills from Amer-ican colleges and universities. Federal support foruniversity-level research and training, through theUniversity Water Research Program of the Depart-ment of the Interior, amounted to about $11 millionin fiscal year 1980. In addition, a number of Federalagencies offer important training opportunities inwater resources analysis and modeling for Federaland non- Federal employees alike. While such train-ing is often critical for keeping professional employ-ees abreast of developments in these fields, currentlevels of instruction are clearly insufficient to meetthe growing needs of Federal, State, and local per-sonnel.

Virtually all Federal modeling activities arecurrently managed on an agency-by-agency ba-sis. Little coordination of model development,dissemination, or use occurs among Federal

agencies, and effective joint modeling efforts arerare. Agencies generally have little informationabout models available through or being developedby other agencies; consequently, agencies tend todevelop new models before taking advantage of pre-vious or ongoing modeling efforts of other agen-cies. While independent agency-level developmentmay produce tools that are more responsive to spe-cific agency needs, the lack of cooperative develop-ment has often resulted in agencies being unableto muster the resources to adequately develop andsupport needed models. Testing models is a dif-ficult, expensive process and very often a major bar-rier in the way of model use. OTA found instancesin which more than one agency had developed sim-ilar models, none of which were used for lack ofadequate testing and validation.

Most Federal agencies have no overall strategyfor the development and use of models; conse-quently many legislative requirements and deci-sionmaker needs for information are not beingmet. Due to the newness and technical complex-ity of the modeling field, levels of communicationbetween decisionmakers and modelers are low,and little coordination of model development,dissemination, or use occurs within individualFederal agencies. Developers, working either asFederal employees or as private contractors, tendto have a relatively free hand in creating and usingmodels. While the independence afforded to theirdevelopment has facilitated rapid advances indesign, the lack of accountability has resulted inmodels that often fail to address decisionmakers’needs for information, require impracticalamounts of data, or are not well enough ex-plained to enable others to use them.

Successful modeling requires adequate re-sources for support services, such as user assist-ance, as well as for development. Presently,model development has outstripped correspond-ing support for models. In the past, model devel-opers have put a premium on developing models,while support for models—documentation, valida-tion, dissemination, user assistance, and mainte-nance—has been neglected. Often, resources arefocused on development, but are unavailable forsupport activities. The neglect of model support has

. ,–1 , , - P 7 - .’

10 Use of Mode/s for water Resources Management, p/annjng, and po/icy

led to a multiplicity of models, most of which areunderutilized. Many of these models cannot be usedby personnel other than the developer, due to lackof documentation, access to the model, and userassistance.

Federal agencies that have had considerable suc-cess with modeling have devoted substantial atten-tion to the problem-solving needs of potential usersand decisionmakers, and to providing adequatesupport services. These programs generally includea central responsibility for disseminating softwareand documentation, providing training and techni-cal assistance, and updating and maintainingmodels.

State governments frequently use waterresource models, although many wish to usethem more extensively than is currently possi-ble. OTA’S survey of State water resources pro-fessionals indicates that potential levels of modeluse at the State level are at least twice as highas current use levels. Technical capabilities at the

State level tend to be limited—stalls are small, andprevailing salary scales prevent many States fromhiring and/or retaining adequate numbers of per-

sonnel with modeling skills. Consequently, mostStates depend primarily on the Federal Govern-ment to provide them with suitable models,technical expertise, and training in model use.Those Federal agencies that have had considerablesuccess in.assisting States have made substantialcommitments to providing support services—USGS runs a cooperative program that currentlyassists over @Xl&ate and local agencies in develop-ing and applying models, while the Corps of En-g i n e e r s c E n g i n e e r i n g C e n t e r ( H E C )widely provides services to State and local govern-ments, an@- them in using HEC-built models.

Lack of @#&nation is a major barrier to Stateand bed’@% models~personnel are often un-aware that models for a given type of analysisalready exist. Additionally, many federally devel-oped models are inappropriate for use at the Statelevel. The specific needs of States are infrequently

&co&de@@@’ ?&k+ rn@el devdopment. Many

d

S-8$:;.% :=:= =,;~t~th~ir ‘analytic and modeling

c+a ‘ : I@%@%l l!i+ e.xpandcd if ,S(ates arf m.+-=”<a;sume ,a: -&’&l%d& iti-futllre tiatm resource &cj- .~g:.,; :

,,

The issues discussed in this section focus on thepotential to improve the Federal role in develop-ing, using, and disseminating water resource mod-els. opportunities for increasing the efficiency andeffectiveness of current model-related efforts andprograms are noted, although the general natureof the options set forth prohibit development of’specific cost estimates or estimates of the potentialsavings associated with a given option. Each op-tion presented for congressional consideration isdesigned to increase the productivity of the billionsof dollars in}’ested annuall} in wat~r resources aiidwater resource management. Issues 1 and 3, f’k- ,proving Federal Problem-Solving Capabiliti~s,,”and “Establishing Appropriate Modeling StrategiesWithin Individual Federal Agencies, ” are directedtoward making m~re effective use of the approxi-mately $50 million per year spent by the FederalGovernment on water resource modeling; issues 2,4, and 5, “Meeting the Needs of the States, ” “Pro-

. .~:-; ,+-7 . .... -r. ., .S . - . ., ,

~idm%x~&*~. uwr~ wi&ff&at\on A~uf ~- ,, ;

jsting M & & ‘ ‘ and “FMk%al Support for Moda~~Rel@#~.~i@,” focus on impro~.ing modelingcap@M1~Kkt&&.tgh the provision of augmentedmo@l-~@?t@;#&+ici#. ~, > - ..-, +, ., ,,,~ . * , .<- .., %:. ,. ,, ,

‘-’~i~~~z Improving Federal“l%6!@3&&i_Solving Capabilities..-. -4—’==. %+5 .=. += - -=,- --=-+ >Z+c: k ~ ...= ~ ;:+ . .

overall strategy for developing, using, dissemi-nating, and maintaining these tools. Models tendto be built on an ad hoc basis, in response to im-mediate problems, rather than as a result of inte-

Ch. 1-summary, Issues, and options ● 11

grated planning. In the absence of any comprehen-sive model development and support strategy, Fed-eral agencies are often unresponsive to State andFederal problem-solving needs, or to congressionaldirectives expressed in water resources legislation.

The OTA survey of Federal agencies revealsgreat variation in the use of water resource models.Although a particular law may assign similar ana-lytic responsibilities to a number of agencies, someagencies will employ the most sophisticated com-puter tools available for their analyses, while othersrely primarily on simpler approaches. In somecases, this may be all that is needed; however, inmany instances, implementation of legislative re-quirements could be improved by more sophisti-cated Federal analytic capabilities. While a fewagencies are extensively involved in developingmodeling expertise (e. g., Corps of Engineers andUSGS) most agency modeling efforts vary greatlyfrom issue to issue, from program to program, andfrom decisionmaker to decisionmaker.

Most water resource problems, and the Federallegislation that deals with them, affect a numberof Federal agencies. However, each agency is indi-vidually responsible for developing and funding theanalytic tools it requires. While many models havewidespread potential use among a variety of Federalinstitutions, it is often impossible for anyone agencyto commit the personnel and financial resourcesnecessary to bring them to completion. Develop-ing these tools is expensive and technically com-plex. For example, the problem of collecting enoughdata to fine-tune models and test their accuracy caninhibit model development by a single agency.Un-less clear direction and priority-setting mech-anisms are provided by Congress and the Exec-utive Office of the President, the best analytictools will not be available throughout the FederalGovernment, and many needed models will notbe built or supported.

At present, minimal Federal oversight existsfor the finding of applied research and develop-ment (R&D) activities. The mechanisms thatrently exist for coordinating water resources ana “-

“fins almost entirely on research needs. Neith@t%information required for solving policy problemsnor the analytic techniques needed to aid in deci-sionmaking are directly addressed in the current.

process for coordinating the Federal R&D agendain water resources. Under the water Research andDevelopment Act of 1978, the Secretary of the In-terior is presently directed to develop a 5- year waterresources research program, drawing on the exper-tise and advice of appropriate Federal agencies, theState water resources research institutes, and otherappropriate entities. The program is to indicategoals, objectives, priorities, and funding recom-mendations to the President and Congress for waterresources R&D. That document is intended to serveas the basis for funding allocations in the budgetprocesses of Congress and the Executive Office ofthe President. ,

While the 1978 act recognizes the need tostrengthen, “The capability for assessment, plan-ning, and policy-formulation , . . at the Federaland State level, “ it provides no specific directionto determine what mix of research and problem-solving capabilities can best meet Federal needs.Moreover, by concentrating primarily onresearch needs, it misdirects mission agencypriorities toward research per se rather thantoward coordinated development and utilizationof scientific knowledge and related analytic ca-pabilities. The research focus of the current actalso reinforces tendencies within individual agen-cies to fund projects that reflect the agency’s mis-sion, rather than priority problems identified byCongress and the Executive Office of the President.

Options available to Congress include:

Congress could amend the Water Researchand Developement Act of 1978 to specify the de-velopment of a multiyear plan emphasizing a

mix of R&D needs, unable analytic tools, and

supp:~ w, ,0 ~@& ~mrvices f~~ mmrring that these tools are, ... - gers.

Over a dozen reports defining Federal waterresources research needs have been prepared over

12 ● Use of Models for Water Resources Management, Planning, and policy— . — —-—-— — - — —

the last 20 years. 10 The latest of these, the NationalResearch Council review of the draft Five-YearPlan specified by the act, lists major water resourceproblems, and further states that:

For many of the foregoing problems the basicand applied research has already been accom-plished in substantial part, if not entirely. Whatis often lacking, however, is adequate technologytransfer . . . Solution of many other problems re-quires research and development to advance thestate of knowledge.

The individual agency research plans submittedfor use in developing the Five-Year Plan gave highpriority to the development of mathematical mod-els. Similarly, a 1977 report on research needsby the Committee on Water Resources Researchstated that, “Throughout this ‘catalog of neededresearch, there is a strong theme that calls for con-tinually improving mathematical and physical mod-eling capability. ‘I 1

As with previous plans, the latest Five-Year Planproposal has not been as effective as it might havebeen, due to its emphasis on a research agenda.While models have been acknowledged as impor-tant research tools, little attention has been paid todeveloping the analytic tools and support capabilityneeded to meet Federal and non-Federal water re-source problem-solving responsibilities. Majorgains in the effectiveness of Federal modeling ef-forts can be achieved through systematic provisionof such support services as assistance in locatingand obtaining usable existing models, testing andevaluating models for application to different con-ditions and decisionmaking needs, and training andtechnical assistance in using the models.

Mathematical models are an important compo-nent of the water resource analysis needs of Federalagencies. However, as with other forms of R&D,creating these tools is only the first step in estab-lishing needed analytic capabilities. Congress couldexpand the scope of the Water Research and Devel-

——~ ~~[>dela[ Walel //esOU7Ce> A Reolew oj the Propo red Flue- year %yarn

Plan, Water Rcsourccs Research Re\iew Cornmlttec, Commission onNational Rcsf)ur( es, National Rescar( h Council: National AcademyPress, 1981

18 DlrectlonJ In (J ~’ W’alo Research 1978-1982, Committee on WaterResources Research of the Federal Coordinating Council for Science,Engineering, and Technology (Springfield, Va. : National TechnicalInformation Ser\ice PB 274278, (Xtohcr 1977),

opment Act to specifically address a broader rangeof analytic and problem-solving needs for waterresources decisionmaking, and provide a mecha-nism (such as an interagency coordinating commit-tee) to carry out the intent of the act.

OPTION l-B:Congress could establish an interagency unit

whose responsibilities include developing a mul-tiyear plan for water resource analytical needsand coordinating the implementation of theplan.

Interagency representation may be necessary forsuccessful coordination. This unit might be housedeither within the Office of Science and TechnologyPolicy or in an interagency water resources policyorganization similar to the Water Resources Coun-cil or its potential successor. The unit might bedirected to work closely with the Office of Manage-ment and Budget for budgetary rev iew.

OPTION l-C:When addressing priority problems through

legislation, Congress could establish specificmechanisms to provide adequate Federal waterresource analytic capabilities to meet the intentof the legislation. .

Congress could explicitly direct Federal agenciesto provide institutional support for the analyticcapabilities needed to implement legislative goals.A number of approaches could be used for provid-ing these capabilities, including centers of excellenceat universities, operating units within existing Gov-ernment organizations, and agency and interagencydemonstration programs for creating support units.Examples of such support units as the Fish andWildlife Service Instream Flow Group are describedin chapter 4.

Issue 2: Meeting the Needsof the States

Most of the Nation’s major water resource legis-lation is based on the concept of a strong State-Fed-eral partnership for managing and planning the useand protection of the Nation’s water. If States areto fulfill their responsibilities, and take on anincreasing share of water resource managementdelegations in the future, it is in the Nation’sbest interest to ensure that the States have ac-

Ch. l—Summary, Issues, and Options ● 1 3

cess to, and are capable of using, the best avail-able analytic tools.

Many States depend heavily on Federal agen-cies for assistance in modeling, and rely primarilyon models that: 1 ) are widely available, 2) have along history of use, and 3) are well supported byFederal agencies. Most States lack the financialresources and the technical expertise required todevelop models independently. States frequentlyshare common responsibilities or problems, and cantake advantage of federally developed models de-signed for application to a wide variety of natural,social, and economic situations. Even for situationswhere differences among States require substantial-ly different models, agencies of the Federal Govern-ment are important centers of expertise to whichStates. turn for modeling assistance.

However, many of the models that Federalagencies routinely use are inappropriate to assistthe States in fulfilling their water resourcesresponsibilities. Even when agencies developmodels that relate to State concerns, they often haveno mandate to assist the States in analyzing theirwater resource problems. Consequently, manyStates find that such models are too complex to use,require more input data than States can afford tocollect, or fail to meet specific State analytical needs.

Although a few agencies, such as EPA, solicitgeneral input from the States through advisory pan-els or other means, State needs are largely ne-glected in Federal agency modeling processes.If State agencies are to utilize Federal modelsto a greater extent, practical mechanisms mustbe devised for providing State input into themodel development processes within individualFederal agencies.

In addition, for the Federal Government to beeffective in assisting States to analyze water resourceissues, it must first develop reliable means of ob-taining information about State needs. Mechanismsfor assuring State input into Federal R&D proc-esses, as specified under the Water Research andDevelopment Act of 1978, are inadequate. The cur-rent act directs the 54 State (and territorial) waterresources research institutes to develop 5-year re-search program reports in close consultation withappropriate State agencies, and to submit these tothe Secretary of the Interior for use in developing

a 5-year coordinated Federal water resources re-search program. As outlined in Issue 1, ‘ ‘Improv-ing Federal Problem-Solving Capabilities, sucha procedure focuses primarily on water resourcesresearch, and does not give adequate considerationto developing and supporting analytic tools for solv-ing important water resource problems. In addi-tion, it makes the State water resources researchinstitutes the primary liaisons between the Statesand Federal water resource planning. The in-stitutes, many of which were created by Federallegislation and operate primarily through Federalfunding, are primarily research centers.

The capacities and functions of the State waterresearch institutes vary widely, Some compete ex-tensively for discretionary Federal research funding,while others operate primarily on the small basicallocation provided to all 54 institutions. Some areactively involved in pursuing solutions to water re-source problems that affect their States, whileothers concentrate on scientific problems that mayhave few near-term practical ramifications.

Perhaps most importantly, the institutes have afederally authorized research focus that makes itdifficult for them to adequately account for the ap-plied research and problem-solving needs of Stateand local water resources agencies. While they playa vitally important role in the long-term develop-ment of expertise, the institutes are in a relativelyweak position to voice State agency needs to theFederal Government.

Two additional pressing needs identified in theOTA survey of State water resource agencies arediscussed in detail under issues 4 and 5: 1) betteraccess to information about existing models; and2) increased training opportunities in model use forState personnel.


OPTION 2-A:Congress could direct the States to designate

a lead State agency to assist the Secretary of theInterior, or other designee, in developing a mul-tiyear plan for water resource analysis needs.

The Water Research and Development Act di-rects the State water resources research institutes,in consultation with State agencies, to provide in-put to the Five-Year Plan mandated by the act. If

f4 ● use of Mode/s for water Resources Management, planning, and policy

the Federal Government is to assist States in meet-ing water-related responsibilities, it must take intoaccount a wide range of State water resource agencyinformation and analytic needs. Congress couldamend the act to allow the States to designate a leadState agency or a water resources research instituteto participate in planning a broader multiyear Fed-eral agenda.

OPTION 2-B:Congress could strengthen the States’ own

capabilities to undertake sophisticated water*source analysis.

As the States’ water resource management re-sponsibilities have increased, so have the States’ re-quirements for sophisticated water resource anal-ysis. Improving the States’ own analytic capa-bilities, either through federally sponsored train-ing or by funding the States to develop and use theirown analytic tools, could allow States to be lessdependent on Federal agencies for analysis.

For example, the Clean Water Act (Public Law95-217) directs the Administrator of EPA to makegrants to planning agencies to develop a compre-hensive water quality control plan for a river basin.Congress might consider, similar programs for waterresource development programs. If the States areto assume a greater role in the priority-setting proc-ess, Congress might consider including formulafunding to strengthen States’ analytic capabilities.

OPTION 2-C:Congress could direct Federal water resource

agencies to respond to the analytical needs ofthe States whenever States are to implementFederal programs.

For example, under the Safe Drinking WaterAct, the States have primary enforcement respon-sibility for public water systems. The act specificallydirects the Administrator of EPA to conduct re-search and demonstrations of improved methods(i) tO identify and measure the existence contam-inants in drinking water (including methods whichmay be used by State and local health and waterofficials), and (ii) to identifi the source of such con-taminants.” One activity undertaken by EPA—funding the Holcomb Ground Water Model Clear-inghouse—helps the States obtain ground waterquality models used to identify the transport andfate of pollutants.

,.4 - : .

--- — -- . . - ,

Many of the major Federal water resourceagencies lack an intergratedplan for developingand supporting models. These agencies general-

,

. Ch. l—Summary, Issues, and Options ● 15

ly develop models in response to an immediate needto solve particular problems. Few attempts havebeen made to integrate related modeling effortswithin each agency. Moreover, many models areproduced without serious attention to decision-makers’ needs or significant managerial input.Models may not have been tested to determine theirranges of error and applicability to different con-ditions, and model assumptions and results maynot be explained well enough to allow decision-makers to interpret them properly. Consequently,some agencies may have a multiplicity of models,only a few of which are actuaIIy usable.

A few Federal agencies or offices, however,have established comprehensive strategies fordeveloping and supporting models. These strat-egies generally take two different forms,: 1) develop=ing the capacity to analyze priority water resourceproblems encountered by many users, through alimited number of carefully selected models; or2) developing a general capability for analyzingindividual problems on a one-time or limited basis.Each involves different mixes of model developmentand support activities.

Outstanding examples of both modeling ap-proaches currently exist within the Federal Govern-ment. The Hydrologic Engineering Center (HEC)has extensively developed the capacity to maintainand support 12 Corps-built models. HEC supportservices include training in model use and technicalassistance to users. EPA, upon the completion ofits Stormwater Management Model (SWMM), es?tablished the SWMM Users’ Group to encouragethe model’s dissemination and use. Since its incep-tion in 1973, membership has grown to over 500users, who meet to exchange information and ideasrelating to the model's use, assist each other in run-ning it, and explore alternative analytic tools. Adescription of HEC and SWMM User Group ac-tivities is provided in chapter 4 of this report,

Developing selective modeling capabilities canbean effective strategy when frequently occur-ring priority problems appear’ to be solvablewith some kind of standard technique. Modelsfor dealing with these problems are generallydeveloped in anticipation of repeated applicationby a variety of users. Their design must give closeattention to user needs and capabilities. Models

must be thoroughly explained, or documented, testedfor use over a wide variety of conditions, easily ac-cessible, and usable on many different computerfacilities without ma@ modifications.

To assure that the models are widely and appro-priately used, the sponsoring agency must furtherdevelop a coordinated program of user supportservices, including;l) training programs—with“hands-on” instruction, if possible; 2) one-on-onetechnical assistance, for problems that arise in thecourse of running the Model and interpreting itsresults; and 3) model maintenance, to incorporateimprovements and assure that users are informedof such modifications: -, :,J s

Agency expenditures support of such a pro-gram need not be large .Services for frequently usedmodels are often provided by the private sector ona paid COnsultant basis. Agencies may need onlyto provide rudimentary services, directing users toappropriate sources of further assistance. However,the agency would need to ensure that the necessarysupport is available of the highest quality.

More general modeling capabilities have beendeveloped by USGS, which maintains a cooperativeassistance program that provides services on a cost-sharing,. to over 600 State and local agencies.To meet the requirements of these dispersed users,USGS maintains numerous models that can beadapted,.by its staff to specific local situations.USGS model-related activities are described in de-tail in chapter4 of this report. The diversity of user

ed.

ne s, particularly for ground water modeling,makes this approach particularly helpful for assist-ing non-Federal agencies lacking inhouse model-. .,ing capabilities.

For users with unique information and ana-lytic needs,developing standard models to an-

%

*Jpat.;~:2 ,= ~ needs may be inappropriate. Int$@~,SJ@#J~”$,Jri

S, strategies emphasizing general@~~@#@#~tiesS which stand in readiness~3@~@!,~~@Wt a model appropriate to eachWW#,S,##@+@~ needs , may be more effective,Such a strategy requires personel capable ofroutinely coordinating model development, bring-ing scientific knowledge and modeling expertise tobear on unique situations. While the individual

16 Use of Mode/s for Water Resources Management, planning, and policy— —

models require appropriate support (e. g., adequatetesting and documentation), the process focuses onthe needs of a single decisionmaker or decisionmak-ing group, rather than on those of many dispersedusers. Developers must work closely with the userto adapt the model to the particular issue, test andapply the model, and interpret its results.

Developing comprehensive strategies forbuilding and disseminating water resource mod-els is a pressing need for each of the Federalagencies involved in this field. Decisions on whatkinds of modeling capabilities to develop, and whatlevels of funding to allocate in support of them, needto be made at top policymaking levels within eachagency for the agency as a whole, taking into con-sideration its present and future responsibilities, andits role in providing other Federal, State, and localgovernment entities with assistance in model use.While issue 1 addressed strategies for improvinginteragency coordination of water resource model-ing activities, long-range intra-agency planning forthe models and related support services within eachagency’s purview must supplement interagency co-ordination efforts.

An option available to Congress includes:

OPTION 3-A:Congress could, through its oversight respon-

sibilities, direct each of the major Federal waterresource agencies to develop a coordinated strat-egy for the development, dissemination, and useof models.

OTA case studies indicate that coordinated plan-ning is necessary for providing effective institutionalsupport to encourage model development, dissemi-nation, and use. While the approaches used in exist-ing programs differ widely, successful efforts havetwo elements in common: 1) the models are of highquality, have been evaluated over a wide range ofconditions, and are responsive to users’ needs; and2) the models are well documented and maintained,easily accessible, and are associated with adequatetechnical assistance. Oversight activities to ensurethe development of a strategy incorporating eachof these elements could help promote a more effec-tive problem-solving capability within Federal agen-cies.

Two elements that are integral to the develop-ment of comprehensive modeling strategies—train-ing and the availability of information about models—are discussed below as issues 4 and 5.

Issue 4: Providing Potential UsersWith Information About

Existing Models

Many models currently developed by Federalagencies are intended for a single application—oncethey have been built, and are used to analyze asingle problem, they are considered to have servedtheir purpose, and are shelved. Since they are notdesigned for distribution, information on their exist-ence is not typically made available outside theagency. Consequently, other agencies with poten-tial uses for these models may be unaware that suchmodels even exist. Often the models are not testedto determine their accuracy and applicability toother situations, nor are they sufficiently docu-mented so that others may choose to use them.Models developed by outside contractors, but whichare left undocumented or are documented inade-quately, may not even be usable by other person-nel within the same agency.

No entity within the Federal Government isspecifically charged with providing informationto potential users—Federal or non-Federal—about the governmentwide availability of waterresource models. Three existing units provide suchinformation as part of a more general mission; each,however, is limited in its ability to gather compre-hensive information on existing Federal models,rapidly access that information for users, and matchuser needs to available models.

The Water Resources Scientific InformationCenter (WRSIC) has supported two major sourcesof water resource information, Selected WaterResources Abstracts, and the Water ResourcesResearch in Progress File. Both have provided ref-erence services geared to trained water resourceprofessionals— information on modeling activitiesis included, but not in a format that allows for readyaccess to specific types of models. Moreover, theservices do not reference models or documentationdirectly. They can at most identify publications in

Ch. l—Summary, Issues, and Optjons ● 1 7—...— ——— —————————— ————

which models are cited or described, or ongoingresearch projects that involve modeling activities.Recent cost-saving initiatives are projected to sub-stantially curtail WRSIC activities, particularly inthe area of printed material; however, computer-based information retrieval services for accessingpublished work are expected to be maintained.

The National Technical Information Service(NTIS) collects and sells data files, computer pro-grams, and model documentation manuals fromFederal sources. The sheer magnitude of the NTISmission— responsibility for disseminating over 1million publications—makes it extremely difficultfor NTIS to provide detailed assistance to poten-tial computer model users. Its information retrievalsystem is not well suited for locating available com-puter tapes of models. Recently, NTIS files of com-puter tapes have been combined with those of theGeneral Services Administration’s Federal SoftwareExchange Center (FSEC).

FSEC serves as a central repository for computerprograms that Federal agencies consider to be wide-ly applicable. Its holdings span an extremely widerange of subjects, and water resource models com-prise only a small portion of the available software.Since FSEC has a very limited staff, it cannot assistusers in determining the capabilities and limitationsof its models, running them, or interpreting results.Moreover, agencies provide models to the Centeron a purely voluntary basis, and FSEC regulationsprohibit the Center from identifying the agency thatdeveloped the model to potential users without theagency’s expressed consent. Lacking access to theindividuals who developed the model, users mayhave difficulty in applying it to the problems theyneed to analyze. The organization’s inability to pro-vide user support limits its primary utility to pro-fessionals with highly developed modeling expertise.

All of these organizations provide informationon models that have been documented and suppliedto them by various Federal agencies. However,many Federal models are not entered into any ofthese systems, and many that have been enteredhave been inadequately documented.

A number of attempts have also been made atagency levels to provide relatively detailed infor-mation on models dealing with specific subjectareas. Two of the larger systems dealing with water

resource concerns are the Department of Agricul-ture’s Land and Water Resources and EconomicModeling System, and the EPA Center for WaterQuality Modeling, both of which are described indetail in chapter 4 of this report.

In recent years, the concept of a model clearing-house has gained many adherents in the scientificand managerial community. Such clearinghouseswould be designed to organize models for easyaccess by users with specific analytical needs.To test the utility of the clearinghouse approach,EPA has sponsored the development of the Inter-national Clearinghouse for Ground Water Models(ICGWM) at the Holcomb Research Institute. Anextensive description of ICGWM is provided inchapter 4 of this report. Preliminary findings indi-cate that ICGWM has been very successful in im-proving the accessibility of ground water models.Clearinghouses, however, remain a controversialapproach. Some water resources professionals areskeptical of their cost effectiveness, and of any oneorganization’s ability to provide expertise aboutlarge numbers of mathematical models.

options available to Congress include:

OPTION 4-A:Congress could direct the Federal water

resource agencies to make information on agen-cy models available to outside users and to es-tablish mechanisms to distribute these modelson request.

Several water resource agencies have already es-tablished catalogs of existing models, but on thewhole, it is extremely difficult to obtain informa-tion about the existence and specifications of feder-ally developed models. This information is generally

unavailable to potential users in local, State, orother Federal agencies.

A second component of information transfer isthe dissemination of the computer program for themodel. Such programs are also generally difficultto obtain. One office with extensive capabilities fordistributing models to potential users is HEC,described in chapter 4. Congress could direct agen-cies that do not presently distribute the results offederally funded modeling activities to do so at rea-sonable cost to the user.

18 ● Use of Models for Water Resources Management, Planning, and policy

OPTION 4-B:Congress could expand the role of existing in-

formation transfer agencies to be more respon-sive to the modeling information needs of watermanagers, and encourage water resource agen-cies to use these existing mechanisms.

Either FSEC or WRSIC could be expanded toserve as a Federal Government-wide repository ofwater resource models and model information.Each of these groups currently provides limited in-formation about water resource models-FSEC fo-cuses directly on models, but has no water resource-related mission or expertise, while WRSIC is acomprehensive information source for water re-source research, with no model-related mission orexpertise. Neither provides the support services re-quired for assisting potential model users.

Water resource agencies would have to be en-couraged to assist the chosen information transferagency in expanding its services.

OPTION 4-C:Congress could establish a national clearing-

house system for the distribution of waterresource models.

Though several model clearinghouses currentlyexist in the United States, many important watermodeling areas are not covered by any existing or-ganization. The Holcomb Clearinghouse containsan extensive file of ground water models, andEPA’s newly established Center for Water Qual-ity Modeling contains information on a few of themost popular surface water quality models.

Due to the substantial interconnections and over-laps among water resource modeling activities,many professionals consider it desirable to developa comprehensive center to which a water resourcemanager could turn to obtain complete informa-tion on the availability of models. Such a centerwould bring together models developed by the Fed-eral Government, States, and the private sector.A centralized clearinghouse, or a series of clear-inghouses, containing information on models of allaspects of water resources—quality and quantityof both ground and surface waters, as well as thesocial and economic implications of water use—could assist water managers to choose amongst themultitude of available tools.

“Seed money” would be required to start a na-tional clearinghouse, but after several years ofoperation, equitably designed user fees could covera substantial portion of clearinghouse operationcosts. The clearinghouse should provide, at aminimum, information about available models. Ad-ditional services could include providing computerprograms, or more extensive services such as train-ing courses.

OPt ion 4 -D:Cogress could fund an interagency demon-

stration project to evaluate and compare exist-ing models for a representative range of fieldc o n d i t i o n s .

Though thousands of water resource models are currently available few have, been evaluated forconditions other than those under which they weredeveloped. Information about the accuracy of mod-,-els is difficult to obtain-and for many models isnonexistent. Poor validation of models is a majorcomplaint of potential users and a significant con-straint on model use.

source community professional societies might bewilling to jointly undertake the project. The resultsof these evaluations would assist professionals in, ,,.$ ~ ~;:,:choosing tools appropriate to their needs, and givedecisionmakers greater confidence nce in the results..: . . ., .,. .. - ,,.

If the demonstration program is successful, amore formal mechanis for interagency modelevaluation might be established., ::. . . ; .

interpret water resource models. However, Feder-al, State, and private sector personnel reportedthat the inadequacy of current levels of model-

.

Ch. 1-Summa#y, Issues, and Options ● 19

.

related training is a major impediment to meet-ing the needs of local, State, and Federal agen-cies. State water resource professionals consideredincreased federally sponsored training opportunitiesto be a top priority. In addition, officials of Federalagencies that sponsor training programs acknowl-edge that inadequate resources are presently pro-vided for training nonagency personnel, and thatcurrent agency training opportunities fall far shortof demand. If models are to be used effectively inwater resource analysis, training in basic conceptsof modeling and in proper interpretation of modelresults must be offered to decisionmakers at all lev-els of government. Finally, ’Federal support for theacademic training of future water resource profes-sionals has been threatened by recent cost-savinginitiatives.

There are three major aspects to model-relatedtraining: 1) general educational opportunities inwater resources research and analysis; 2) specific

training in the use of individual water resourcemodels; and 3) continuing education for manager/decisionmakers and users. Each involves a differentkind of Federal training support.

Educating water resources professionals in-volves extensive academic training and requiressupport for research and related overhead. Since1965, the Office of Water Research and Technology(OWRT) of the Department of Interior has spon-sored the University Water Research Program. Theprogram provides seed money, through the Statewater resources research institutes, for trainingstudents in water-related studies and providingequipment for students and faculty research work.Individuals who benefit from the program may be-come m&M developers, or water resources manag-ers, or analysts who use water resource models.Federal expenditures for the program amounted toapproximately $11 million for fiscal year 1980.Funding has been provided on a matching basis

(

phOtO credit: Ted Spiegel,1982

A hydrologist at USGS headquarters In Reston, Va., instructs staff in the use of one of the agency’s.streamflow models at a desktop computer terminal


with State governments, which contributed over$17 million to the institutes during the same fiscalyear. Over the past 16 years, the program has madea significant contribution to alleviating the short-age of qualifled technical manpower for water re-source management. Federal appropriations for theUniversity Water Research Program for fiscal year1982 have been reduced to approximately $6 mil-lion. The fate of the University Water ResearchProgram is still uncertain. OWRT has been sched-uled for elimination, with its responsibilities to betransferred to other offices and programs, beforethe end of the current fiscal year.

Model users require specific training to enablethem to use a particular model and apply it toactual problems. Such training is a critical com-ponent in transferring modeling technologiesfrom the developer to the organizations chargedwith solving water resource problems. Manymodels go unused, or are underused, because suchtraining is not widely available. USGS and HECare among the Federal agencies that presently con-duct training courses in model use—HEC train-ing courses reserve approximately 10 percent ofclassroom places for State and non-Corps of Engi-neers Federal personnel in 24 weeks of formal train-ing programs per year. These courses have great-ly expanded the use of HEC and USGS models,and improved the proficiency of water resource pro-fessionals in using them. While both agenciesstrongly support the concept of one-on-one train-ing and “hands-on” workshops in model use, thecost involved in providing these forms of traininglimit their present use. Using a different approachfrom that of HEC, the SWMM User’s Group pro-vides such assistance informally, or on a fee basisamong members. Use of the SWMM model hasbecome so widespread that a number of universitiesaround the country have begun to provide train-ing courses in its use; EPA has not been obligedto provide formal training instruction since the fallof 1976.

Short training courses in a number of the morewidely used models are available through publicand private universities. These courses are highlyvaluable in providing users with the informationnecessary to operate models and interpret theirresults.

Managers and decisionmakers are often unpre-pared for the problems and complications associatedwith model use for water resource problems. Manyhave completed their formal education prior to thewidespread use of computer modeling techniques,and do not understand the concepts underlyingcomputer-based simulation and analysis. Few Fed-eral agencies have yet made a significant com-mitment to decisionmaker education and re-training to accommodate modeling techniques.The Instream Flow Group currently conducts anexecutive training program to enable field person-nel and administrators to use model-based rec-ommendations; ICGWM has recently begun a se-ries of ground water modeling workshops, the mostintroductory of which discusses the application andlimitations of models for policymakers and decision-makers. Nonetheless, Federal efforts to provide con-tinuing education in model use for management-level personnel are still in very early stages.


OPTION 5-A:Congress could allocate resources to water

resource agencies specifically for establishing in-house and extramural training programs fortheir personnel, and for water managers in Stateand local agencies.

Two types of training programs are needed:1) courses on the use of specific models for poten-tial model users; and 2) continuing education formanagers and decisionmakers to understand t: estrengths and weaknesses of model-based analyses.

Several examples of training programs are de-scribed in chapter 4. These range from courses of-fered by HEC to the informal conferences ofSWMM’S Model User’s Group. While excellentexamples of training programs exist for agenciesto follow, the need for additional programs is great.

A variety of approaches could be used for devel-oping adequate training programs. Agencies couldarrange to fund training provided by universitieswith acknowledged expertise in water resourcemodeling, or develop inhouse training capabilitiesthrough agency personnel or outside contractors.

Ch. l—Summary, Issues, and Options ● 2 1

OPTION 5-B:Congress could expand the current programs

assisting university-level water resources edu-cation.

Training grants to universities, and researchgrants that provide the opportunity for students toobtain experience in analyzing water resource prob-lems, are two mechanisms by which Congress canhelp provide an adequate supply of well-trainedprofessionals.

Educating students in state-of-the-art analysistechniques, often available at universities through-out the country but not within Federal, State, andlocal agencies, brings these techniques to the agen-cies when these students graduate and are hired.Research and training programs offered throughthe National Science Foundation and OWRT areimportant mechanisms for meeting future agency-level analytical needs.

,

Chapter 2

Introduction to WaterResource Models

Contents

PageIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Introduction to Water Resource Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Water Resource Issues ● *** . . . ● **.*.** .***.... ...*...* +....... . . . . . . . 30

Case Study of Model Use: Water Resources in Long Island, N.Y. . . . . . . . . . 4 0

Tab&No.

1. Specific Resource Issues

Fipre No.

FIGURES

1. Inadequate Surface Water Supply and Related Problems..2. Surface Water Pollution Problems From Point Sources . . .3, Surface Water Pollution Problems From Nonpoint4. Ground Water Overdraft and Related Problems . .

Sources. . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

TABLE

Report . . . . . . . . . . . . . . . . . . . . . .Page

26

Page

32363738

Chapter 2

Introduction to Water Resource Models

INTRODUCTION

The Nation’s water resource policies affect manydomestic problems in the United States today—energy, the environment, food production, regionaleconomic development, and even the internationalbalance of trade. As the country grows, excess watersupplies diminish, and it becomes increasingly im-portant to manage existing supplies with the great-est possible efficiency. Americans are demandingmore water—and cleaner water—for households,industry, agriculture, energy development, recrea-tional use, and aquatic life. For many areas of thecountry, the availability of adequate water suppliesis a limiting factor in residential construction,agricultural production, and economic developmentin general.

As the Nation approaches full utilization of itswater resources, water resource management is be-coming more complex. Different kinds of uses, anduser groups, increasingly compete for limited sup-plies. Moreover, interconnections among virtual-ly all aspects of water systems are increasinglyapparent— stream flows affect underground reser-voirs, for example, while manmade civil works,laws, and relations have profound consequencesfor the hydrologic balances of entire regions.

Thus, the ability to manage and plan the use ofAmerica’s water resources—and determine the con-sequences of resource decisionmaking-becomes in-creasingly important and increasingly difficult aswell. In recent years, successful management andplanning has increasingly been based on the resultsof mathematical models. The information providedby these tools is used to help make such decisionsas funding flood control structures, planning pollu-tion control programs, or operating water supplyreservoirs.

Leaving aside the mystique of computers andcomplex mathematics, mathematical models aresimply tools used to help understand water re-sources and water resource management activities.Before the dams and sewage treatment plants arebuilt, before actions are taken to comply with

regulations, problems must be analyzed to deter-mine an appropriate way to proceed.

This part of water resource management, thoughnot as apparent as the reservoirs, pipes and sewers,is a vital component in meeting the Nations waterresource needs. As the desire for more and cleanerwater grows, careful analysis becomes more impor-tant. Today, wasting water reduces the amountsavailable for others. Over-building dams or sewagetreatment plants wastes money that could be avail-able for other purposes.

Sophisticated analysis, through the use of models,can improve our understanding of water resourcesand water resource activities, and help preventwasting both water and money.

This assessment of water resource models istherefore not an assessment of mathematical equa-tions or computers, but of the Nation’s ability touse models to more efficiently and effectively ana-lyze and solve water resource problems. The assess-ment considers not only the usefulness of the tech-nology-the models—but the ability of Federal andState water resource agencies to effectively use theseanalytic tools.

Models have been available to assist waterresources management, planning, and policy forseveral decades. In 1959, the former Senate SelectCommittee on National Water Resources made oneof the earliest uses of models for policy purposes.The committee investigated the importance of waterresources to the national interest, and consideredthe Federal activities required to provide the desiredquantity and quality of water. To aid in its investi-gations, the committee called on Resources for theFuture to develop a model of water supply and pro-jected use for 1980 and 2000.1

During the 1950’s and early 1960’s, many waterresource professionals began to realize the poten-

25

.

26 ● Use of Mode/s for water Resources Management, p/arming, and pO/iCY—

tial of models for improving management and plan-ning—but were overly optimistic about the easewith which these tools could be developed andadopted for general use. During the 1970’s, as com-puters became more readily available and the costof computation decreased, model developmentflourished. However, as often occurs, the technol-ogy outstripped the capability of the institutions—the State and Federal agencies—to support it.Today, model use is increasing the efficiency andlowering the cost of water resource management,but the potential for further improvement remainsgreat.

The following section of this chapter outlines thebasic principles and functions of water resourcemodels, and briefly describes the major types andclassifications of the models. A further section in-troduces the 33 major water resource issues (table1) for which model use was analyzed and surveyed.The chapter concludes with a case study that illus-trates how models were used to deal with a varietyof water resource problems in the Riverhead-Pecon-ic area of Long Island, N.Y.

Table I.—Specific Water Resource Issues Addressed in Report.-

Surface water flow and supplyHydrology:

Flood forecasting and controlDrought and low-flow river forecastingStreamflow regulation (including reservoirs)Instream flow needs (fish and wildlife, recreation, hydro-

electricity, etc.Use:

Domestic water supplyIrrigated agricultureOff stream use (other than domestic and agriculture)Water use efficiency and conservation

Surface water qualityNonpoint source pollution and land use:

Urban runoffErosion and sedimentationSalinityAgricultural runoff (other than erosion and salinity)Airborne pollutants

Water quality (other than nonpoint source and land use):Wasteload allocation (point source discharges)Thermal pollutionToxic materialsDrinking water qualityWater quality impacts on aquatic life (including eutrophi-

cation)

Ground water—quality and quantityQuantity:

Available supplies and safe yieldsConjunctive use of ground and surface waters

Quality:Accidental (and preexisting) contamination of ground

water for drinking water (including toxic substances)Agricultural pollutants to ground waterMovement of pollutants into and through ground waters

from waste disposal (landfill siting, injection, etc.)Saltwater intrusion

Economic and sociaiEconomic:

Effects of water pricing on useEconomic costs of pollution control by industrial sectorBenefit/cost analysisRegional economic development implications of water

resource policySocial and integrative:

Forecasting water useSocial impact analysisRisk/benefit analysisCompetitive water use demands (by region, by sector

and water quality objectivesUnified river basin planning and management

SOURCE: Office of Technology Assessment‘-a

INTRODUCTION TO WATER RESOURCE MODELS

What are water resource models? Briefly, theyare analytical tools used to determine the conse-quences of proposed actions or forecast the quan-tity or quality of the water in the Nation’s rivers,lakes, or ground waters. These models, which rangein sophistication from simple work with a desk cal-culator to complex computer programs, are the sci-entific community’s way of understanding and pre-

dicting the workings of a water system. Models areused to synthesize and analyze the substantialamounts of water quality, quantity, and societal in-formation needed for effective planning and man-agement, Effective models condense large amountsof data, simulate the physical and biological dynam-ics within a water body, or suggest solutions thatare most equitable to competing water users.

Ch. 2—introduction to Water Resource Models ● 2 7

A model is a ‘‘numerical representation’ of howthe real world or some part of it—a lake, a dam,or a community—works. More precisely, a modeluses numbers or symbols to represent relationshipsamong the components of these real-world systems.A river basin, for example, is composed of waterflowing in natural (and manmade) channels, andmay have dams that generate electricity and createwater impoundments. The river’s waters are oftenused by domestic, industrial, and agricultural con-sumers within the basin. The basin normally con-tains a wide variety of aquatic and related wildlife,and may attract numerous users of recreation andrecreational facilities. All of these may be consideredcomponents of a river basin system; if they can be

meaningfuhy quantified, they can be included ina mathematical representation, or model, of theriver basin.

Models deal with the interrelationships amongthe components of a system. For example, the deci-sion to store water behind a dam will increase (ormaintain) the size of a lake behind the dam, anddecrease the amount of water flowing below thedam and the amount of electricity generated at thesite. The action may increase the number of fishin the lake, attracting more fishing enthusiasts, andreduce the level of water in a marsh downstream,inducing birds and other wildlife to migrate else-where. Models are simply series of equations thatexpress such relationships in mathematical form.

Photo credit: @ Ted Spiegel, 19S2

In addition to generating hydropower, this dam helps to control streamflow on the lower reaches of the river, andassure adequate water supplies in time of drought. Achieving the multiple objectives involved in reservoir management

can be significantly improved and simplified through the use of management-related mathematical models

28 . Use of Models for Water Resources Management, Planning, and policy—

To take the illustration a step further, if a modelaccurately represents a system, it can be highly use-ful in analyzing conflicts among different objectivesfor managing that system, or ways in which man-agement objectives are complementary. For ensur-ing adequate water supplies in times of drought,reservoirs must retain as much water as possible.But to control floods, unused storage capacities ofreservoirs must be available to receive excess flows.Mathematical expressions are used to represent thequantity of flood waters that can be stored whena given amount of water is being held in reservefor water supplies.

A model is necessarily a simplification of the sys-tem it describes. It would not be possible to con-struct a model that accounted for all the minute in-teractions of a complex system—but perhaps moreimportant, it would not be useful to do so, either.A model’s value as an analytical tool lies in its abil-ity to reduce the number of factors to be consideredto a manageable size, selecting the most significantinteractions in a system, and assuming that otherfactors have negligible effects.

Models of how pollutants are transported in ariver are good examples of the need for simplify-ing assumptions. In reality, the flow of a river isthree dimensional-the river moves and pollutantsare dispersed in all directions. It is often prohibitive-ly complex to represent three-dimensional pollut-ant transport, however; most river models are de-signed to describe the transport of pollutants in onlyone direction—downstream —and ignore verticalor across-channel flow. For purposes of predictingthe concentration of pollutants at a location fardownstream, i.e., at a drinking water intake pipe,at a specific time, these influences on pollutanttransport are negligible.

To determine if model assumptions—like thosemade for pollutant transport—are valid, modelresults are tested against actual measurements. Forexample, if the model’s forecast of the time of arriv-al and the concentration of pollutants at the down-stream intake pipe is close to the concentration ac-tually measured at that time, it would appear thatit is valid to make these assumptions, at least underthese conditions. Usually, in validating a model, asthis process is called, the model is compared withactual measurements under a variety of conditions.

If a model is found to be a reasonable represen-tation of the real system, it can serve a number offunctions. First, it can be used descriptively to aidanalysts in understanding how the real systemworks. By way of illustration, when a landfill leakspollutants into ground water reserves, a model canbe used to show how far the contamination hasspread, and to estimate pollution levels in a givenarea. Since these factors can only be measured bytime-consuming drilling of test wells, the model pro-vides the quickest indication of the extent and seri-ousness of the problem. The insights gained fromthe model can then be used to determine the prob-able location of the most contaminated sites, so thatdetailed field calculations can be made in thoseareas.

Models can also be used as Predictive tools. In ariver, for instance, dissolved oxygen levels dependto a large degree on levels of bacterial activity,because as organic matter bacterially decomposes,the bacteria consume dissolved oxygen. Dissolvedoxygen concentrations also depend on the exchangeof oxygen between the river and the atmosphere,algal photosynthesis and respiration, temperature,sunlight, and many other interactions. Experimentsto determine the direct effects of pollution on dis-solved oxygen levels would require inducing manydifferent levels of pollution into the river, attempt-ing to keep all the other factors constant, and meas-uring the result. The experiment would be time-consuming, costly, and difficult to control; more-over, it may be highly undesirable to run such anexperiment in the real world. Because equationsthat represent the major factors in determining oxy-gen levels can be easily manipulated, models canpredict the direct effects of various pollution levels.These models can be used to determine what levelsof sewage treatment will be necessary for meetingwater quality standards before a sewage treatmentplant is built.

Often, however, it is not sufficient to predict theconsequences of a single event or series of actions.Preventing floods on a river system, for example,involves opening the floodgates of a dam to a par-ticular position in order to release the greatest possi-ble amount of water without flooding downstreamareas. Yet if a river system had 10 floodgates, andeach floodgate had only 10 positions, a river man-

Ch. 2—introduction to Water Resource Models 29

ager would be faced with 10 billion ( 1010) possiblechoices (or combinations) of floodgate settings tochoose from in the event of a flood. Assuming thata computer model can predict the amount of waterthat will be released by a particular combination,and the impact of the release downstream, in abouthalf a minute, evaluating all the possible floodgatesettings would require approximately 10,000 years.However, models can also be designed as optimiz-ing tools that use mathematical logic to determinethe best available choice of settings that satisfies therequirements.

The models analyzed in this report address awide range of water-related issues. These issues canbe organized into four broad categories: surfacewater flow and supply, surface water quality,ground water quality and quantity, and economicand social.

The category of surface water flow and supply in-cludes surface hydrology and water use. Hydrologyrefers to physical factors that influence the move-ment of water in rivers and streams. Use, in thiscase, means water that is withdrawn from a streamfor a specific purpose.

Surface water quality issues are divided into pointsources (e. g., discharges from a factory) and non-point sources (e. g., agricultural runoff).

The third category contains issues pertaining toground water, including available supply and qual-ity with respect to intended use. Also included inthis grouping are factors relating to the possible in-teractions between ground and surface water re-sources.

Economic, social, and interrelated factors fall intothe fourth and final category. Included are the eco-nomic and/or social factors that might influence,either directly or indirectly, the availability, quality,or demand for water resources.

In further categorizing models, it is often usefulto distinguish between two major benefits thatmodels can provide: 1) delivering information moreefficiently than was previously possible; and 2) inte-grating data to create information that would nototherwise be available. Models that perform the firstfunction rely on established methodologies (e. g.,traditional engineering formulae) but use the com-puter to speed calculation. Models that produce

otherwise unavailable information incorporatemethodologies that require computer assistance fortheir execution.

Water resources models can also be characterizedby the purpose for which they are used. These in-clude: 1) operations and management; 2) planning;3) policy development; 4) regulation; and 5) datamanagement.

Models for operations and management are used tosupport short-term managerial decisions. Thesemodels might be used to control the operation ofa sewage treatment plant or to regulate waterflowsthrough a system of reservoirs within a river basin.

Models that support Planning activities are oftenbroader in scope than operations and managementmodels, as they are used as an aid to medium-rangedecisionmaking. Planning models might be usedto evaluate alternatives for future expansion of atreatment plant or to study the impact of the pro-posed development of a water-consuming industryalong a river or stream.

Models used for long-range planning would fallunder the class of policy development models. Policymodels might be used to estimate the effects ofenergy development on western U.S. water re-sources.

Models for regulation are those used in direct sup-port of enforcement or promulgation of standardsor in the issuance of permits. For example, a regula-tion model might be used to determine the allowabledischarge level for a sewage treatment facility priorto the issuance of a permit for facility expansion.

Some models are developed solely for data manage-ment-organizing and accessing data. These modelsusually are supported by extensive monitoring andreporting networks, and may include data for awide range of water-related issues.

Yet another method to classify models is by theirtechnical characteristics. Two of the technical cate-gories most germane to this report are: 1) prescrip-tive v. descriptive models; and 2) deterministic v.probabilistic models.

Descriptive, or simulation, models “describe” howa system operates, and are used to determinechanges resulting from a specific course of action.

30 . Use of Models for Water Resources Management, Planning, and Policy

They are often used to test alternative plans untila satisfactory option is found.

Prescriptive, or optimization, models, on the otherhand, “prescribe” a course of action that best meetsa specified objective (e. g., least cost or greatestwater yield). If more than one objective is specified,these models can be used to describe the tradeoffsamong best solutions for the various objectives.

In deterministic models, the results of an event orseries of events are given as a single number or dataseries, without indication of extent of possible error

in the resulting calculations. The quantitative rela-tionships among the parts of the system are fixed—results are completely ‘‘determined’ by the modeland the data provided.

Probabilistic, or stochastic, models produce datathat are expressed as a range of probable results.Such models take into account the fact that manyevents appear to occur randomly. For example, theintensity and timing of any particular rainfall eventcannot be precisely predicted, but must be de-scribed as a probability of occurrence.

WATER RESOURCE ISSUES

A broad spectrum of activities is involved inmanaging water resources. Networks for receiving,routing, and using rainfall—both manmade facil-ities and alterations to natural systems—must beplanned, built, and operated. The quality of variouswater supplies must be analyzed, regulated, and,if necessary, improved through treatment and othermanagement practices. Supplies and qualities ofground water reserves must be determined, and re-sponsible planning provided for their continued use.Perhaps most importantly, effective and efficientstrategies must be designed for aiding users to getthe greatest possible benefit from the water theyconsume—in agriculture, residential uses, and in-dustry, as well as for recreational purposes and theprotection of natural environments.

Professionals have found modeling useful in vir-tually all aspects of these activities. Chapter 6,“Modeling and Water Resource Issues, ” presents32 of the 33 specific issue areas in water resourcemanagement listed in table 1, and details the man-ner and extent of current model use for each. Abroad and more general overview is provided be-low, to introduce the reader to the kinds of activitiesinvolved in model-aided water resource analysis andmanagement. Italicized words or phrases representissues specifically analyzed for this report, and ad-dressed in chapter 6.

Perhaps the most striking example of man’s in-teraction with the hydrologic cycle is flooding. Inaddition to the natural potential from spring rains,hurricanes, and the like, urbanization and other

land-use activities can aggravate flooding problems.In 1975 alone, 107 lives were lost and $3.4 billionin property damage resulted from flooding. At thesame time, $13 billion has been spent on flood man-agement and control since 1936.2

To a degree, man has learned to manage floods.Dams have been constructed that can store flood-waters, releasing them gradually. Stream channelshave been straightened and dredged to transportfloodwaters more efficiently. More recently, non-structural alternatives, including flood forecasting,restrictions on building in flood plains, and flood-proofing, have received attention. Models havebeen widely used to assist in both structural andnonstructural flood management, including the de-sign and operation of dams and other structuralcontrols, the delineation of flood-prone lands, andadvanced warnings of floods.

While some areas of the country are plagued withtoo much water, other regions may be troubled bya lack of it. Low rates of precipitation, bothregionally and seasonally, can result in both droughtand low stream flows. The Water Resources Coun -cil has identified 17 out of 106 water resourcesubregions that either have serious water deficien-cies at present or are projected to have them by theyear 2000.3 Figure 1 illustrates the regions projected

‘U. S Water Resources Council, 73e Nation Water Resources1975-2000, (Washington, D. C.: U.S. Government Printing Office,1978). (Hereafter: WRC, 1978).

‘Ibid.

Ch. Z—Introduction to Water Resource Models . 3 1

to experience surface water supply and related prob-lems through 2000.

Models similar to those used for flood forecastingand control can estimate the frequency, timing, andextent of droughts or low flows. This informationcan assist reservoir managers in preparing for po-tential conditions of limited water or in institutingappropriate conservation measures prior to periodsof water shortage.

Streamflow regulation is often associated withtradeoffs among competing objectives. For exam-ple, storing reservoir water for droughts may reducethe availability of water for downstream fish andwildlife habitats. Reservoirs must be operated tomeet often-conflicting multiple objectives. Modelscan help evaluate the tradeoffs among these objec-

tives, so that managers can determine an equitablestrategy for operating reservoirs.

Conflicting objectives for water are not limitedto reservoir operation; intense competition betweeninstream and offstream uses also exists. Instreamj70wneeds include adequate water for fish and wildlifehabitat, recreation, navigation, and the generationof hydroelectricity. Offjstream uses include irrigatedagriculture; domestic water supply; and water formanufacturing, minerals, and energy production.When water is withdrawn from streams in theUnited States, about two-thirds is returned; theone-third not returned is termed ‘‘consumptiveu s e . Among offstream uses, by far the greatestconsumptive user of water is agriculture. In 1975,agriculture accounted for over 80 percent of thetotal U.S. water consumption.


Figure 1 .—Inadequate Surface Water Supply and Related Problems

.

Explanation

Subregion with Inadequate streamflow (1975-2000) Inst ream use

u

*

●

xA

SOURCE:

70 percent depleted in average year ● Fish and wildlife habitat or outdoor recreation

70 percent depleted in dry year t Hydroelectric generation or navigation

Less than 70 percent depleted

Specific problems as Identified by Federa/ and State/Regkvra/ Boundaries

Study Teams — W a t e r r e s o u r c e s r e g i o n

Conflict between off stream uses “-...”.”... SubregionInadequate supply of fresh surface water to support—

OfLstream use

Central (municipal) and noncentral (rural) domestic use

Industry or energy resource development

Crop irrigation

U.S. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978.

Total withdrawal of water for offstream use is analyses, resulting in major financial and energy-expected to decline slightly by 2000 due to im- related savings, and alleviating demands on scarceprovements in water use efficiency and conservation. ground and surface water reserves. However, whileSignificant improvements in the efficiency of irriga- withdrawals are expected to decline by 2000, it istion practices have been made through model-based predicted that the annual consumption of water will

Ch. 2—Introduction to Water Resource Models . 33—— ———.—- ———. —

increase by 27 percent over the same period.4 Thisincrease in consumptive use will aggravate the con-flicts between instream and offstream water uses.

Decisionmakers at all levels of government areresponsible for balancing these competing uses; awide variety of models is available to assist the deci-sionmaker with this charge. Models can assist inallocating streamflow among conflicting users, andhelp forecast future water needs for formulating cur-rent policies, long-range planning, and manage-ment practices.

Despite the progress made over the last decade,the effects of municipal and industrial point sourcewaste discharges on water quality are still wide-spread. About 90 and 65 percent of the Nation’sriver basins are affected by municipal and industrialdischarges, respectively. 5 Figure 2 illustrates theregions of the country exposed to point-source sur-face water pollution problems. Models can estimatethe ability of streams to assimilate pollutants fromthese various point sources so as to meet receivingwater quality standards. Such wasteload allocationmodels are extensively relied on for planningpurposes.

Therma/ additions from electric power generationand manufacturing sources elevate stream tempera-tures, and can significantly affect aquatic life if thetemperature rise or rate of change is great enough.Models are routinely employed to estimate the ef-fects of thermal wastes from existing and plannedfacilities.

Dispersed nonpoint pollution sources are equallysignificant contributors of contaminants to the Na-tion’s waterways, and are significantly more diffi-cult to analyze and control than point sources.Figure 3 illustrates the areas of the country exposedto nonpoint pollution problems. An Environmen-tal Protection Agency inventory estimates thatabout one-third of the oxygen-demanding loads,two-thirds of the phosphorous, and three-quartersof the nitrogen discharged to streams comes fromnonpoint agricultural sources. Agricultural runoff, themost widespread nonpoint source problem, affects70 percent of the country’s major river basins.6

+ 1 bid11 ‘ .$ L P .4 .!’a[~ona[ JI kt~r Qua[lt) In~ ro to r ) — 1‘}77 R@Jrt to (,’on -

<~fj~, f:I’.A-44f)/4-78-f)ol“It)l(~

Runoff and irrigation return flows contribute highconcentrations of fertilizers, pesticides, herbicides,sediment, salts, and minerals. Excessive salinity, dueto the leaching of salts from the soil by irrigationwater, may affect receiving waters to the extent thatthey cannot be used for irrigation downstream.Models can be used to help farmers design ‘ ‘bestmanagement practices’ to minimize nonpointsource agricultural pollutants.

Although erosion, and the resulting sedimentationin waterways, are natural processes, human activ-ities— in particular, agriculture—have acceleratednatural rates of soil loss. Sediments from erosionclog waterways and build up in the slower reachesof streams, lakes, and reservoirs. Sediments alsocarry such pollutants as phosphates and pesticides.Models are widely used to evaluate land-use man-agement practices for minimizing soil erosion, aswell as to assess the transport and deposition of sedi-ments for river management.

Storm runoff from urban areas—containing oil andgrease, lawn fertilizer, garbage, and soil from con-struction sites— affects half of the Nations riverbasins. Models of urban runoff can be used to sim-ulate the quantity and quality of pollutants froma particular area and to compare the effectivenessof alternative control strategies.

Airborne pollution is also a source of nonpoint con-taminants. For example, the combustion of fossilfuels produces sulfur and nitrogen oxides, whichhave been linked to the phenomenon of “acidr a i n . While the ultimate effects of airbornepollutants are not certain, increased rainfall acidi-ty has led to such effects as the loss of fish in sen-sitive lakes. Models that deal with acid rain andother airborne pollution to water are currently beingdeveloped.

Water pollution from both point and nonpointsources can have harmful effects on aquatic life. Exces-sive concentrations of nutrients can cause explosivegrowth of aquatic plants. organic wastes, such assewage, can reduce oxygen levels in lakes andstreams, adversely affecting fish. Models can beused to assist biologists in determining the effectsof various pollutants on aquatic life.

Toxic pollution of drinking water is one of the mostserious water quality problems facing the Nat iontoday. The magnitude of the problem is large—


Photo cred/t: G Ted Spiegel, 1932

Fry at left have been raised with only 20 percent of the normal oxygen level of freshwater. The EPA laboratory in Duluth,Minn., performs experiments like these to determine what conditions are necessary to assure that offspring developnormally, like those on the right. Models that estimate oxygen levels in water bodies, when combined with Iaboratoty

data, can be used for estimating effects of actual conditions in rivers, lakes, and streams on aquatic life

30,000 chemicals identified as toxic to humans arepresently produced commercially. Many toxicantsare difficult to detect and remove using presenttechnologies. Extensive potential exists for usingmodels to trace the transport and fate of toxicantsthrough the environment, and to test different man-agement approaches for preventing toxicants fromreaching water supplies.

Other agents of water-borne disease also posethreats to drinking water quality, including bacteriaand viruses. Over 4,000 cases of water-related ill-nesses are reported each year, primarily from bac-terial and viral sources. 7 While surface waters areextensively treated before distribution to users,

7WRC, 1978.

ground water, which serves up to 40 percent of thepopulation, is frequently consumed untreated fromindividual wells. Toxicology models, which relateconcentrations of hazardous substances to humanhealth, are used to aid in setting standards.

Stored underground in the Nation’s groundwater reserves is an amount of water equal to 35years of surface water runoff. Nonetheless, groundwater resources are exhaustible. Aquifers—water-bearing soil or rock— can be overexploited if groundwater is removed faster than it can be recharged.Ground water ‘‘overdraft’ can result in increasedwater pumping costs, declines in streamflow, landsubsidence, and saltwater intrusion. Figure 4 il-lustrates the regions of the country experiencingsignificant ground water overdraft. Assessing avail-

Ch. Z—Introduction to Water Resource Models 35

Photo credit: C Ted Spiege/, 1982

A soil scientist examines damage to cotton crop causedby excess salinity in the San Joaquin Valley, Calif.


Figure 2.—Surface Water Pollution Problems From Point Sources (municipai and industrial waste)(as identified by Federai and State/Regionai study teams)

Explanation

Area problem

Area in which significant surface water pollution from point sourcesis occurring

Unshaded area may not be problem-free, but the problem was notconsidered major

Specific types of point source pollutants

Coliform bacteria from municipal waste or feedlot drainage

PCB (polychlorinated biphenyls), PBB (polybromated biphenyls,PVC (polyvinyl chloride), and related industrial chemicals

Heavy metals (e.g., mercury, zinc, copper, cadmium, lead)

Nutrients from municipal and industrial discharges

Heat from manufacturing and power generation

Boundaries

Water resources region

Subregion

SOURCE: US. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978.

Ch. 2—Introduction to Water Resource Models . 37

Figure 3.—Surface Water Pollution Problems From Nonpoint Sources

Explanation

Area problem

Area in which significant surface water pollution from nonpointsources is occurring

Unshaded area may not be problem-free, but the problem was notconsidered major

Specific types of nonpoint source pollutants

● Herbicides, pesticides, and other agricultural chemicals

Irrigation return flows with high concentration of dissolved solids

● Seawater intrusion

o Mine drainage

Boundaries

— W a t e r r e s o u r c e s r e g i o n

● “-.... . Subregion

SOURCE: U.S. Water Resources CounciL The Nation’s Water Resources, 197fKW00, WMume 1: Summary, December 1978

able supplies and aquifer yields from individual aqui- In some areas, however, the excessive use offers is a pressing need; models are widely used tools ground water has stopped too late. Major drops infor managing, regulating, and planning the use of ground water levels have caused the land to settleground water. Models can be used to design a well or subside, damaging buildings, roads, and rail-

field for greatest efficiency, to assess the extent of roads, and causing flooding in coastal areas. Sa/t-usable supplies, and to predict water-level declines water intrusion-penetration of underlying saltwatersresulting from alternative development schemes. into the freshwater layer—has also been caused in

38 Use of Models for Water Resources Management, Planning, and Policy

Figure 4.—Ground Water Overdraft and Reiated Probiems

1 I - 1

Explanation

SOURCE: U.S. Water Resources Council, The Nation’s Water Resources, 1975 -2(W0, Volume 1: Summary, December 1978.

coastal areas by excessive pumping. Similarly,ground water overdrafting may draw poor qualityground water near the land surface into deeper,high-quality ground water reservoirs. The likeli-hood of encountering these problems in a particularcommunity or region can be assessed with models.Models can also help to evaluate management strat-egies to minimize the risk of such occurrences.

Many ground water users are now attemptingto manage the conjunctiue use of ground and surfacewaters to assure adequate water supplies. Whenavailable, surface waters are used to meet demands,while ground water is relied on primarily duringdry periods. Ground water aquifers are often hy-drologically connected to surface lakes and streams;models can be used to analyze their interaction and


aid in their combined management, providing in-formation about both quantity and quality aspectsof ground and surface water interrelationships.

In the past, ground water was generally consid-ered to be a reliable source of high-quality water.Yet pollutants from many sources enter the groundwater system, though the extent and seriousness ofcontamination has only recently been recognized.Moreover, the ability of aquifers to rid themselvesof pollutants is limited by the slow movement ofground water.

Accidental ground water pollution frequentlywent unnoticed due to the ubiquitous nature ofcontamination—from road salt, oil and gasoline,and other chemical spills and leaks. Waste disposalhas also been a major source of ground watercontamination. Wastes are sometimes injected in-to deep wells, which, if improperly designed, cancontaminate drinking water. Toxic chemicals havefound their way into ground water from municipaland industrial landfills and dumps. Seepage fromseptic tanks has for many years been recognizedas a major source of bacterial contamination ofground water. In addition, agricultural pollution ofground water can occur from pesticides, fertilizers,and salts leached from the soil by irrigation waters.Once contamination occurs, the time and cost ofreversing the process can far exceed the cost ofpreventing it. Models can be used to estimate theinfiltration of these pollutants into ground waterand the movement of contaminated water throughan aquifer. They also have potential for aiding thedesign of waste-disposal landfills and injection wellsto minimize the potential for polluting groundwater.

Shortages of water, poor water quality, andflooding have obvious effects on society. Perhapsless obvious are the indirect economic and socialeffects that result from efforts to ensure or enhancewater supplies and quality. The construction of amultipurpose reservoir, for instance, will bring aninflux of construction workers from outside the localcommunity. A part of the salaries these workers re-ceive will be spent within the community, thus stim-ulating the local economy. An increased popula-tion, however, may also tax the local community’sability to provide adequate services such as educa-tion or police protection.

Part of the need to consider the social impacts ofmany water resource programs and projects stemsfrom the uneven distribution of benefits and dif-fering perceptions of the effects by various groups.Models can assist the decisionmaker by both orga-nizing information on the social implications of aproject and determining what social effects may oc-cur and who may be affected.

Closely associated with social impacts are theregional economic development implications of waterresource policies and projects. A new reservoirmight stimulate increased recreational activities thatsubsequently attract new businesses to an area, ormake a region more desirable for siting industriesor utilities. Models have been developed that pro-ject changes in the level of local or regional eco-nomic activities resulting from water resource pro-grams and projects.

The desirability of a project or policy may oftenbe studied using a benefit/cost analysis, which attemptsto assess relative economic efficiencies, weighingthe monetary benefits of a project against economiccosts. Models can be used both to assist in measur-ing the benefits and costs and to undertake thebenefit/cost analysis itself.

The costs to industry of pollution control can also haveeconomic implications that affect such factors as in-dustry location and national inflation levels. Modelsare used to determine the impacts of these costs oneconomic indicators like the Consumer Price In-dex and the gross national product, as well as to

determine the impact of these costs on specific in-dustries.

Since the economic and social effects of water-related development extend beyond a project’s im-mediate location, it is often important to analyzethese effects on a regional basis. Water resourcestrategies can be developed through unified river basinplanning and management, in which projected wateruse demands, water quality objectives, and numer-ous secondary considerations, including desiredlevels of economic development, are balanced andcoordinated. Models are useful in many aspects ofsuch planning.

Another analysis that is often necessary in theproject-planning process is the consideration of un-certainty. Risk/benefit analysis weighs the proba-

40 ● Use of Models for Water Resources Management, Planning, and POliCY

bility of some outcome—a flood or drought—against the benefit that would potentially be de-rived, for instance, if a reservoir were built tomitigate the impacts of these floods or droughts.Models can help evaluate both the risks and benefitsinvolved in projects to aid decisionmakers in deter-mining acceptable levels of risk.

One influence on present use of water is price;raising the cost of water can reduce demand in somesectors, especially agriculture. This economic ap-proach to conservation is particularly important be-cause it can alleviate both the need for construc-

tion of expensive, large-capacity structural supplysystems and the necessity for regulating water use.Models can determine the effects of water pricing onuse by analyzing consumer response to price.

For regional and national analyses, forecastingwater use requires an evaluation of population andeconomic growth, employment, industrial expan-sion, etc. to project future water needs. Models canestimate future levels of water use both by project-ing past economic and demographic trends and bysimulating the relationships between these factorsand water use.

CASE STUDY OF MODEL USE: WATERRESOURCES IN LONG ISLAND, N.Y.

On Long Island, N. Y., water is a critical re-source. Ground water is the sole source of drink-ing water for the island’s 3 million residents andis endangered by contaminants from leakage of sep-tic tanks, landfills, and other sources. Along LongIsland’s coast, rapid overdrafting of ground waterhas caused the intrusion of saltwater into freshwateraquifers. In addition, Long Island’s rivers, bays,and estuaries, foundations of a fishing and tourist-based economy, are threatened by domestic andindustrial wastes. In the past, contamination fromthese wastes has resulted in bans on fishing and theclosing of public beaches.

In 1970, the Nassau-Suffolk Regional PlanningBoard found that the most obvious limit to futuregrowth on Long Island was the availability of pot-able water. The board developed a ComprehensiveLand Use Plan, which recommended seeking addi-tional funds to conduct water quality studies onLong Island, and provided an impetus for morerational management of the island’s water re-sources. Soon after, section 208 of the FederalWater Pollution Control Act of 1972 became thevehicle for undertaking these further studies anddeveloping a regional strategy for treating and dis-posing of domestic and industrial waste. The

.


Nassau-Suffolk Regional Planning Commissionwas designated as the local agency responsible forcarrying out this investigation.

In designing a waste management strategy, thecommission relied heavily on models to provide aquantitative framework for making managementdecisions. a While water quality conditions were di-rectly measured whenever possible, the geographicscope of the island and the expense of drilling test

wells to analyze groundwater conditions precludedextensive direct measurement. The executive direc-tor of the Nassau-Suffolk section 208 study notedthat a wide variety of models was necessary to pro-vide information for evaluating alternative wastemanagement strategies and plans:

Long Island’s $5.2 million 208 study could nothave been completed without the application ofmanagement, physical, chemical, analogue andhydrogeological models. These models were neces-sary to help replicate a 1,200 square mile, geologic-ally complex area. g

The nature of the management decisions facingLong Island also favored the use of models. Tominimize the environmental impact of a wastewatertreatment plant, for example, it is necessary to eval-uate many alternative sites to determine its opti-mum location. The time and resources availablefor measurement limits the number of alternativesthat can be evaluated. Models can help eliminateless desirable alternatives, focusing time andresources for detailed field testing on the most feasi-ble sites.

Several options, for example, were available formanaging the wastes of the Riverhead-Peconic areaof Long Island (fig. 5). One or more regional, sub-regional, or local sewage treatment plants could beconstructed to handle domestic wastes; alternative-ly, wastes could be diverted to the existing River-head plant. One factor in the decision was the rela-tive impact of waste discharges from the varioustreatment alternatives. Several options were againavailable: dispose of the wastewater in Flander’sBay, discharge it into the Peconic River, or inject

8 The Long ~s[and Comjvehenslue i~’aste Treatment .~ana{ement plan, \’o]-ume 1 : Summary Plan; \’olume 2: Summary, Documentation ( Haup-pauge, .N, Y.: .Nassau-Suffolk Regional Planning Board, 1978),

‘Lee H Koppelman, personal commu nicat ion to OTA staff, No\,24, 198]

it or allow it to infiltrate into the aquifer. The com-mission also considered nonpoint sources of wastesand alternative means of controlling them—zoning,street cleaning, special agricultural practices, etc.

The commission had to use several models to

evaluate the various alternatives. First, to deter-mine the quantity of water and the amount of pol-lutants originating from nonpoint sources, the com-mission utilized a water budget model. For a givenquantity of precipitation, this model projects theamount of water that will infiltrate the aquifer;return to the atmosphere via evaporation or planttranspiration; or reach rivers and streams overland.Changes in land-use practices—particularly the

construction of impervious surfaces, like parkinglots, and the removal of vegetation—alter the pro-portions of ground water infiltration, evapotranspi-ration, and runoff. The water budget model canrespond to actual or hypothetical changes in landuse by estimating changes in the proportional dis-tribution of precipitation. In most cases, with in-creasing development, recharge to the aquiferdecreases, while runoff normally increases.

An increase in overland runoff tends to increasethe load of pollutants discharged—e. g., sedimentfrom construction areas, grease from urban streets,and fertilizers from agricultural land. Runoff canthus contribute a major source of contaminants towater bodies such as the Peconic River and Flan-ders Bay. The water budget model can be extendedto estimate the load of nutrients contained in ur-ban runoff and the total input of these nutrientsto the bay. Thus, as a planning tool, the waterbudget model can be used to: 1) estimate the ef-fects of altering land-use practices to reduce excessrunoff and ensure recharge of ground water;2) estimate the effects of altering land-use practicesto reduce sources of nonpoint source contaminants;and 3) determine the relative amounts of total bayand river system contamination contributed bynonpoint sources.

Other models are used to predict the impact ofwaste discharges from point sources on the PeconicRiver and Flanders Bay. These models simulatethe currents and circulation patterns of these waterbodies and project the transport and fate of pollut-ants once discharged. Different models must beused for the river and the bay because of differences

c 1– . I – c -

42 . Use of Mode/s for Water Resources Management, Planning, and Policy

Figure 5.—Riverhead-Peconic Area, Long Island, N.Y.

Calverton

r-~(n 6“ South

cm

Peconic

& Flanders Bay ,*

p econ l ~ s w a n P O n d p o n dLake

Cedar .7

%Wildvw30d Lake “charge

w

E lSTP Sewage Treatment Faclllty Alternatives d : : : : . ? . ]

~ B e l l o w SPond

SOURCE: The Long Island Comprehensive Waste Treatment Management Plan, vol. 2, figs. 7-27, 7-28.

Ch. Z—Introduction to Water Resource Models ● 4 3

in their currents and circulation patterns. Not allareas of a bay or river disperse pollutants equally;e.g., some sections of Flander’s Bay are isolatedfrom its primary circulation patterns. Since nu-trients stimulate algal growth, which can severelyaffect water quality, it is advantageous to rapidlydisperse wastewater discharges to the bay. The riverand estuary models can assist in determining anacceptable location for wastewater disposal.

The river and bay models assume that the growthof algae in these water bodies depends primarilyon the concentration of nutrients from waste dis-charge, However, other factors like ‘‘grazing’ ofthe algae by herbivorous zooplankton and recyclingof nutrients from decomposing organic matter alsoinfluence algal populations. To account for thesefactors, the commission used an ecological modelthat simulates algal growth more accurately, Theecological model more fully explores the impactsof both point and nonpoint source discharges onthe bay ecosystem.

An alternative to discharging wastewater to thebay or river is to discharge treated effluents byeither injecting them directly into the ground wateror allowing them to slowly percolate into the aqui-fer. These approaches have the potential advantageof recharging declining ground water levels; how-ever, they could also contaminate the ground water.Several different models were used to assess the im-pact of recharging ground water with wastewaterin the Riverhead-Peconic area. One model typeprojects the effect of recharge on the height of thewater table and the flow and distribution of rechargewater in the aquifer.

A second model describes the way in which pol-lutants are transported with ground water flow.This type of model is used to estimate how a leak-ing septic tank, an injection well, or a rechargebasin will affect ground water quality.

It is important to note that these models are notdesigned to make management decisions them-selves. Many qualitative and quantitative consider-ations that affect management decisions are notwithin the scope of the models’ analyses. For exam-

Photo credit: O Ted Spkge/, 1982

Construction crews prepare a wastewater injection wellon Long Island. Wastewater will be pumped directly intothe ground water table to prevent saltwater intrusion.Prior to construction, models were used to assess theinjection well’s potential to recharge (elevate) groundwater levels, as well as to assess the possibility thatwastewater could contaminate ground water supplies

pie, while a model may help to guide the selectionof an adequate location for releasing treated sewageoutflows in terms of water quality considerations,it does not consider many other factors, like a site’srecreation or habitat potential, which are necessary

aspects of the decisi~nmaking process. Models arevirtuall y indispensable, however, for their ability

to both describe and project, in a quantitativeframework, the effects of alternative managementdecisions.

Chapter 3

General Issues in ModelDevelopment, Use, and

Dissemination

Contents

PageSupport Services for Disseminating and Using Existing Models Effectively . 47Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Informing Users of Available Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50User Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Maintenance and Improvement of Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Additional Model Characteristics Affecting Ease of Model Use . . . . . . . . . . . . . . . . 52

Issues in the Development and Use of Models . . . . . . . . . . . . . . . . . . . . . . . . . . 53Interaction Between Modelers and Decisionmakers . . . . . . . . . . . . . . . . . . . . . . . . . . 53Evaluating Models for Use by Water Resource Managers . . . . . . . . . . . . . . . . . . . . 55Mechanisms for Assuring Adequate Oversight of Model Development . . . . . . . . . 59Legal Aspects of Model Use in Administrative Processes . . . . . . . . . . . . . . . . . . . . . 61

FIGURE

FigureNo. Page

6. Comparison of Measured and Computed Runoff for the Storm ofAug. 2, i963—Oakdale Avenue Catchment—EPA Stormwater Management Model 57

Chapter 3

General Issues in Model Development,Use, and Dissemination

Models are increasingly used to analyze a widevariety of resource issues because they can provideinformation that is either unavailable from othersources, more accurate than that provided by othersources, or quicker and less costly than that pro-vided by other sources. However, as with manynew information technologies, institutions have en-countered problems in integrating modeling andmodel-generated information with established oper-ating procedures, professional responsibilities, andchannels of communication.

When modeling efforts are supported by publicfunds, institutions that develop models have respon-sibilities for ensuring the availability y and usabilityof such tools for other institutions. To effectivelycarry out these responsibilities, model-sponsoringorganizations must devise strategies to informpotential users of the existence of relevant models,ensure that the model’s purpose and workings areexplained in writing so that decisionmakers candetermine its applicability to a given problem, anddisseminate the model to those who request it. Ad-ditional support services include developing pro-grams to train and assist users to operate modelsand interpret results, maintaining and improvingexisting models, and designing models for ease ofuse by other institutions.

The process of developing and using models alsorequires extensive consultation between highlytrained technical and scientific personnel on one

hand and mid- and upper-level managers on theother. Yet decisionmakers are often unprepared toinvolve themselves in the modeling process, andmay consequently be uncertain of how to use modelresults. Similarly, modelers may be equally un-prepared to build models that provide the kinds ofinformation decisionmakers need. For institutionsto make effective use of models, links must becreated among modelers, model users, and deci-sionmakers, and effective incentives be devised tomake model development and use an interactiveprocess among them. Further, institutions need todevelop procedures for evaluating the models theyuse, overseeing model development, and assessingthe legal implications and consequences of theirmodel use.

This chapter reviews the major issues associatedwith the development, use, and dissemination ofwater resource models. Many of the significantproblems associated with current model use forwater resource analysis are encountered throughoutthe modeling profession; they tend to reflect thenewness of the modeling field, and institutional un-preparedness for overseeing, supporting, and guid-ing model use.

The chapter is comprised of two major secf “ens:Support Services for Disseminating and Using Ex-isting Models Effectively; and Issues in theDevelopment and Use of Models.

SUPPORT SERVICES FOR DISSEMINATING ANDUSING EXISTING MODELS EFFECTIVELY

Once a model is operational, any potential user quate user-oriented support services, it is likely tonormally needs a great deal of information from remain unused by anyone other than its developer.the developer if he or she is to become proficient Within the modeling profession, such support serv-in running the model and interpreting its results. ices are called technology transfer and assistance. ThisA model may have been rigorously developed and section discusses those aspects of modeling that aidthoroughly evaluated, yet in the absence of ade- users in employing an existing model. Five sup-

47

48 . Use of Models for Water Resources Management, P/arming, and Policy

port activities are treated in depth; the section con-cludes with an overview of additional model charac-teristics that are linked to technology transfer ca-pabilities:

● documentation;● informing users of available models;● training;● user assistance;. maintenance and improvement of models; and. additional model characteristics affecting ease

of model use.

Documentation

Documentation is the process of setting out ex-plicit written instructions on how to use a modeland interpret its results. Although documentationis critical to the proper use and dissemination ofmodels, it is rarely carried out adequately, and isconsidered by professionals to be one of the mostneglected aspects of modeling. The lack of properdocumentation prevents potential users from dis-covering existing models that suit their needs—causing costly duplication in model development—and increases the difficulty and cost of using previ-ously developed models.

Documentation has two purposes. First, it pro-vides a nontechnical description of the basic con-cepts employed in a model, and its limitations. Sucha description must include sufficient informationto allow a decisionmaker to determine whether agiven model is suitable (and available) for a specificuse. Second, it provides technical information onthe basis of which a user/analyst can evaluate, du-plicate, and operate the model. Three kinds of doc-uments are generally used to document computermodels:

1.

2.

3.

a detailed description of the model’s purposeand assumptions;users’ manuals, which give instruction on run-ning the model—i. e., how to prepare inputto get the desired output; andprogrammers’ manuals, which explain the mod-el’s logic and internal functions, enabling theuser to adjust and adapt the model to fit hisparticular needs.

Good documentation is difficult to prepare. Mod-elers and computer programmers usually have a high-

ly developed command of technical computer lan-guages—it is in these languages that they actuallywork. Documentation requires translating the in-structions written in these languages into clearlyunderstandable English. The task is not only time-consuming— a medium-sized computer programmay consist of 4,000 sets of instructions—but it isalso one for which a technical specialist may havelittle skill or motivation. The developer of a modelhas no inherent need for documentation, other thanas a reminder of what he may forget. Documenta-tion is principally for successive users, and few in-centives currently exist for the developer to take userneeds into account in the process of model develop-ment,

Consequently, for most models, documentationeither does not exist, or exists in inadequate form,lacking in detail, and failing to serve users’ needs. 1

Model documentation is typically so brief or poorlywritten that the user is forced to resort to a trial-and-error approach to learn proper use of the mod-el, or to seek personal assistance from those whodeveloped the model.

Documentation is the primary mechanism for in-formed communication among those involved inmodeling efforts—developers, users, analysts, anddecisionmakers. Without it, the purpose, premises,and capabilities of the model remain obscure, andit becomes impossible to: 1) decide whether a modelapplies to a given problem, 2) operate the modelindependently of the developer, and 3) adequatelyinterpret and use model results. 2 Further, compe-tent documentation is important in facilitating mod-el evaluation by third parties, and in encouragingcontinued maintenance and updating to keep mod-els current.

Few institutions encourage proper documenta-tion. Seldom are funds specifically provided for thedocumentation phase of model development. Evenwhen funds are provided, if the funding organiza-tion lacks a unit that critically evaluates documen-tation in the context of using the model, developers

‘S. Gass, Computer .ilodel Documentation A Retleu and An Approach,NBS Special Publication 500-39, National Bureau of Standards, 1979.

‘G. Fromm, W. L. Hamilton, and E. E. Hamilton, Federa[~ Sup-p o r t e d ,Vlathematzca[ .h!ode[s Surue) a n d AnalYsz~, Gp(l stock#038 -000-00221-0 (Washington D. C.: Gmernmcnt Printing Office,1975), p. 44,

Ch. 3—General Issues in Model Development, Use, and Dissemination ● 49

may have little incentive to spend time and efforton the quality of their documentation work. In mostmodeling efforts, documentation is done ‘‘after thef a c t , as part of the cleanup operation at the endof the project, necessitating searches through oldrecords at a point when both time and money arein short supply.

Moreover, modelers and programmers have littleprofessional incentive to produce high-qualitydocumentation work. Documentation is a long andtedious process. Most developers see it as noncre-ative, in that it calls not for analytical or technicalskills, but rather for communicative abilities thatthe modeler frequently lacks. At present, documen-tation is also seen as contributing little or nothingto the modeler’s standing in his field.

If documentation is to be upgraded, it must be-come an integral part of model development. Themost efficient mode of creating written documenta-tion is to do so concurrently with the developmentof the model—this helps to ensure that the writteninstructions accurately reflect the actual computerprogram.

Informing Users of Available Models

Although numerous models are available to assistwater resources managers, these models are difficultfor users to identify, locate, and obtain. OTA foundthat many potential model users, and even modelersthemselves, considered the need for effective com-munication about existing models more importantthan the need for developing new models. Fre-quently, the difficulty of identifying and locatinga suitable model causes the decisionmaker to eitherforego model use for water management decisions,or leads to the development of a new model. De-veloping new models is extremely costly and time-consuming, while existing models that have beenevaluated may need only minor adjustments and‘ ‘fine tuning’ to be applied to the user’s problem.

Presently, most information on existing modelsis available only in technical journals. These tech-nical publications are geared primarily to use byscientists and modelers. Few journals aim to com-municate with decisionmakers and managers, andtheir distribution is often limited to a handful ofsubscribers. Most take over a year to publish a sub-

mitted manuscript, causing significant delays incommunicating the availability of a model.

Three ways to make information on existingmodels available to potential users were suggestedat the OTA workshops: 1 ) catalogs, 2) newsletters,and 3) model clearinghouses.

Catalogs

Various Government agencies and research orga-nizations have published catalogs of available mod-els. Such attempts to distribute model informationhave had mixed success. In the rapidly advancingfield of modeling, many catalogs quickly becomeoutdated, since new models are regularly intro-duced and old models must continually be updatedto remain current. Consequently, the maintenanceand updating of a usable catalog must be performedon a continuing basis by a staff with relatively highlevels of expertise.

A number of Federal organizations have includedmodel-related information in catalogs dealing withwater resources—most importantly, the SelectedWater Resources Abstracts and the Water ResourcesResearch in Progress File Catalog of the WaterResources Scientific Information Center. and var-ious publications of the National Technical Infor-mation Service. However, these services are notdesigned to rapidly access modeling information,and are too far removed from developers to be ex-tensively used or adequately maintained.

In addition, the Federal Software Exchange Cen-ter (FSEC) publishes catalogs of computer pro-grams that Federal agencies consider to be usableby other Federal, State, and local government agen-cies. However, the catalogs are not intended to pro-vide comprehensive coverage of even federally de-veloped models, and provide relatively scanty infor-mation regarding the models that have been in-cluded, Moreover, FSEC regulations prohibit dis-closure of the identity of the developing agency

without its prior consent, frequently precluding fur-ther inquiries by and assistance to potential users.

An extensive discussion of the functions of theseorganizations that relate to modeling is providedin chapter 4 of this report.

50 . Use of Models for Water Resources Management, Planning, and policy

Newsletters

Newsletters are a useful vehicle for disseminatinginformation about available models. An organiza-tion can publish newsletters relatively inexpensivelyas a service to current and potential users of itsmodels. Newsletter services for the Environmen-tal Protection Agency’s (EPA) Stormwater Man-agement Model (SWMM) Users’s Group and theEPA Center for Water Quality Modeling are de-scribed in chapter 4 of this report.

Model Clearinghouses

Clearinghouses offer a comprehensive approachfor disseminating information about modelsavailable from a broad range of participating agen-cies and organizations. Model clearinghouses serveas a central resource for obtaining informationabout available models, and help to address suchmodeling problems as duplication of model develop-ment efforts, and improper selection of models.

A clearinghouse’s primary function is to collectmodels and model-related information, and dissem-inate these models and information to the user com-munity. The majority of persons contacted for thisstudy indicated a strong need for a model clearing-house. One established clearinghouse for groundwater models at the Holcomb Research Instituteis discussed in chapter 4 of this report.

Of those surveyed by OTA, most who favoredthe model clearinghouse concept felt that the clear-inghouse’s primary or central role should be to in-ventory existing models. This inventory might con-sist of a central catalog of models by subject area,a list of available models, a list of agencies that usemodels, and a notation of a contact person or agen-cy for further information about each model. ForFederal agencies, an inventory would help avoidduplication of existing models and could improveinteragency coordination of modeling efforts. ForState agencies, an inventory would serve as a sourceof information on available state-of-the-art model-ing tools.

To meet model users’ needs, the clearinghousecould also establish a catalog of model characteris-tics to help users compare the advantages and disad-vantages of different models. Users seeking infor-mat ion on a particular model, or on models for a

specific problem, would submit information on thenature of the pertinent water resource problem andon any other requirements that influence the choiceof a model—such as cost, level of complexity, as-sumptions of the model, etc. In turn, trained clear-inghouse staff could quickly locate models that gen-erally fulfill these requirements.

Clearinghouses can provide assistance in otherareas as well. State survey respondents indicateda need for information on sources of technical assist-ance, training, and data, as well as information onexisting models. Some respondents suggested thatclearinghouses serve as technical assistance andtraining centers. Clearinghouses could also haveevaluative functions—developing standards for as-sessing the materials submitted, and providing tech-nical help in evaluating the utility of availablechoices.

It is unlikely that a clearinghouse could initiallybe self-financing. Seed money would invariably beneeded to get it started, and outside funding mightbe needed throughout its existence. Clearinghousescould be partially funded by private business orFederal agencies, and earn the remaining necessaryoperating funds by charging for their services.Another option is for the clearinghouse to conductand charge tuition for training courses, which wouldpublicize the organization as well as generateincome.

Training

User training is among the most effective meansfor improving the use of water resource models.Both model developers and model users who werecontacted during the OTA study consider trainingan important aspect of model support. At the pres-ent time, neither governmental water resourceagencies nor the private sector are providing thenecessary training for applying models to the deci-sionmaking process. In response to an OTA survey,State-level water resource professionals ranked fed-erally sponsored training a priority second only todata needs, and indicated a need for training assist-ance in all phases of modeling activities.

Several mechanisms can be employed for train-ing model users and decisionmakers. Individualssurveyed for this study generally agreed that one-

Ch. 3—Genera/ Issues in Model Development, User and Disssemjnatjon . 51

Photo credit: Ted Spiege/, 1982

A senior hydrologist at USGS headquarters in Reston, Va., demonstrates steps in modeiing river currents. A tapefrom the underwater monitoring equipment pictured in left foreground provides data as input to the model, which

is run on the computer terminal above. A portion of the model converts numerical informationinto charts and maps of current patterns in the river itself.

to-one interaction between developer and user isthe most successful training approach; however, itwas also identified as the most expensive trainingmethod. Hands-on workshops, which allow usersto run models on computers under supervision,were identified as the next best method. Traditionalseminar approaches were the third choice for usertraining.

A number of Federal agencies conduct user train-ing programs. The U.S. Geological Survey con-ducts numerous courses in many aspects of mod-eling, while the Army Corps of Engineers’ Hydro-logic Engineering Center (HEC) provides exten-sive training courses in the use of its major models.The Instream Flow Group (IFG) at the Departmentof the Interior specializes in training both managersand technicians in instream flow analysis, problemsolving, and related model use. Federal training ef-forts are described in detail in chapter 4 of this

report. Some agencies are using videotapes of train-ing sessions as less expensive teaching tools. otherinnovative techniques may be applicable to train-- .ing model users, including programedand self-instruction methods.

User Assistance

Documentation, training, and other

teaching aids

user aids cango a long way in preparing the decisionmaker forusing water resource models. However, direct as-sistance by experienced modelers and computerprogrammers will often be needed. Sometimes theproblem can be solved simply by a phone call; atother times, direct contact with a modeler or pro-gramer who is familiar with the model may be

needed.

User assistance may range from merely pro-viding information on the status of a new model,

52 . Use of Models for Water Resources Management, Planning, and policy— . — . — ——— ——— ————. ———————— -— - — — —

to advising on model application or preparing in-put data and analyzing results. User assistance alsohelps the modeler to better understand the problemsof applying models by interacting with the deci-sionmaker-user. Complex models may even require‘‘tutored application ‘‘ in which modeling specialistsand users work together in applying the model tothe user’s problem. Federal agency user supportgroups that have devised procedures for assistingusers include the SWMM User’s Group, HEC,and IFG. Their experiences in this area are de-scribed in chapter 4 of this report.

Maintenance and Improvementof Models

The development and improvement of modelsseldom stops at evaluation and fine-tuning for real-world applications. Models are constantly modifiedand improved based on users’ experience, new in-formation, or new methodologies and techniques.Each change in a model must be documented, andthe users notified of the modification and ad-justments in operating procedures that it requires.

It is important that the institutions that sponsorand support model development make provisionsfor updating and maintaining models after theybecome operational. Unfortunately, history hasshown that few institutions, whether Governmentagencies or academic institutions, provide for thecontingencies of model updating and maintenance.Clearinghouses or central repositories can play animportant role in ensuring that models are updatedand improved. OTA workshop participants sug-gested assigning ‘ ‘lead agency’ responsibility to aFederal Government entity for systematically track-ing Government-wide model development and up-keep.

Modeling support groups such as HEC are effec-tive means for assessing model deficiencies, main-taining and improving a model, and notifying usersof subsequent changes in a model.

Additional Model CharacteristicsAffecting Ease of Model Use

In addition to the technical assessment of a mod-el’s capabilities and the qualitative evaluation ofits credibility through operational testing (described

in the following section, Issues in the Development andUse of Models), there are other factors that affect thevalue of models as aids to decisionmakers. Theseincude:

1.

2.

3.

computational efficiency-is the model Cost

effective in terms of computer use;ease of use—is the model understandable andeasily operable by users; andtransportability-is the model designed for useon a range of different computers?

Computational Efficiency

Computational efficiency pertains to computercosts associated with operating a model. It is gener-ally achieved by carefully designing the model tomake the best use of the capabilities of a particularcomputer and by applying state-of-the-art proce-dures for manipulating and solving equations with-in the model itself.

Ease of Use

The ease with which a model can be used de-pends on the design of its input and output char-acteristics. The input characteristics of a good‘ ‘user-oriented’ model, i.e. , a model that is de-signed for use by persons other than the modeler,ensures that information and data needed for run-ning the model can be introduced into the modelwith the least effort and with minimum chances forerrors. Such a model checks the data for com-pleteness and reasonableness, and transforms it intousable form for processing. The output of a gooduser-oriented model can be adjusted to provide thelevel of detail and organization of information thatbest suits the user. If a computer run cannot becompleted due to errors or incompatibility of data,an effective model will provide an analysis of theproblem encountered (diagnostic information), andwill warn when computer-generated informationexceeds predetermined bounds.

Transportabilit y

Model transportability is the ease with whichmodels can be transferred from one computer sys-tem to another. Characteristics of computer systemsvary substantially among manufacturers. A modeldesigned to take full advantage of the various fea-tures of a particular computer system, e.g., for stor-

Ch. 3—General Issues in Model Development, Use, and Dissemination ● 53— — . -

ing information or solving equations, may needmajor revisions for use on another computer sys-tem. Costs associated with restructuring andretesting models can be substantial. If a model isintended for use on a number of different computersystems, the modeler must avoid using system-dependent features of any particular computersystem. However, designing a transportable model

often results in sacrifices of computational efficiencyand ease of use.

Designing for transportability requires knowl-edge of the characteristics of a variety of computersystems. Such knowledge is difficult to acquire andis not widespread among model developers, sinceit must be gained through operating experience ona range of computer systems.

ISSUES IN THE DEVELOPMENT AND USE OF MODELS

The model development process begins when adecisionmaker, scientist, or manager identifies aninformation need that can best be met through someform of mathematical analysis. A team of profes-sionals subsequently analyzes the issue and gathersdata on it, develops the mathematical equations thatcomprise the model, fine-tunes the model to specif-ic conditions, evaluates model results, and presentsthe model-generated information to the individualrequesting it. Oversight from the supporting orga-nization must be provided to assure that modeldevelopment proceeds effectively, and that modelresults are appropriately used. This section assessesfour major aspects of the process of developing andusing mathematical models:

●

●

●

●

interaction between modelers and decision-makers;evaluating models for use by water resourcemanagers;mechanisms for assuring adequate oversightof model development; andlegal aspects of model use in administrativeprocesses.

Interaction Between Modelersand Decision makers

The goal of the modeling process is normally toprovide results that are usable in decisionmakingprocesses—including day-to-day operations andmanagement, medium- and long-range planning,regulator y purposes, and policymaking. To effec-tively aid decisionmaking, models must provide in-formation that is relevant to the decision alternativesat hand. In addition, model results must be consid-ered reliable by those responsible for making deci-sions.

Because modeling is a relatively new field, fewdecisionmakers have had an opportunity to usemodels as part of their formal education, or to par-ticipate in model development processes. While thistrend is changing as a new generation of water re-source managers assumes positions of responsibil-ity, lack of familiarity with models and modelingconcepts remains a key impediment to increasedreliance on model-based information. Individualscontacted or surveyed by OTA repeatedly statedthat models are not used in many water resourceareas because ‘ ‘they are not trusted’ by thoseresponsible for management and decisionmaking.Conversely, models tend to enjoy high levels ofcredibility among users and decisionmakers whoare familiar with modeling techniques and with theresults of specific models.

Managers who are inexperienced in the use ofthese techniques tend to base their judgments aboutthe value of models on the experience of others. Dr.William Johnson of HEC observed that ‘ ‘the cll-terion of trustworthiness is determined by an ac-ceptable record of use (preferably by those otherthan the model developer). Results of OTAsurveys and workshops on modeling* suggest thatthe use of models in water resources managementcan be broadened by a concerted effort to familiar-ize resource managers and decisionmakers with thedevelopment and operation of mathematical mod-els.


When a decisionmaker initiates a model develop-ment effort, the value of the information he ulti-mately receives depends directly on his ability tospecify what he needs to know. Yet many profes-sionals routinely state their information objectivesin qualitative terms, and their conception of theproblem to be solved may not lend itself to quantifi-cation. Decisionmakers may also look to the modelto explain the issue, when in fact a clear specifica-tion of the issue is a prerequisite to developing mod-els of it.

A modeler who is confronted with an impreciserequest for information will normally attempt toprovide the kind of results that he or she considerscritical to the decision—often without success. Mod-elers usually have a technical or scientific back-ground that is significantly different from that ofthe decisionmaker, although there are some excep-tions. Without inputs from decisionmakers, model-ers may tend to concentrate on ‘ ‘technically cor-rect’ solutions without regard to political considera-tions that may affect the outcome of a decision.

Photo credts: @ Ted Spiegel, 19S2

Evidence that PCB levels in the Hudson River had the potential to interfere with commercial shad fishing led the NewYork State Hudson River Valley Commission to develop models to analyze the problem


Modelers may also have professional motivationsthat lead them to concentrate on developing model-ing techniques and mathematical sophistications forthe primary purpose of advancing the state of themodeling art. Rewards are frequently given on thebasis of professional contribution to the field ofmodeling rather than for developing models thathave utility for the decisionmakers. A 1975 surveyof model development project directors conductedby Fromm, Hamilton, and Hamilton,3 found thatthe two most frequently identified benefits of model-ing were: 1) ‘ ‘educated the model builders’ (78 per-cent); and 2) ‘‘pointed a way for further research’(76 percent). ‘‘ Helped in making policy choices’ranked only fifth (58 percent). The modeler’s preoc-cupation with advancing the state of the art ofmodeling, while highly useful for anticipating futureneeds and identifying critical emerging issues, oftenleads in the short run to overly complicated modelsthat require more information and data for theiruse than is practically available to the user/decision-maker.

Finally, unless the modeler thoroughly instructsthe decisionmaker on how to interpret model re-sults, the information provided may inadvertentlybe misleading. By constructing the model, a mod-eler normally gains an appreciation of its capabil-ities and limitations—in particular the range oferror associated with various model results. If thedecisionmaker is merely presented with a set of fig-ures and projections, he or she may tend to overrelyon the model accuracy or misinterpret the mean-ing of the information produced. Such overreliancemay result in a misdirected decision, and cause thedecisionmaker to avoid the use of models in thefuture.

The most effective way to avoid these pitfalls inmodel development and use is to ensure that mod-elers and decisionmakers interact and communicatewith each other throughout the model developmentprocess. The institutional setting should encouragemultidisciplinary approaches to problem solving,involving scientists, modelers, model users, andmanager-decisionmakers. The success of the model-ing effort will often depend on stimulating andmaintaining communications among these groups.

3Fromm, Hamilton, and Hamilton, op. cit., p 66

The modeler-decisionmaker team needs to en-sure that four questions are continually addressedduring model development or use:

●

●

●

●

Are we developing or using the model toanswer the proper questions?Is the model capable of producing sufficient-ly accurate answers?Will the model be an improvement over exist-ing techniques?Will the improvement in results justify modelcosts?

Neither model developers nor decisionmakerscan answer these questions in isolation from eachother. But bringing the expertise of each group tobear jointly on model development and use is initself a complex undertaking. Creating appropriateincentive structures in institutions where modelingactivities take place can have a major influence onhow well the interested parties work together to pro-duce appropriately designed models. The profes-sional climate established by top policymakers playsan important role in encouraging the use of models,training decisionmakers to use models effectively,and stimulating the development of usable model-ing tools.

Evaluating Models for Useby Water Resource Managers

Once developed, models must be evaluated toensure that the information they generate adequate-ly covers the range of conditions that the decisionobjectives demand. This requires not only an assess-ment of the technical capabilities and limitationsof the model, but also qualitative judgments con-cerning the nature and extent of the informationneeded for the decision at hand.

The evaluation process aims to answer threequestions concerning the model:

● How well does the model’s structure corre-spond to the structure of events in the realworld? Since models are simplified mathematic-al representations of real, complex relation-ships, we need to know how adequately suchsimplifications reflect the essentials of thesereal-world relationships. Are the model’s as-sumptions about real-world behavior reason-able? Does the model take account of the fac-


tors that actually characterize and control thereal-world phenomenon? Is the model sensitiveto changes in those factors that could affect thereal-world response?How accurately does the model predict eventsin the real world? What is the degree of possi-ble error gaged by some measure of perform-ance?Does the model provide the degree of accuracyand flexibility required by the user? Is infor-mation provided at an appropriate level of de-tail?

The first question is conceptually the most diffi-cult, and requires both technical and qualitativeanalysis of any given model. The second is quantifi-

+h

‘i -*46P%

Photo credit: @ Ted Spiegel, 1!?s2

Researchers take ice core samples to measure PCBdeposits at Thompson Island Dam, Ft. Edwards, N.Y.Often, data-gathering must be closely coordinated withmodeling activities if models are to provide informationrelevant to the problem at hand. Models can also be usedto help pinpoint those aspects of the problem for which

additional data collection is required

able and can be addressed by a procedure called‘ ‘validation. The third addresses the relevance ofthe information provided, and involves subjectiveanalysis of the nature of the problem being stud-ied. Modelers and decisionmakers must understandthe outcomes of all three kinds of questions if theyare to evaluate the models they use and the infor-mation that models provide them. The followingdiscussion outlines the major techniques used toprovide these answers.

Technical Assessment of Models

Three technical procedures collectively determinethe accuracy of a mathematical model: 1) verifica-tion—assuring that the computer program actual-ly performs as designed; 2) calibration-developingvalues for the constants and coefficients in the com-puter program from field data, in order to accurate-ly predict real-world events; and 3) validation-as-sessing the model’s accuracy in predicting real-world events.

Verification. —A model is said to be verified whenit is determined that the designer’s conception ofthe model is accurately embodied in the programwritten and run on the computer. Such a procedureis applicable to any model, and involves technicalchecks to ensure that:

● the written program accurately describesmodel’s design;

● the program is accurately mechanized oncomputer; and

the

the

● the mechanized program runs as expected.

Verification of a computer model may requireconsiderable effort to ‘‘debug’ (adjust the programso that it runs properly), particularly if the modelis large and complex. Although the process of verifi-cation is straightforward, and to a large extentmechanical, the expense and time delays to debuga program can be significant.

Calibration. —Models must be “fitted’ or ‘‘fine-tuned’ to the specific characteristics of the real-world system being studied. Each model containsa set of parameters, i.e., values of coefficients,that establish the relationship between the model’spredictions and the information supplied to thecomputer for analysis. A model is considered to becalibrated when model results match experimen-


tal observations taken from the particular systemunder investigation. Calibration is, thus, the proce-dure used to determine a specific mathematical val-ue for the parameters of a model.

Calibration depends on a reliable set of data col-lected under conditions as similar as practical tothose prevailing at the time of the decision. Often,however, data are not available, and the modelermust depend on assumed values or average valuesobserved previously for estimates of the parameters.The use of assumed or hypothetical values oftenreduces the reliability of the model.

Validation. —Validation is the process of deter-mining how accurately the model can predict real-world events under conditions different from thoseon which the model is developed and calibrated.To validate a model, a different set of field datais used as input to the model and the output is com-pared to actual observations of the new field con-ditions. Where possible, validation uses a complete-

ly new set of data, gathered at a different time orplace than those data used to develop and calibratethe model. However, in instances of limited data,a single data set may be split, and the two halvesbe used for calibration and validation respectively.

The simplest validation measure is a graphiccomparison of observed data and computed values.It allows the analyst to make qualitative judgmentsabout the adequacy of the model and its suitabil-ity for additional use, and provides a clearly visi-ble, easily understood assessment of model results.An example of simple graphic comparison is pres-ent in figure 6. More complex models may requirestatistical indicators of accuracy to supplement orsupplant graphic presentation. Simple statisticalmeasures comparing observed and computed valuesinclude correlation coefficients, computation ofrelative error, and comparison of means.

Validation depends on a reliable standard forcomparison. The lack of comparative data often

Figure 6.–Comparison of Measured and Computed Runoff for the storm of Aug. 2, 1963–Oakdale Avenue Catchment—EPA Stormwater Management Model

The graph above compares measured runoff to SWMM estimates of runoff for a single storm event at an individual stormwatercatchment. Amounts of precipitation falling during the course of the storm are shown at the top, and are calculated by the scaleat the right; actual and estimated discharge to the catchment is shown by the lower lines, and is measured by the scale at the left.SOURCE EPA Stormwater Management Model,


precludes adequate validation. If a model describesa unique system or event, then comparisons withdata from other systems (or times) may be impossi-ble. Some models, e.g., models of physical processeswhich are governed by law of physics and engineer-ing, are often adaptable for a wide range of applica-tions. Such models can be validated from time-series observations at a single location—comparingresults with prior historical data—or in combina-tion with similar data from other locations.

Social and economic behavioral models, how-ever, are difficult to validate in the strict sense.Human behavior cannot be analyzed in the samesense as interactions that take place in the physicalsciences. Human interactions may be extremelycomplex, and involve many factors not readily sub-ject to quantification. At best, social scientists canestimate statistical variations in human behaviorsunder a set of assumed conditions— yet there is noway to gage the likelihood that the assumed condi-tions will come to pass. This difficulty is com-pounded by the necessity to forecast changes in anumber of highly uncertain economic and socialvariables, e.g., inflation, commodity prices, anddemographic and employment patterns. Moreover,the complex interactions of the economic and socialsystems are dynamic, i.e., the nature of the systemitself continues to change, thus requiring constantchanges in the model. Under circumstances ofchanging system structure, it is nearly impossibleto use long-term time-series data for validatingmodels.

Qualitative Assessment of Models

Socioeconomic and integrated models are usedby decisionmakers to predict the likely economicand social effects of policy decisions. As explainedabove, such models cannot be validated in the tech-nical sense because there are no statistical meansfor assessing the accuracy of the model’s predic-tions until the predictions have come to pass—orfailed to do so. Moreover, the presence of factorsthat have influenced the outcome but have not beenincluded in the model may preclude any statisticalcheck on the model’s accuracy. One must thereforerely on qualitative indicators of the model’s cred-ibility and reasonableness to assess its usefulnessand reliability. Properly understood, such proce-dures permit policymakers to determine whether

a model’s predictions are sufficiently reliable toserve as an input to decision processes.

Three techniques can be used to assess complexpredictive models in a qualitative or semiquan-titative manner: 1) parts of a complex model cansometimes be validated independently of the re-mainder of the model, using historical data to testthe accuracy of the projections; 2) professional con-sensus can be obtained among experts who reviewthe reasonableness of the model’s parameters andstructure; and 3) users can perform sensitivity anal-yses, i.e., comparing the changes in model outputthat result when the model is run successively withsmall changes in model assumptions. Sensitivityanalysis places less emphasis on the absolute accu-racy of projections, and more on the differences thatresult from incremental changes in policy, for ex-ample.

The decisionmaker must be a major participantin the qualitative assessment of a model. In the ab-sence of statistical and objective measures of per-formance, one must rely on the intuition and expe-rience of the decisionmaker in judging the qualityof the information the model supplies and in weigh-ing that against the informational needs for deci-sionmaking. Similarly, the user/decisionmakermust be the final arbiter in evaluating the sensitivityof the model to changing inputs and conditions.

Assessing the Relevance of the Model

A major reason for expending the time, effort,and funds necessary for using a model is to pro-vide information that is not available from othersources. A model’s utility to the decision processdepends both on its ability to analyze informationand on the relevance of the information to the deci-sions to be made. Thus, in the find analysis, thedecisionmaker must gage the usefulness of the mod-el against the profile of the decision itself.

In some instances, a model’s primary use maybe to identify further information that may beneeded to approach the decision; thus the evalua-tion of the model proceeds as an integral part ofthe issue analysis. The term forum analysis issometimes used to indicate a procedure in whicha number of models are analyzed to determine theirrelevance to a given issue. The forum analysis be-gins as a comparative exercise, in which different



Decisionmakers must understand the assumptionsunderlying model-generated information to use it in

deciding policy questions

models are run with the same data set in order todetermine the fundamental differences in their pro-cedures and results. The information generated isthen used as a focal point for examining the issueitself, as participants attempt to specify the factorsthat influence the situation in the real world, andto improve the model’s capacities to reflect thosefactors. The “forum’ for carrying out this assess-ment simultaneously involves modelers, model ana-lysts, and policymakers. Forum analysis can be apowerful tool to advance the state of the art of mod-eling for a specific problem area, and can also con-tribute to a better understanding of the problemby providing an analytical framework for consider-ing the issues.

A recent World Meteorological Organizationforum analysis project compared 10 hydrological

models that provide short-term forecasts ofstreamflow. 4 The project used data sets from sixrivers with different physical and climatologicalcharacteristics to determine the models’ relative ad-vantages and disadvantages for assessing stream-flows in a variety of river types, and under differ-ing institutional constraints and accuracy require-ments. The exercise allowed participants in a tech-nical conference to compare the performance of thetested models, and to develop guidelines for modelselection based on such criteria as the purpose ofthe forecast, the prevailing climate within the riverbasin, and the quality and type of data and com-puters available.

Mechanisms for Assuring AdequateOversight of Model Development

Although there is broad agreement among themodeling community that additional measuresare needed to standardize and improve the qualityof models, there is significant disagreement amongmodelers as to how this should be achieved. Amongthe means of ensuring quality control of models are:guidelines, standards, contractual agreements, andpeer review. Each of these could potentially limitthe individual modeler’s flexibility and freedom toapproach problems, hence any proposal to createstandards and impose uniformity is a contentiousIssue.

Guidelines and Standards

Proponents of establishing Government-wideguidelines for model evaluation consider guidelinesan effective means of standardizing and ensuringcompatibility among model development efforts,as well as a way to screen bad models while enhanc-ing the acceptance of good ones. Such guidelinescould promote uniformity in evaluation criteria,and contribute to achieving compatibility amongmodel results.

Opponents point out, however, that the wide va-riety of user needs may preclude the use of uniformguidelines. Since a model needs primarily to match

4“Intercomparison of Conceptual Models Used in Operational Hy-drological Forecasting, “ World Meteorological Organization, WMONo. 429, Geneva, Switzerland, 1975.


the informational needs of an individual user, theuser is in the best position to determine appropriatestandards. Guidelines written to deal with a rangeof models would likely be either too vague to bepotentially useful, or limited in applicability to afew specific models. In either case, guidelines couldinhibit innovative modeling efforts which departfrom accepted practice. This could inhibit advancesin the state of the art in modeling research.

A further difficulty arises in the use of guidelineswithin an organizational framework. Procedures in-tended as general suggestions to guide modeldevelopment and use may tend in practice to beused as standards governing modeling activities. Amanager’s natural desire to minimize risk and pre-clude responsibility for failure could place pressureon users and developers alike to follow accepted,conventional procedures. In the rapidly advancingfield of modeling, such a bias could conflict stronglywith the objective of incorporating the best availableknowledge into current modeling activities.

A General Accounting Office (GAO) report5 sup-ports the guideline concept, while acknowledgingthat variations in model development efforts re-quire that guidelines be highly flexible. GAO’ssurvey of model developers in the NorthwesternUnited States revealed skepticism about guide-lines—both in general, and in reference to specificGAO proposals:

A primary concern was the fear that the guid-ance factors could become requirements for allmodeling efforts. Respondents noted that modeldevelopment efforts are not all the same. They dif-fer in size, complexity, and level of the technologybeing applied. In addition, the contractual processas well as the contractual management relation-ship will vary from project to project. Respondentspointed to these structural and management dif-ferences as evidence of the need for flexibility inimplementing any set of guidance factors. Morespecifically they noted the need to allow the man-ager freedom in determining which factors to con-sider and the level of activity required.

Survey responses prompted GAO to qualify itsproposals for modeling guidelines:

The guidance factors are not intended as abso-lute requirements. Rather, they represent a pre-liminary listing of procedures a manager shouldconsider when undertaking a model developmenteffort. These techniques are meant to provide themanager with an awareness of the total develop-ment process—not necessarily to establish a check-list for compliance. Most of the people we talkedto stated that such guidance would be useful if itremained flexible.

Standards developed for use by a single organiza-tion are less likely to encounter objections. For ex-ample, the Corps of Engineers has establishedguidelines for models that are incorporated in theCorps’ Engineering Computer Programs Library. b

The stated objectives of the guidelines are to assurethat models distributed through the library are:1) immediately usable, broad in scope, easy tomodify; 2) consistent with accepted engineeringprinciples and practices; 3) uniformly and welldocumented; and 4) readily understandable byothers and easy to set up and apply.

The standards specify the programing languageto be used, and suggest specific programing prac-tices that will enhance program usability. Detailedguidelines are provided for preparation of modeldocumentation. Models that are incorporated in thelibrary are placed in one of three categories, de-pending on the nature of the model and the levelof review it has received. For example, a model inthe highest category will have been designed forCorps-wide application, and will have received in-dependent review and approval by the Corps’ Of-fice of the Chief of Engineers. A further discussionof Corps’ procedures for developing and dissemi-nating water resource models is included in thedescription of HEC in chapter 4.

Contractual Mechanisms

Numerous proposals have emerged for strength-ening quality control by requiring the performanceof certain procedures or the attainment of perform-ance standards as part of the legal contract for devel-oping a model. For example, developers might be

5 Wa} ! to Improw ,Management OJ b’edera[~ h’unded Computerized Model~,LT s (;{)vernnlc.nt A(c ounting {)ffi( (,, 1.C;L)-75- 111, 1976.

6B. Eichert, ‘ ‘Experiences of the Hydrologic Engineering Centerin Maintaining Widely Used Hydrologic and Water Resource Com-puter Models, Technical Paper No. 56, Hydrologic Engineering Cen-ter, 1978.

Ch. 3—General Issues in Model Development, Use, and Dissemination ● 61— . — —

required to provide specific levels of documenta-tion acceptable to a review panel, or to achieve aspecific level of accuracy before final payment ontheir contracts.

Another GAO proposal called for Federal agen-cy review of contractor performance at the end ofeach of five phases in developing models. Both theagency and the developer would have an opportu-nity to terminate the development process at theend of each phase:

A contract with a breakpoint at the end of eachphase should be used so that a developer cannotproceed from one phase to the next without writ-ten approval from the user. Each phase or break-point should be separately priced so that a termina-tion at the end of a specific phase will limit theGovernment’s liability under the contract to thosecosts incurred for the contractor’s performance upto the breakpoint . . . . This gives the manager theopportunity to stop development if the model isnot going to be useful.

Such procedures could increase an organization’scontrol over ongoing model development projects,and, if properly managed, could offer incentivesfor developers to maintain professional standardsand provide adequate user-oriented services. How-ever, additional contractual specifications inevitablyadd to the complexity of monitoring model devel-opment.

Peer Review

Peer review procedures have been proposed asa means of identifying and promoting high-qualitymodels without losing the flexibility required forinnovative modeling. Review panels, composed ofhigh-caliber professionals who are sensitive to theapplications for which individual models are de-signed, could provide valuable advice to model de-velopers, and assure sponsoring institutions of thevalue of the models they fund.

Opponents of the peer review approach cite thebureaucratic burden of establishing and maintain-ing review policies and procedures, and they ques-tion the relative value of the additional informa-tion as compared to its probable cost. These oppo-nents also point out that seasoned modeling profes-sionals are in relatively short supply—obtaining

their services for a review panel on a continuing

basis might be impossible. The use of less qualifiedreviewers for such a panel would reduce the weightand value of its recommendations.

Legal Aspects of Model Use inAdministrative Processes

Models are often used to project the effect of aproposed administrative action, Managers employ

model forecasts to minimize the possibility of caus-ing costly errors or potential damages associatedwith inappropriate decisions. Major decisions in-volving millions of dollars may be based on model-generated information. If, for some reason, themodels do not accurately simulate real conditions,administrative decisions based on model resultscould misdirect regulations, misguide managementdirectives, and misallocate capital investments.Using models in regulatory processes raises theprospect that unforeseen errors may cause adminis-trative actions to either fall short of their intendedpurpose or unreasonably burden those who are reg-ulated.

Legal issues regarding the use of models in ad-ministrative processes have arisen in three areas:1) standards for Federal judicial review; 2) judicialreview of State-level regulations; and 3) use of mod-els for planning and program development.

Standards for Federal Judicial Review

Although judicial consideration of water resourcemodels dates back to a 1943 Supreme Court caseinvolving an interstate dispute over water rights, 7

virtually all judicial notice has been in the contextof recently promulgated water quality effluent limi-tations. a Courts have also examined water qualitymodels that have been used as the basis for analyz-ing an environmental impact statement under theNational Environmental Protection Act. g

‘Colorado v. Kansas, 320 U S. 383 ( 1943)8Assoctatton ojPacJic Ftshenes ~’. E P A , 61.5 F 2d 794 (9th C ir , 1980);

Kennecott Copper V. E. P A 612 F.2d 1232 (10 Cir. , 1979); I?AS’F Wyan- {dotte Corp v. Cost[e, 598 F 2d 637 (1st Cir, , 1979); ,Vatzonal CrushedStone Association v. E P A 601 F.2d 111 (4th Cir., 1979); American Zron

and .Steef Instttute v, E P A ( 1 1), 568 F 2d 284 (3rd Cir, , 1977); FMCt. 7’razn, 539 h’, 2d 973(4th L’ir. , 1976); API V, L’ P A , 540 F’. 2d 1023(lO{h Cir., 1976); A I S 1 \ EPA (1~, 568 F,2ci 284 (3r(i Ctr., 1977),

‘ohlo Ex t?d Ilrouw L. E P A , 460 F, Supp. 248 (S L) oh,, 1978);Con~erLatton Counctl oj ,Yrorth Carollna ,, Froehlke, 435 F Supp, 7 7 5(M D N C , 1977),


Models used for agency rulemaking are adminis-trative actions reviewable by the courts. 10 Thereview standard is narrow:

As in other cases involving review of an ad-ministrative agency’s rulemaking actions we aregoverned by an ‘‘abuse of discretion’ standard—in other words, we must not substitute our judg-ment for that of the agency, but must determinewhether the administrator’s actions were ‘ ‘ar-bitrary, capricious, are abuses of discretion, orotherwise not in accordance with law . . . .‘ Inorder to facilitate meaningful judicial review, weshould require administrative agencies to ‘ ‘ar-ticulate the standards and principles that governtheir discretionary decisions in as much detail aspossible . . . . “11

Most courts reviewing models as a basis for ad-ministrative decisions rely on the standard set outin the U.S. Supreme Court case, Citizens to Preserve

Overton Park v. Volpe, 12 that a court reviewing anagency’s action should conduct a searching andcareful inquiry into the facts, but should notsubstitute its judgment for that of the agency. Thecourt held that the agency’s use of the model shouldbe accorded a ‘ ‘presumption of regularity. “13

This judicial standard has significant implicationsfor an agency’s use of models in regulation, andgrants broad discretion to the agency. When othermodels have been used to challenge an agency’smodel, the courts have examined only whether theagency’s model constitutes a ‘‘rational choice. 14Although judicial inquiry will include a thoroughevaluation of a model, it does not extend to thedetermination of the “best possible approach. ’15

l’JThe Feder~ Administrative Procedure Act provides that ‘‘exceptto the extent that—( 1 ) statutes preclude judicial review; or (2) agen-cy action is committed to agency discretion by law, 5 U. SC. sec.701 (a) ( 1976), ‘ ‘final agency action for which there is no other ade-quate remedy in a court (is) subject to judicial review. 5 U. S.C.sec. 704( 1976). For a discussion, see, D. P, Currie, ‘ ‘Judicial Re-view Under Federal Potlution Laws, 62 Iowa Law Review 1221 ( 1977).

11A. 1. S. 1. V. E P A. (1), 526 F. 2d 1027 (3d C ir., 1975).lZC1t1zen5 to prt-sovt ouerton park, Inc v. Volpe, 401 U.S. 402 416

(1971).Isol,flton Park, 401 U.S. at 415.14Cleve]and E]ec[r;c I]fuminating CO. V. E. P. A., 5~’2 F.zd 1150,

1161 (6th Cir., 1978), cert. denied, 439 U.S. 910 (1978); U.S. SteelCorp. v. E. P. A., 605 F.2d 283, 292 (7th Cir., 1979).

1 BCleLle[and Electric, 572 F. 2d at 1150, 116 1; see also, b’ermont YankeeA’uclear Power Corp v. NRDC, 435 U.S. 519, 549 ( 1977).

However, the documentation of the model mustprovide an ‘‘adequate explanation’ of the basis forthe regulation, absent which the court will over-turn the regulation.

16 What constitutes ‘‘sufficientmaterial upon which to make a reasoned decision,though, leaves a great deal of latitude to anagency. Thus, there is a disinclination to ‘‘secondguess the agency’s expert determinations as to themodel . . .

Federal courts have proved relatively flexible inapplying the ‘‘reasonable basis’ test to disputedregulations. In a case where a model simplified thesimulation of complex hydraulic flows in plasticmanufacturing plants to the degree that the rangeof flows departed from the model’s results by a fac-tor of 10, the court found no reasonable basis forthe challenged regulation. In another instance,although the court heard arguments that the chal-lenged model process differed from actual opera-tion by a factor of 5, it sustained the contestedregulation, being convinced that a reasonable ex-planation for the variation existed.20

The courts’ reluctance to involve themselves inevaluating models per se is further illustrated bya case involving proprietary models. In ClevelandElectric, which challenged the imposition of a sulfurdioxide control plan based on the use of an EPAmodel, the agency’s model was contested as inferiorto a proprietary model developed by an engineer-ing company. Although expert witnesses testifiedthat a superior method of control existed, the com-pany refused to reveal the operating details of itsmodel. As the court saw the problem:

While such withholding may be both defensi-ble as a matter of law and understandable as a mat-ter of economics, this court cannot consider En-viroplan’s model as available technology until andunless it is fully disclosed and evaluated by UnitedStates E.P.A. —the agency charged by Congresswith making these decisions. zz

~6Kmneco~t COO/MT V. E. p. A , 612 F.2d 1232, 1240 (lOth Cir,, 1979).~~A150ciation oJPul@ Fishmtes v. E. P.A , 615 F. 2d 794, 803 (9th Cir.,

1980).lapacl~ic Ftsheries, 615 F. 2d at 810.t9FA~C coTp, v, Train, 539 F, 2d 973, 980 (qth C ir. , 1976).zopacl~lc F1fhU1e5, 615 F. 2d at 810, 814.21572 F,2d at 1163.‘z Ibid,


Judicial Review of State-Level Regulations

Relatively few legal controversies have arisenover use of models by a State government as a basisfor decisionmaking. The lack of reported cases maybe partly attributable to a general lack of model useby States for regulatory purposes. Another reasonmay be the close link between Federal and Stateprograms —such conflicts may arise in the contextof the applicable Federal programs.

States have occasionally used models as evidencein administrative proceedings to determine whethera violation of an environmental control law has oc-curred; this is particularly true in the area of airpollution control .23 For instance, the Illinois Pollu-tion Control Board applied a ‘‘general theoreticalformula” to the processing data of a smelting com-pany to find the company in violation of air pollu-tion standards, However, upon review, an Illinoiscourt held that such modeling evidence was insuf-ficient to support the board’s determination.24

Litigation over regulations predicated on infor-mation from a ground water model occurred in theState of Washington in 1975. The State had devel-oped a computer model for defining maximum ratesof withdrawal and issuing new rights to groundwaters. For the Odessa area, which had been de-clared a critical ground water region, the Stateissued regulations to establish ceilings on withdraw-als with the assistance of the developed models. 25Affected ground water users disputed the accuracyof the model results;26 however, the courts upheldthe regulation. Subsequent corrections to the modelhave altered model results, though not to the degreeof affecting the regulation’s efficacy in the eyes ofState officials. Nonetheless, no further challengesto the regulation have been offered .27

23 For a discussion, see, R. A. Brazcuer, “Air Pollution Control;Sufficiency of Evidence of Violatlon in Administrative ProceedingsTerminating in Abatement Orders, ” 48 A L R 3d 795

~~.4[[ted Me[a[ C. v I[[lnou Po[[utton Control Board , 22 I ~ ~ APP. 3d

823,318 N E.2 257, 264 (1974).

Z5G. E, .Maddox, et d., ‘‘,Management of Groundwater in Eastern1+’ashington, Engineering, Geology, and Soils Symposium, 13th An-nual Proceedings, University of Idaho, Moscow, Apr. 2-4, 1975, p.201, published by Idaho Transportation Department, Division ofHighways, Boise, 1975.

ZbConversation with Alan Wald, Hydrologist, Washington Depm-ment of Ecology.

*pConversation with Charles Roe, Senior Assistant Attorney Gen-eral, Washington Department of Ecology.

Use of Models for Planningand Program Development

Probably in no other area is the use of modelsmore prevalent than in planning and program de-velopment. However, errors in planning programswhich are based solely on analysis by models canbe perpetuated in decisions made on the basis ofsuch plans. Mandated ‘‘consistency’ requirementsare potentially a major avenue for institutionaliz-ing this kind of error.

For example, the Clean Water Act requires thatthe National Pollution Discharge EliminationSystem permits issued for point sources of pollu-tion must not conflict with an approved section 208areawide management plan.28 In this manner, Con-gress established a ‘‘consistent’ planning system,linking different elements to areawide planningunder section 208. Consistency requirements alsoextend to construction of publicly owned treatmentfacilities, which must conform with the approvedsection 208 plan to be accepted.2g Section 208 plansdepend heavily on modeling. This statutory linkagebetween the areawide planning programs and reg-ulation or construction activities raises the ques-tion of whether unforeseen modeling errors in plansmay cause significant problems during implemen-tation, and subsequently lead to litigation.

An important corollary to this issue is the ques-tion of a modeler’s liability for the effects of in-accurate model results. No ruling yet exists onwhether model use involves an express or impliedguarantee that the operation of a system will sub-stantially conform to model-generated information.If an individual or organization is placed in the posi-tion of certifying compliance with regulatory stand-ards based on model results, whose responsibilityis any subsequent nonattainment of such standards?

Absent any definitive ruling on the issue, newregulatory programs involving modeling and theuse of highly sophisticated modeling analysis mayincrease the liability of the design professional. Sim-ilar problems have arisen over the professional lia-bilities of technically trained staff in other fields.The modeling community has already indicated itsconcern over exposure to liability in the context of

Zsclean water Act, sec. 208(e), 33 U. SC. sec. 1288(e).ZgC]ean Water Act, sec. 208(d), 33 U. S.C. sec. 1288(d).


certifying compliance with building energy per- Increased use of complex modeling systems, andformance standards under the Energy Conserva- layered model use to develop State ‘ ‘equivalent’tion Standards for New Buildings Act of 1976.30 standards or programs under Federal mandates,

30Milt I.unch, “DOE’s New BEPS Pose Many Legal, Liabilitymay compound initially acceptable modeling errors,

Questions for Design Professionals, ” Engineering Times, April 1980; and also increase a modeler’s potential liability.Statement of E. K. Riddick for the National Society of ProfessionalEngineers on the Proposed Building Energy Performance Standards,Mar. 24, 1980, pp. 14-16.

3 I Testimony of D, carter for the American Consult Ing F.ngineers

Council, hearings before the Senate Governmental Al’fairs Commit-tee, Nov. 20, 1979, p. 167.

Chapter 4

Federal Use and Supportof Water Resource Models

.

Contents

Page

Analysis of Current Federal Modeling Capabilities . . . . . . . . . . . . . . . . . . . . . . 67Methods Used to Survey and Analyze Federal Model Use. . . . . . . . . . . . . . . . . . . . 67Findings From the Federal Agency Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Findings From the Federal Workshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Current Approaches to Federal Model Management . . . . . . . . . . . . . . . . . . . . . 76Consideration of Models in Governmentwide Water R&D Policies . . . . . . . . . . . . 77Existing Governmentwide Mechanisms for Coordinating Modeling and

Model-Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Existing Support Structures for Agency-Level Modeling Activities . . . . . . . . . . . . . 84Agency-Level Mechanisms for Providing Information on and Access to

Existing Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Table No.3. Federal4. Agency

Models

TABLES

Page

Model Use by Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Estimates of Fiscal Year 1979 Expenditures for Water Resourceand Related Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Chapter 4

Federal Use and Supportof Water Resource Models

The Federal Government has a very broad rangeof water resource responsibilities. It is a major in-vestor in facilities to control water supplies and treatpolluted waters. It has taken the lead in programsto bring additional supplies to water-short areas ofthe country, and more recently to encourage morecost-effective approaches to water use in these areas.It has provided the legal and institutional frame-work within which States work to set water qual-ity standards and ensure that they are met. More-over, it is responsible for managing the water thatflows through the 776 million acres of the countrydirectly under Federal jurisdiction.

These responsibilities are expressed in numerouslaws, and are administered by an array of Federaldepartments, agencies, and regulatory authorities.Water resource concerns touch virtually every as-pect of the Nation’s economic, social, and politicalwell-being; thus, they are an integral part of themissions of many governmental institutions.

In analyzing Federal use of water resource mod-els, the Office of Technology Assessment (OTA)collected and evaluated information from over 20agencies and agency offices. Model use was exam-ined by agency, by authorizing legislation, by re-source issue, and by professional discipline.

ANALYSIS OF CURRENT FEDERALMODELING CAPABILITIES

Methods Used to Survey andAnalyze Federal Model Use

OTA used two primary approaches in solicitinginformation on Federal modeling efforts. It initiallyheld a 2-day workshop for Federal modelers dur-ing October 1979, to determine their views on cur-rent major problems in Federal water resourcemodeling efforts. Attended by representatives from21 Federal organizations, the workshop revealedsignificant institutional constraints to effectivemodel development and use. In preparation for theworkshops, each agency represented was requestedto provide written responses to questions regardingits current use and development of models; criticalproblem areas, appropriate roles, and reasons forusing models; anticipated future modeling needs;and current levels of monetary and personnel re-sources devoted to modeling.

At the workshop, modelers met in groups accord-ing to areas of professional expertise. Each grouplisted, discussed, and ranked the importance of its

model-related concerns. Major findings from theworkshop are summarized below; a more extensivesummary of the Federal workshop, and of a subse-quent workshop held for modelers from universitiesand the private sector, is presented in appendix A.

The second major component of OTA’s informa-tion-gathering activity was a survey of the 22 Fed-eral entities with substantive water resource respon-sibilities, conducted in June 1980. Each agency oroffice was requested to provide information on itsmodel use under more than 20 major pieces ofwater resource legislation. Respondents were askedto specify legislatively assigned responsibilities, andareas in which models are employed, according toeight general use categories: 1 ) program planning;2) promulgating regulations; 3) enforcing regula-tions; 4) complying with regulations; 5) planningor evaluating projects; 6) allocating funds; 7) tech-nology transfer; and 8) operations and manage-ment. Statistical results of this survey are tabulated

in table 3. Detailed descriptions of each agency’smodel use under specific laws and programs are

67


Table 3.—Federal Model Use by Program

Number of agencies Agencies usingNumber of agencies using models to models to meet

with program meet program programSection involvement responsibilities responsibilities

Federal Water Pollution ControlAct Amendments of 1972 (asamended by the Clean Water Actof 1977)

Grants for pollution controlprogram. . . . . . . . . . . . . . . . . . . . . . .

Mine water pollution controlprograms. . . . . . . . . . . . . . . . . . . . . .

Grants for construction oftreatment works. . . . . . . . . . . . . . . .

106

107

201

2

2

5

0

2

4

FS, BM

ESCS, CORPS,USGS, EPA-OWRS

Areawide waste treatmentmanagement. . . . . . . . . . . . . . . . . . . 208

209

7

9

6

7

EPA-OWRS, BR,FS, ESCS, SEA

BR, FS, EPA-OWRS,ESCS, NOAA,WRC, USGS

EPA-OWE, NOAA

Basin planning. . . . . . . . . . . . . . . . . . .

Water quality waivers. . . . . . . . . . . . .Water quality-related effluent

limitations. . . . . . . . . . . . . . . . . . . . .Water quality standards and

implementation plans. . . . . . . . . . .

301

302

303

2

4

6

2

1

4

EPA-OWRS

BR,FS, NOAA,EPA-SWER

Toxic and pretreatment effluentstandards. . . . . . . . . . . . . . . . . . . . .

Oil and hazardous substancesliability. . . . . . . . . . . . . . . . . . . . . . .

Clean lakes. . . . . . . . . . . . . . . . . . . . . .Thermal discharges and

exemptions. . . . . . . . . . . . . . . . . . . .Guidelines and permits for dredged

or fill material. . . . . . . . . . . . . . . . .Disposal of sewage sludge. . . . . . . .

Safe Drinking ActDetermining adverse health

effects. . . . . . . . . . . . . . . . . . . . . . . .Protection of underground sources

of drinking water. . . . . . . . . . . . . . .

307

311314

316

404405

8

46

3

77

2

13

2

11

EPA-OWRS, NOAA

USGSFS, NOAA, USGS

USGS, EPA-OWE

USGSESCS

1412

1421

1

8

1

3

EPA-DW

USGS, MINES,EPA-DW

Protection of sole-source aquifersystems. . . . . . . . . . . . . . . . . . . . . . .

Surface impoundment assessment.State program grants. . . . . . . . . . . . .Special study and demonstration

project grants. . . . . . . . . . . . . . . . . .

Toxic Substances Control ActTesting of chemical substances

and mixtures. . . . . . . . . . . . . . . . . .Regulation of hazardous chemicals

and mixtures. . . . . . . . . . . . . . . . . .

Resource Conservationand Recovery Act

Solid waste management guidelinesIdentification and listing of

hazardous wastes. . . . . . . . . . . . . .Standards for owners and operators

of hazardous waste treatment,storage, and disposal facilities. . .

Consolidated permits for hazardouswaste management facilities. . . . .

142414421443

1444

EPA-DWEPA-DWEPA-DW

111

5

111

1 USGS

4

6

4

5

1

1

EPA-PTS

EPA-PTS

1008

3001

4

4

USGS1

0

3004

3005

7

5

0

0

Ch. 4—Federal Use and Support of Water Resource Models 69

Table 3.-Federal Model Use by Program (Continued)



Grants for State resource recoveryand conservation plans. . . . . . . . .

Full-scale demonstration facilitiesgrants . . . . . . . . . . . . . . . . . . . . . . . .

Resource recovery system andimproved solid waste. . . . . . . . . . .

Endangered Species ActMinimizations of impacts of Federal

activities modifying criticalhabitats. . . . . . . . . . . . . . . . . . . . . . .

Surface Mining Control andReclamation Act

Surface coal mine reclamationpermitting. . . . . . . . . . . . . . . . . . . . .

Permit approval or denial. . . . . . . . . .Environmental protection

performance standards forsurface coal mine reclamation. . .

Soil and Water ResourceConservation Act of 1977

Data collection about soil, water,and related resources. . . . . . . . . . .

Soil and water conservationprograms. . . . . . . . . . . . . . . . . . . . . .

Water Resources Planning ActRegional or river basin plans and

programs and their relation tolarger requirements. . . . . . . . . . . . .

Coordinating Federal water andrelated land resources programsand policies. . . . . . . . . . . . . . . . . . .

Assessemnt of the Nation’s waterresources conditions. . . . . . . . . . .

Coastal Zone Management ActState coastal zone land and water

resources management programdevelopment and managementgrants. . . . . . . . . . . . . . . . . . . . . . . .

Executive Order 11988Flood plain management. . . . . . . . . .

Flood Control Act of 1936and AmendmentsFlood control structures. . . . . . . . . .

National Flood Insurance Act of 1968Identification of flood-prone areas. .

Federal Reclamation Act of 1902and Amendments

Irrigation distribution systems. . . . .Construction of small projects. . . . .

National Environmental Policy ActAdministration; EIS review and

comment. . . . . . . . . . . . . . . . . . . . . .

4008 1 0

8004 1 0

8006 3 1 USGS

7 9 3 BR, FS, FWS

506510

61

31

FS, USGS, OSMOSM

FS, USGS, BM, OSM515 6 4

5

6

6

7

2

5

FS, USGS

FS, ESCS, NOAAUSGS, BM

102 10 7 BM, BR, ESCS,CORPS, NOAA,

USGS, WRC

102

102

7

1

2

1

USGS, BM

WRC

305

2&3

6

9

2

5

NOAA, USGS

FS, CORPS, USGS,WRC, NRC

1,2,3, 7 5

2

BR, FS, CORPS,NOAA, USGS

1360 2 FEMA, SCS

(43U.S.C.421)(43U.S.C.422)

53

31

USGS, FS, BRFWS

102,103 5 5 BR, FS, CORPS,NOAA, NRC

70 ● use of Mode/s for Water Resources Management, planning, and policy

Table 3.–Federal Model Use by Program (Continued)



Atomic Energy Acf of 1954Flood protection of nuclear

facilities. . . . . . . . . . . . . . . . . . . . . . 10 CFR 50 1 1 NRCWater supply for nuclear powerfacilities. . . . . . . . . . . . . . . . . . . . . . . . 10 CFR 50 1 1 NRCLimitation of radioactive liquid to

ground and surface water. . . . . . . 10 CFR 20, 50, 61 2 2 NRC, USGS

Fish and Wildlife Coordination ActConsultation and provision of

recommendations; surveys andinvestigations. . . . . . . . . . . . . . . . . . 182 2 2 FWS, NOAA

Colorado River Basin SalinityControl Program. . . . . . . . . . . . . . . 10, 201, 202, 203 2 2 BR, SCS

Agency abbreviation key:

ASCS —C O R P S –BM –BR –DOE –EPA –

DW –OWE –O W R S –S W E R –PTS —

Agricultural Stabilization and Conservation ServiceArmy Corps of EngineersBureau of MinesBureau of ReclamationDepartment of EnergyEnvironmental Protection AgencyOffice of Drinking WaterOffice of Water EnforcementOffice of Water Regulations and StandardsSolid Waste and Emergency Response ProgramPesticides and Toxic Substances Program

ESCSFEMAFSFWSNOAANRCOSMScsSEAUSGSWRC

provided in appendix B. Insofar as OTA has beenable to ascertain, no previous governmentwidecompendium of water resource model use and ap-plication has been attempted.

These information-gathering activities were sup-plemented by OTA-commissioned reports onmodel uses, limitations, and appropriate roles infour broad water resource areas, and by telephonesurveys regarding costs associated with modelingactivities for fiscal year 1979. Estimates of fiscal year1979 expenditures for water resource models areprovided in table 4. OTA has also relied on previ-ously published studies of Federal, Canadian, andinternational model use to corroborate its generalfindings. Five of the most relevant studies are sum-marized in appendix C; individual references tothese findings are also made throughout thischapter.

Findings From theFederal Agency Survey

Table 3, which summarizes agency model useby law, and compares areas of responsibility toareas in which models are employed, provides a

———————————

Economics and Statistics Cooperative ServiceFederal Emergency Management AgencyForest ServiceFish and Wildlife ServiceNational Oceanic and Atmospheric AdministrationNuclear Regulatory CommissionOffice of Surface Mining Reclamation and EnforcementSoil Consewation ServiceScience and Education AdministrationU.S. Geological SurveyWater Resources Council

Table 4.—Agency Estimates of Fiscal Year 1979Expenditures for Water Resource Models and

Related Activities (in millions of dollars)

U.S. Geological Survey:Research. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0–4.0Application. . . . . . . . . . . . . . . . . . . . . . . . . 12.0—15.0

Army Corps of Engineers. . . . . . . . . . . . . . . 6.5—7.7National Science Foundation. . . . . . . . . . . . 2.8National Oceanic and

Atmospheric Administration. . . . . . . . . . . 2.8Department of Energy. . . . . . . . . . . . . . . . . . 0.9–1 .1Department of Agriculture. . . . . . . . . . . . . . o.7a

Department of Interior. . . . . . . . . . . . . . . . . . 4.7—5.9Environmental Protection Agency. . . . . . . . 7.8—9.4

Total. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.2—49.4alncludes estimates only from SCS and ESCS.

SOURCE: Developed from information provided in agency responses to OTAquestions regarding model use, October 1979, and from a June 1979telephone survey of selected Federal agencies. Figures include expend-itures for both research and application.

general indication of current patterns of Federalwater resource activities and model use. As mightbe expected, the more comprehensive the scope ofa water resource-related law, the greater the num-ber of agencies whose missions are affected by it.The widest-ranging of current water resource laws,the Clean Water Act of 1977, involves about 15agencies and offices, which are assigned various

Ch. 4—Federal Use and Support of Water Resource Models ● 71

responsibilities under or must comply with regula-tions stemming from 14 different sections of the law.Twelve agencies or offices indicated model useunder this act. Some laws, such as the NationalFlood Insurance Act of 1968 (Public Law 90-448),are the responsibility of a single agency—in thiscase, the Federal Emergency Management Agen-cy. On the whole, however, most pieces of Federallegislation affect more than a single agency, office,or regulatory authority.

None of the laws identified in the Federal agen-cy survey specifically require the use of models toanalyze a water resource issue. However, many ofthe analytic responsibilities specified in the legisla-

tion are routinely carried out with models. Underthe Forest and Rangeland Renewable ResourcesAct of 1974 (Public Law 93-378), for example, theForest Service of the U.S. Department of Agricul-ture (USDA) is charged with developing and imple-menting long-range land and resource managementplans for the federally owned forests under its juris-diction. It uses models that assess the effects of dif-ferent management practices on water supply,water quality, other significant natural resources,and local economic activity. The information gener-ated by these models is used in determining Na-tional Forest Management Act Regulations.

Much of the current Federal legislation directsindividual agencies to determine standards that may

72 . use of Mode/s for Water Resources Management, Planning, and policy

affect the program responsibilities of other agen-cies. Under the Clean Water Act (Public Law95-21 7), the Safe Drinking Water Act (Public Law93-523), and the Toxic Substances Control Act(Public Law 94-469), the Environmental Protec-tion Agency (EPA) regulates and sets allowable con-centrations for a number of toxic substances, organ-ic chemicals, pesticides, and other residuals. A vari-ety of models are used to determine how these sub-stances are transported to and within receivingwaters, and to estimate their effects on human andaquatic populations. Such regulations must subse-quently be incorporated into analyses performedby various agencies of USDA and the Bureau ofMines, land and forest management practices ofthe Department of the Interior (DOI) and theForest Service, and permitting processes of theNuclear Regulatory Commission for thermal ef-fluents, among others.

The findings outlined in table 3 reflect a highlyuneven pat tern of Federal model use for water re-source analysis. While some agencies use modelsto analyze a particular resource issue throughoutthe range of their statutorily assigned programresponsibilities, others use them only for a particular responsibility (e.g., complying with regulations),and still others rely solely on noncomputerized ana-lytical approaches. These inconsistencies cause suchproblems as inconsistent flood plain delineations bydifferent agencies, confusion over best managementpractices for controlling nonpoint source pollution,and disputes over projections of the amount ofwater available for energy development in the West-ern United States. Further, while highly efficientmodel-based management techniques have been de-veloped in several Federal agencies (e. g,, for operat-ing reservoirs), many agencies do not benefit fromthis already-developed expertise.

A number of factors underlie agency decisionsregarding model use. Developing a model is an ex-pensive and technically complex undertaking, in-volving highly specialized personnel requirements,extensive computer facilities, and appropriate databases. If the problem to be analyzed is not directlyrelated to the agency’s mission, the agency willoften be reluctant to commit the resources necessaryto develop a model to address the problem.

Moreover, substantial difficulties often deteragencies from adapting models that have already

been developed elsewhere in the Federal Govern-ment. When practicable, model adaptation permitssignificant cost-savings, although adequate databases and computer facilities, in addition to tech-nical assistance in adapting the model, are still nec-essary, However, information about the availabilityof many existing Federal models is not readily ob-tainable. Few agencies have taken steps to dissemi-nate information on the models they have devel-oped. In addition, Federal models are often so poor-ly documented that a manager cannot determinetheir suitability for use by his agency.

Findings From the Federal Workshop

Although Federal agency modelers met and dis-cussed issues in four separate professional group-ings—l) surface water flow and supply; 2) surfacewater quality; 3) ground water; and 4) economic/social-the majority of their concerns were not spe-cific to these areas, but encompassed the broaderproblem of providing adequate and appropriate in-stitutional support for modeling activities ingeneral. Indepth summaries of modelers’ delibera-tions on such issues as research and development(R&D) needs, data needs, documentation, valida-tion, technology transfer, model maintenance, theutility of model clearinghouses, and interagencycoordination, are provided in appendix A.

Participants ranked the following issues as beingamong the most significant of those discussed:

●

●

●

●

●

●

The

collecting accurate and adequate data todevelop, test, and apply models;improving decisionmaker understanding 01general capabilities and limitations of models;improvements in user support, training inmodel use, and analysis of results;greater emphasis on documentation of models;improved planning and resources for modelmaintenance and management;making federally developed models known andavailable to other Federal agencies and to thepublic; andimproving coordination among agencies formodel development and use.

significance of these issues to water resourceanalysis and problem-solving capabilities at the Fed-eral level is discussed below.


Data Availability

The availability of sufficient data to characterizea physical system is critical to modeling it successful-ly. Computer models are often highly data inten-sive, requiring independent data sets for develop-ment, calibration, verification, and applicationphases. Workshop participants pointed to the ex-pense of collecting water resource data as a majorlimiting factor in constructing models.

Most existing Federal data bases are created toserve program purposes rather than for researchand analysis per se. Developers consequently findmuch of the existing data unsuitable for modelingactivities. Participants suggested coordinated ap-proaches to data collection and model development,as well as sensitizing model developers to the poten-tial data requirements (and costs) of their models.Emphasis was also placed on the need to improveaccess to existing data bases, and improve the costeffectiveness of future data collection efforts, par-ticularly through interagency coordination and database consolidation.

Coordinating and integrating data collection ona governmentwide basis is a major Federal manage-ment issue, and concerns many informational pur-poses in addition to modeling efforts. Consequently,an indepth analysis of Federal data-gathering activi-ties is beyond the scope of this report. However,results from the OTA workshop and surveys, aswell as surveys of federally developed models bythe National Science Foundation (NSF)l and theGeneral Accounting Office (GAO),2 indicate thatmodelers and managers alike consider problems inobtaining data to be the most prevalent limitationon model development efforts. Three of the fourOTA workshop groups considered this to be theirtop priority concern, while respondents to the GAOsurvey attributed one-fifth of all identified model-ing problems to data availability. Any future at-tempts to improve Federal data-gathering practicesand procedures will have major effects on the mod-eling community. Input from this communityshould be solicited in data collection planning to

‘Gary Fmmm, William L. Hamilton, and Diane E. Hamilton, Fed-erally Supported Mathematical Models Survey and A nalysls, under contractwith the Division of Social Systems and Human Resources of the Na-tional Science Foundation, June 1974.

2 Ways to Improue Management oj Federally Funded Computerized Models,General Accounting Office, August 1976.

minimize additional data-gathering costs associatedwith future modeling efforts.

Improving DecisionmakerUnderstanding of Models

Information gaps between decisionmakers andmodelers were among the top three priority con-cerns for all four modeling groups at the OTA Fed-eral workshop. Workshop participants focused onthe relationship between modeling and the decision-making process as a major deficiency in currentFederal modeling practices. Upper-level managerswere characterized as being unaware of basic mod-eling concepts and of the limitations and capabilities

of the specific models they use. Modelers pointedto a lack of mechanisms throughout the FederalGovernment for bringing managers and modelers

74 ● Use of Mode/s for water Resources Management, Planning, and policy

together to plan and develop models. Such a lackof interaction was seen as a major contributor tomanagement-level mistrust of models, and the in-adequacy of current levels of support for planninglong-range model development, documenting andmaintaining models, and providing user services.

These findings are strongly in accord with thosefrom earlier studies. The survey of 222 nondefenseFederal models conducted in 1974 for NSF foundhighest rates of failure in modeling projects designedto provide information to policy makers. The lowutilization rate of such models was attributed pri-marily to lack of communication between modelbuilders and potential policy makers during modeldevelopment, and secondarily to policymakers’ lim-ited understanding of models that had already beendeveloped. 3 Similarly, one-fifth of modeling prob-lems identified in the GAO survey (1976) were at-tributed to ‘‘lack of management acceptance andknowledge of modeling techniques.”4

Integrating the needs of decisionmakers intomodel development processes is especially criticalif models are to be used effectively at agency deci-sionmaking levels. Federal managerial personneloften have a great deal of discretion over what pro-cedures to employ in analyzing an issue. Some mayhave obtained favorable results from modeling inthe past, while others may have been ‘‘burnt’ byrelying on the accuracy of model-based informa-tion. Since the Federal Government provides noguidelines regarding model uses for analytical pur-poses, and offers very little management-leveleducation in model use and interpretation, deci-sionmakers are generally ‘ ‘on their own’ indeciding when to commit their agencies to model-ing efforts.

In practice, Federal agencies tend to commissionmodels in response to a specific problem, when adecisionmaker becomes aware of the need for other-wise unavailable information. All too frequently,however, Federal modelers are given little instruc-tion regarding the nature of the desired informa-tion, and are not provided access to the individual(s)who must act on the information generated. Tech-nically sophisticated, yet impractical models often

3Fromm, Hamilton, and Hamilton, op. cit., pp. 3-7, 51-54‘General Accounting Office ( 1976), op. cit. , p, 37.

result, and are quickly abandoned to agency ar-chives.

User Support

Participants in the OTA modeling workshop fre-quently asserted that Federal modeling efforts haveoverconcentrated on model development, and de-voted inadequate resources to transferring model-ing technology and expertise to potential users. Allfour workshop groups placed some aspect of userservices among their top three priorities. Many par-ticipants stated, however, that current agency ca-reer evaluation systems discourage modelers fromproviding such technology transfer to model users.While incentives are provided for developing in-creasingly sophisticated models, no incentive struc-ture currently encourages modelers to aid users inunderstanding, running, and interpreting the re-sults of such tools.

Workshop participants singled out three majoraspects of technology transfer as needing additionalattention and resources: 1 ) documentation; 2) train-ing in model use and interpretation; and 3) techni-cal assistance. Most participants appeared to con-sider documentation the most critical of technologytransfer needs. Because documentation is time con-suming and expensive to produce, decisionmakersand modelers alike have tended to assign it low pri-ority, concentrating on the production of ‘bottom-line’ information. Without adequate documenta-tion, however, decisionmakers cannot subsequentlydetermine how the information was generated, norevaluate it. Documentation is also crucial for pro-viding individuals in other Federal agencies a meansof determining whether they can use a previouslydeveloped model. A 1974 GAO survey of 710 Fed-eral data-processing personnel and auditors whoreported problems due to inadequate documenta-tion, revealed that nearly one-third (233) of therelated programs had to be totally rewritten, andone-sixth (1 27) of the automated data-processingsystems had to be redesigned. Moreover, more thanhalf (428) of the documentation-related problemsresulted in substantial delays in the completion ofassignments. 5

51mprowrmmt .Vee&d m Documenting Computer [email protected], General Account-ing Office, October 1974, pp. 6-7.


Concern over the inadequacy of current levelsof documentation for Federal models is corrobo-rated by the 1974 NSF survey, and by a 1979 sur-vey of 39 modelers conducted for the NationalBureau of Standards (NBS). NSF found that forabout 75 percent of the 222 surveyed models, thedocumentation supplied by the developer was in-adequate to enable nonproject personnel to set upand run the model. G Developers surveyed by NBSshowed strong support for governmentwide modeldocumentation guidelines, including the specifica-tion of a documentation plan in model developmentcontracts, detailing the documents to be produced,the resources allocated, and personnel responsibil-ities. 7

Training opportunities are essential to developingin-house capabilities for running and interpretingmodels. Unless training is supplied, agencies aretotally dependent on model developers for model-generated information. The 1974 GAO surveyfound the third-largest source of major modelingproblems to be “lack of qualified personnel tooperate and maintain the model. Workshop par-ticipants were similarly concerned to find ways ofencouraging agencies to provide adequate resourcesfor model-related training, Different levels of train-ing for decisionmakers and for users were repeated-ly advocated, the latter type to incorporate “hands-on ‘‘ interaction with the model and ‘ ‘one-on-one’instruction where possible.

Workshop participants also pointed to the routineprovision of technical assistance as an inexpensivemeans of troubleshooting in model use, The avail-ability of knowledgeable individuals to answer sim-ple ‘ ‘over-the-phone’ questions can save man-hours and computer time that are otherwise lostto trial-and-error attempts to operate the model.For more complex models and/or modeling prob-lems, participants suggested temporarily assigningdevelopers to user organizations to facilitate the ini-tial setting-up of the model.

bFromm, Hamilton, and Hamilton, op. cit. , p. 6.‘Saul I Gass, ‘ ‘Assessing Ways to Improve the Utility of Large-

Scale Models, ‘‘ in Valldutlon and Assessment Zssues of Ener~ Models, ~’a -tional Bureau of Standards, Special Publication 569, February 1980,p, 251.

Maintenance and Dissemination

The current structure of Federal modeling activ-ities gives agencies little incentive to consider poten-tial uses for models once they have served the agen-cy’s primary purpose. Consequently, most modelsare not updated, or maintained, to keep them tech-nologically current, nor is information about theirexistence or availability circulated among poten-tial users in government and the private sector. Oneof the most frequently voiced concerns of workshopparticipants was the difficulty of locating and ob-taining existing Federal models. Many modelersconsidered improving access to current models ahigher priority than improving and developing newones. Participants generally agreed that lack of in-formation regarding the availability of Federal mod-els is a significant barrier to their widespread use.

Participants also noted the Federal Governmentlack of commitment to maintaining the models ithas already developed. They stressed the need todevelop mechanisms and/or organizational unitswith routine responsibilities for periodic modelanalysis and updating. The need to inform modelusers of changes made to a model was also consid-ered to be neglected in current agency procedures.

Interagency Coordination

Federal modelers identified the lack of interagen-cy coordination as a major bottleneck in efforts toadvance the state of the modeling art. Managerstend to be unaware of the modeling and model de-velopment projects being supported by other agen-cies, a situation that may lead to decisions to buildmodels already in existence or in process of develop-ment. A certain amount of duplication in model-ing has potentially beneficial effects—it fosters akind of competition from which more accurate andefficient modeling techniques can result. However,for highly complex modeling tasks, interagencypooling of resources and technical expertise couldfacilitate greater and more rapid advances than arepossible when each agency functions independently.As explained in a USDA Soil Conservation Serv-ice background paper for the OTA modeling work-shops, “There would be value in encouragingbroader use of certain water resource models among

76 ● Use of Mode/s for water Resources Management, Planning, and policy

Photo credit: @ Ted Spiegel, 1982

Federal agencies with modeling expertise and computing facilities provide extensive assistance to State and localusers, as well as to users in other Federal offices. Miniature lights on these panels at USGS computer facilities in

Reston, Va., glow when telephone hookup lines to computers are currently in use

Federal agencies both to reduce duplication of mod- only means of assuring that high-quality models arecling effort and to obtain the benefit of multiple brought to completion. The creation of adequateagency comment following their use. data bases to support sophisticated modeling proj -

Further, for highly complex and interdisciplinaryects, in particular, calls for interagency coordina-tion and planning.

modeling, interagency participation may be the

CURRENT APPROACHES TO FEDERALMODEL MANAGEMENT

This section reviews the Federal legislation and arrangements currently responsible for disseminat-program activities that affect the development and ing water resource models and/or assisting otheruse of water resource models. It analyzes the plan- water resource agencies to use them. Because mod-ning framework through which funding is provided cling is an integral part of Federal responsibilitiesfor model-related work. This section further defer water resource analysis, data collection, andscribes the major organizational and institutional R&D, this section also addresses a number of Fed-


eral agencies and offices for which the advancementof modeling capabilities is not a primary objective.The section is organized according to four majorareas of Federal involvement: 1 ) governmentwidewater R&D policies; 2) governmentwide coordina-tion and dissemination activities; 3) agency-levelmodeling activities; and 4) agency-level dissemina-tion activities.

Consideration of Models inGovernmentwide Water R&D Policies

The Water Research and Development Actof 1978

The Water Research and Development Act of1978 is currently the major legislative mechanismfor coordinating the development of analytical toolsto address water resource issues. It states the con-gressional finding that ‘‘the Nation’s capabilitiesfor technological assessment and planning and forpolicy formulation for water resources must bestrengthened at both the Federal and State levels,and assigns responsibilities to the President and theSecretary of the Interior for developing a coordi-nated Federal program of water-related researchand technology.

The act directs the President to:

Clarify agency responsibilities for Federal waterresources research and development and providefor interagency coordination of such research, in-cluding the research authorized by this Act. Suchcoordination shall include: 1 ) continuing reviewof the adequacy of the Government-wide programin water resources research and development andidentification of technical needs in various waterresources research categories, 2) identification andelimination of duplication and overlaps betweentwo or more programs, 3) recommendations withrespect to allocation of technical efforts among theFederal agencies, 4) review of technical manpowerneeds and findings concerning the technical man-power base of the program, 5) recommendationsconcerning management policies to improve thequality of the Government-wide research effort,and 6) actions to facilitate interagency communica-tion at management levels (sec. 406(b)).

In addition, the act assigns specific responsibilityto the Secretary of the Interior to:

Develop a five-year water resources researchprogram in cooperation with the (state water re-search) institutes and appropriate water entities,indicating goals, objectives, priorities, and fundingrequirements (sec. 103 (b)).

To fulfill these objectives, and other objectives ofthe act:

The Secretary shall cooperate fully with, andshall obtain the continuing advice and cooperationof, all agencies of the Federal Government con-cerned with water problems, State and local gov-ernments, and private institutions and individuals,to assure that the programs conducted under thisAct will supplement and not duplicate other waterresearch and technology programs, will stimulateresearch and development in neglected areas, andwill provide a comprehensive, nationwide programof water resources research and development (sec.406 (a)).

In assigning responsibility for developing a com-prehensive 5-year water resources research programto the Secretary of the Interior, the act broadly

outlined a new mechanism for coordinating Federalwater resources analysis. Between 1963 and 1977,such a task had been the responsibility of the Com-mittee on Water Resources Research (COWRR),under the aegis of the Federal Council for Scienceand Technology within the Executive Office of thePresident (EOP). Beginning in 1966, COWRR de-veloped and annually updated a long-term programfor water resources research. Its reports recom-mended priority research areas and were intendedto guide Federal agencies in allocating researchfunds.

The 1978 act calls, in general terms, for EOPto play a lead role in coordinating the conduct ofwater resources analysis among the Federal agen-cies, relying on DOI to develop a research and technology agenda as a basis for EOP decisions. Presi-dent Carter’s message on science and technology,delivered to the Congress on March 27, 1979, fur-ther directed the Secretary of the Interior and theDirector of the Office of Science and TechnologyPolicy (OSTP) to determine research priorities formeeting the Nation’s long-range water needs.

78 ● Use of Models for Water Resources Management, planning, and policy

Development of the Five-Year WaterResources Research Program

Under the joint direction of DOI and OSTP, in-teragency policy and working groups summarizedcurrent agency-level programs of water reseach andshort-term priorities in ‘‘Water Research Prioritiesfor the 1980’s” (April 1979),8 and developed rec-ommendations for improving the Federal effort in10 broad subject areas in ‘ ‘Interim Report—Pri-orities in Federal Water Resources Research’(August 1979).9

“Proposed U.S. National Water Resources Re-search, Development, Demonstration, and Tech-nology Transfer Program, 1982-87, draft, an ex-panded version of the agency summaries with pro-jected funding levels for fiscal years 1982 to 1987,was delivered to the Water Resources Research Re-view Committee of the National Academy of Sci-ences (NAS) for review in December 1980. TheNAS evaluation, Federal Water Resource.s Research: A

Review of the Proposed Five- Year Program Plan, was

published in May 1981.

Water resources models figure prominently inthe description of agency research efforts in theApril 1979 and December 1980 documents. Theextent of the Federal commitment to modeling ac-tivities is exemplified by frequently occurring refer-ences to them in many of the agency reports. EPA,for example, lists among its research priorities theneed to:

develop, test and validate models for simulat-. . .ing source loads and ‘‘ in-stream’ processes for usein assessing water quality problems, allocatingsource loads, and evaluating alternative manage-ment strategies; and expand modeling capabilityto include toxics, especially with regard to sedimentprocesses. 12

8 ’ ‘Water Research Priorities for the 1980’ s,” Department of theIntcrlor, Office of Water Research and Technology, April 1979.

9 “ Interim Report-priorities in Federal Water Resources Re-search, Department of the Interior and the Oflice of SC icncc andTechnology Policy, August 1979.

‘0’ ‘Proposed U.S. N’ational Water Resources Research, Develop-ment, Demonstrate ion and Tmhnolo,gy Transfer Program, 1982-1987,D r a f t , Department of the Interior, December 1980.

~ ~ Ftdma[ Walu ResOurce3 Re~earch A Review of the Proposed Flue- YearProgram Plan, Water Resources Research Review Committee of the,National Research Council (Washington, 1). C. : National A( acfemyPrrss, 1981),

1“ ‘Water Rescm-ch Priorities f’or the 1980’ s,” p.67,

Agencies also report needs for information andmodels in areas where, lacking authorization tofund model development, they must rely on themodeling effort of other agencies. The Soil Con-servation Service of USDA pointed out the need‘ ‘to improve estimates of erosion potential andnutrient loss from forest and rangelands; similarly,the Department of Transportation stated that itcould benefit from work to “develop operationaltwo-dimensional model simulating stream degrada-tions, aggravation, and local erosional processes.

Both documents are compendiums of individualagency research plans; consequently, opportunitiesfor interagency coordination of modeling efforts,or other research and technology-related activities,are not addressed. In addition, neither documentdescribes agency activities in sufficient detail to per-mit a determination of levels of funding allocatedto modeling activities, or the means used to coordi-nate modeling and related support efforts withineach agency. No summary of State needs was in-cluded in either document, and it is difficult todetermine how or whether the State water resourcesresearch institutes’ 5-year programs were con-sidered in formulating the agency research plansthat constitute the December 1980 draft.

The ‘ ‘Interim Report’ of September 1979 setsout goals and general priorities for governmentwidewater resources R&D. It indicates many areas inwhich improved modeling capabilities are needed,including conjunctive ground water/surface watersystems, aquatic ecosystems, environmental im-pacts to wetlands, chemical transport, verificationof water quality and wasteload allocation models,flood plain delineation, streamflow forecasting, andhydrological/meteorological forecasting. No attemptis made, however, to relate general goals to specificagency activities, or to recommend divisions of re-sponsibility and funding allocation levels amongagencies. The report provides broad guidelines toagencies conducting research and analytical activ-ities, but addresses none of the management con-cerns outlined in the 1978 act.

The differences between the two agency compila-tions and the ‘ ‘Interim Report’ suggest one of themajor difficulties in creating an overall Federal

‘ ‘Ibid, p. 9.141hid, p. 63.


strategy for water resources R&D. From the per-spective of each Federal agency or program, modelsand research are valuable primarily for their con-tribution to specific program objectives. Alter-natively, an overview of national water resourceproblems can show areas in which lack of computer-based information prevents important advances inidentifying needs, creating cost-efficient controlstrategies, and developing better administrative andlegislative tools, Making agencies more responsiveto such national-level concerns requires concerted,ongoing efforts at highest management levels to in-tegrate overall objectives into routine agency deci-sions and funding allocation procedures.

The NAS evaluation of the proposed 5-year pro-gram plan also sets out to define broad problemareas in which further water resources research isneeded. It focuses, however, on analyzing inade-quacies in the December 1980 draft, and identify-ing institutional constraints to the development andimplementation of a coordinated long-range Federalplan. The NAS study points out the inadequaciesof a focus on research per se—rather than on abroader range of analytical and support needs—as a major defect in the DOI/OSTP coordinatingeffort.

The report by its title purports to cover morethan ‘ ‘water research’ ‘—namely, ‘‘development,demonstration, and technology transfer, ’ althoughthese terms are not defined. Rigorous attention isnot given to distinguishing those separate activitiesin the program statements of the individual agen-cies, and no overall assessment of these activitiesis included in the program. The instructions to theagencies mentioned only research. 15

The NAS study further concludes that the direc-tives of the 1978 act are insufficient in themselvesto provide a basis for coordinated Federal ap-proaches to water resource R&D.

The deficiencies noted in the draft of the five-year program report are convincing evidence thatthe ad hoc approach to management of the Federalwater research program will not yield the resultsexpected by Congress whenResearch and Development

it enacted the WaterAct of 1978.16

OTA’S survey of Federal water resource model-ers and of related studies suggests that directivesfor formulating an overall Federal plan for waterresearch and technology should specifically addressthe relationship between research and developingusable analytic tools. Priorities and allocation offunding and manpower need to be set for both kindsof activities, as well as for mechanisms to transfermodeling expertise and increase model availabil-ity to Federal, State, local, and private sector users.

Role of the State Water Resources ResearchInstitutes in Coordinating FederalWater R&D Policy

The Water Resources Research Act of 1964, andits successor, the Water Research and DevelopmentAct of 1978, provided for the establishment of anetwork of State water resources research institutesat a designated land-grant college or university ineach State. Under the auspices of the Office ofWater Research and Technology (OWRT) in DOI,the institutes have funded a wide variety of researchprograms in water resources. Since its inception,the State Institute Program has involved over35,000 professionals and students in water-relatedresearch and problem-solving studies. Funding hasbeen provided by OWRT on a matching basis withState governments under two separate programs:1) a basic allocation of $110,000 per State (as offiscal year 1980), and 2) a competitive grants pro-gram allotting a total of over $5 million (as of fiscalyear 1980). However, for fiscal year 1982, the com-petitive grants program has been eliminated, whilethe basic allocation to individual States has beenreduced to the $110,000 1980 figure. In addition,OWRT has been scheduled for elimination, andits duties and responsibilities transferred to otheroffices and programs, before the end of the currentfiscal year.

The State Institute Program has proved to be anefficient, effective means of encouraging a widevariet y of water research efforts. In fiscal year 1979,the latest year for which detailed cost statistics areavailable, total Federal support of slightly over $21million elicited a nearly equal commitment of State

—.—‘I ~“l’herC arc ‘ urrf.nt]~, 51 lnst itutcs-onc pcr state, and add itlt}na!]nst ltut ions in }$’ashlnqon, D.C , Puerto Rico, Guam, and [hc \’lrgtnIslands.


and private funds. During that year, the programsupported the work of about 1,200 principal investi-gators and about 1,750 student research assistants.Modeling activities constitute an important com-ponent of institute efforts, and increased trainingopportunities in model-related skills for waterresource professionals have been one of the pro-gram’s major byproducts.

The 1978 act also designates the institutes as theprincipal source of information regarding Statewater research needs for use in creating the Federal5-year program plan. Each institute is required tosubmit to the Secretary of the Interior for approvalan annual program “developed in close consulta-tion and collaboration with leading water resourcesofficials within the State’ and ‘‘to cooperate withthe Secretary in the development of five-year waterresource research and development goals and objec-tives.

The scope of institute activities varies greatlyfrom State to State. Some institutes focus on ana-lytical work in cooperation with State water agen-cies; others concentrate on more traditional researchfunctions. The diversity of the activities and con-cerns of the 54 State institutes is highly appropriateto their research missions, but has mixed implica-tions for relaying State agency needs in water re-source R&D to Federal policymakers. The institutesare closely connected to the academic institutionsat which they are housed, and are not alined withany one State agency. Their freedom from mission-oriented concerns and priorities gives them the po-tential to represent the needs of all the State-levelwater resource agencies. However, since the insti-tutes are staffed primarily by research scientists withprofessional ties to universities, they are not in-volved with day-to-day State agency problems.

Existing GovernmentwideMechanisms for CoordinatingModeling and Model-Related

Information

Office of Water Data Coordination (OWDC)

Since water resource modeling tends to be highlydata-intensive, model developers and users are par-ticularly vulnerable to problems of data availabil-ity. Unless the collection of required data can be

planned simultaneously with model development,modeling activities must be adjusted to the availabledata resources. This makes coordination of waterdata collection extremely important to successfuluse of water resource models.

Hydrologic data are collected by a large numberof governmental and private entities, normally inorder to serve some specific informational purposeor in support of established program activities. His-torically, such data were collected under methodsand standards devised to suit an organization’s oragency’s individual purposes, and were stored awayonce the organization’s needs for it were met. Whilesome general-purpose data on the quality and quan-tity of the Nation’s available water resources wereroutinely collected and disseminated by the WaterResources Division of the U.S. Geological Survey(USGS), potential users of water data frequentlyencountered difficulty in identifying and locatingexisting data bases. Afterwards, even when suchdata were located, they were often found unusable,due to collection methods and/or standards of accu-racy that failed to meet user requirements.

In 1964, to aid in coordinating water resourcedata, the Office of Management and Budget (thenthe Bureau of the Budget) issued Circular A-67,assigning the role of lead agency for such activitiesto DOI, which assigned specific responsibility forthis function to USGS. To carry out this responsi-bility, USGS created OWDC, and gave it the fol-lowing principal responsibilities:

exercising leadership in achieving effective co-ordination of water data acquisition activities;undertaking continuing and systematic reviewof water data requirements and activities;preparing and keeping current a Federal Planto aid in coordinating agency water-data ac-quisition efforts;maintaining a central Catalog of Informationon Water Data and on Federal activities beingplanned and conducted to acquire water data;anddesigning and operating a national networkfor acquiring data on the quality and quanti-ty of ground and surface waters, including thesediment loads of streams.

Major programs of OWDC most relevant tomodeling needs include:


Photo credit: @ Ted Spiege/, 7982

Banks of disk-drive units retrieve and store information at USGS headquarters in Reston, Va.

Federal Plan. —A key coordination document,summarizes the plans and needs of agencies acquir-ing or using water data. It brings these planstogether at the level of each of the 21 nationalregions of the Water Resources Council—the re-gional plans are then assembled as the basis for theunified Federal Plan. Ongoing field-level reviewand Interagency Advisory Committee oversight areemployed to achieve coordination at local and na-tional levels.

Catalog of Information on Water Data.—Acomputerized file of information about water dataactivities. Currently, the catalog is divided into foursections: 1) streamflow and stage; 2) quality of sur-face water; 3) quality of ground water; and 4) aerial

‘8’ ‘Plan for Water Data Acquisition by Federal Agencies Throughfiscal year 1982, Office of Water Data Coordination, USGS, Depart-ment of the Interior, August 1980.

investigations and miscellaneous activities. Specialindexes such as the four-volume ‘‘Index to Stationsin Coastal Areas’ have also been published. An-other special index currently being prepared coverswater data acquisition activities in the major coalprovinces of the United States.

National Water Data Exchange (NAWDEX).—A national confederation of water-orientedorganizations working together to improve accessto water data. Developed by a working group ofthe Interagency Advisory Committee on WaterData, it has a function which the Catalog of Infor-mation on Water Data only partially fulfills-thatof assisting users of water data in identifying, locat-ing, and acquiring needed data. NAWDEX mem-bers are linked so that their several water dataholdings may be readily exchanged for maximumuse. Coordination and overall management for the

82 . Use of Models for Water Resources Management, planning, and policy

program is provided by a central program officewithin the Water Resources Division of USGS.

Water Resources Scientific Information Center(WRSIC)

An early priority of COWRR was the establish-ment of a central facility to collect and disseminateinformation relating to water resource analysis. Inresponse to its recommendations, under the author-ity of the Water Research and Development Actof 1964, DOI created WRSIC within OWRT (thenthe Office of Water Resources Research) in 1966.

WRSIC is primarily a management and supportunit that funds the compilation of information byother organizations. It does not collect and storepublished material, nor does it have a staff of ab-stracters, indexers, and support technicians. It con-tracts with a variety of governmental and privateorganizations to collect information under serviceand funding agreements, and produces publicationsand computerized records by arrangement with ad-ditional government organizations. Its two majorinformation systems have been the Selected Water Re-sources Abstracts (SWRA) and the Water ResourcesResearch in Progress File. Recent budget reduc-tion initiatives have cut WRSIC appropriationsfrom over $900,000 for fiscal year 1981 to under$600,000 in fiscal year 1982, and have eliminatedWRSIC support for the Research in Progress File.

Material for SWRA is collected primarily by pri-vate centers of competence in particular water re-source fields, supplemented by additional informa-tion from Federal agencies, State water resourcesresearch institutes, and a commercial abstractingservice. The material is processed at the NationalTechnical Information Service (NTIS), and madeavailable in two forms: a journal, SWRA, pub-lished semimonthly, and computerized biblio-graphic retrieval services available through DOIand private sources. Approximately 15,000 newbibliographic entries are published and added tothe system each year. The abstracts system current-ly holds over 150,000 full bibliographic references.WRSIC also uses the system to produce and publishan extensive topical bibliography series, and theOWRT research reports.

The Water Resources Research in Progress File Catalogis an annual compilation of about 2,500 summary

descriptions of new or substantially revised researchprojects in water resources. Until October 1981,the file was compiled by the Smithsonian ScientificInformation Exchange (SSIE) from material volun-tarily registered there by Federal and other researchorganizations. NTIS has recently been given re-sponsibility for compiling the Research in ProgressFile, and is developing procedures to streamline thecompilation process. Since file entries refer to ongo-ing work, the file reports projects substantially inadvance of SWRA, which can reflect only publishedfindings. File information is accessible throughcomputer retrieval systems at NTIS and throughthe private sector.

Both the Research in Progress File and SWRAcontain information about models and modelingactivities. However, since they are designed formuch broader purposes, abstracts and researchprojects are referenced originally by subject areas—and are cross-referenced only under the generalcategory, ‘‘model studies. It would be extremelydifficult for these general bibliographic referenceservices to adequately address the specialized natureof modeling needs without making substantialchanges in their capabilities—such as the ability tostore and distribute computer programs.

National Technical Information Service

NTIS of the Department of Commerce servesas the primary source for the public sale of Govern-ment-sponsored research, development, engineer-ing reports, machine-processable data and relatedsoftware. It adds approximately 70,000 new reportsannually to an information collection of over 1 mil-lion titles, of which over two-thirds are computerretrievable. NTIS publishes a number of user-infor-mation reports to keep users informed of availablematerial, including a comprehensive biweekly jour-nal summarizing new publications, 26 weekly ab-stract newsletters, with annual indices, and over2,000 bibliographies. NTIS analysts are also avail-able to match user requests to available material,using online computerized master files.

In addition, the statutory mission of NTIS in-cludes the collection and sale of data files and com-puter programs from Federal sources. These aremade available to users on magnetic tape, whiledocumentation in the form of user and program-


ing manuals is available in printed copy or onmicrofiche. Models must already be documentedin order to be listed in NTIS files. Computer-basedmaterial is primarily indexed under the subjectarea(s) to which it refers—a retrieval system wasdeveloped specifically for locating computer tapesof models, but was poorly suited to this purpose.More recently, NTIS files of computer models havebeen combined with those of the General ServicesAdministration (GSA) Federal Software ExchangeCenter (FSEC), as described below.

Following the elimination of SSIE, NTIS has re-cently been designated to compile the Research inProgress File, the water research portion of whichwas previously funded by WRSIC. As no fundingwas allocated to NTIS for compiling the file, theagency can only accept Notifications of Researchin Progress for which submitting agencies have pro-vided indexing and other preparatory work for com-puter retrieval.

Because water resource models constitute onlya minute fraction of the entries in the NTIS system,proposals for increasing general NTIS capabilitiesto locate them and advise potential users about theirfunctions are difficult to justify. As a general-pur-pose information center that is obligated by law torecover its costs from sales and distribution of prod-uct and services, NTIS cannot affort to serve asa modeling resource center. With regard to com-puter programs, it can be an effective mechanismfor the distribution of an already-known model, butits functions are too broad to permit its effectiveuse as a focus of modeling expertise and informa-tion.

GSA Federal Software Exchange Center

The Brooks Act of 1965 (Public Law 89-306)gives GSA authority to develop governmentwideguidance for automatic data-processing activities.Under this authority, GSA amended the FederalProperty Regulations to create a Federal SoftwareExchange Program in February 1976. To imple-ment the program, GSA created FSEC by inter-agency agreement with NTIS, using funding fromthe GSA automatic data-processing revolving fund.

The Federal Property Management Regulationsrequire agencies to submit abstracts of computerprograms considered usable by other agencies to

FSEC at NTIS. The regulations specify that thesecomputer programs must have been operational forat least 90 days, and require agencies to provideparticular forms of documentation with the ab-stracts. FSEC currently compiles the submitted ab-stracts into the GSA Software Exchange Catalog, andsets prices for Federal, State, and local governmentagencies wishing to use the listed computer pro-grams. Subscriptions to the catalog are providedfor a $75 annual fee.

No mechanisms exist, however, for enforcingparticipation in the software exchange program.The determination of which programs are suitablefor interagency use rests with each agency, andGSA has authority to do little more than persuadeagencies to submit abstracts. Consequently, re-sponses to the program have not met expectations—while GSA and NTIS officials planned for thereceipt of up to 7,000 abstracts in fiscal year 1977,the first year of the center’s operation, the inven-tory currently contains only about 1,300 abstracts,a small percentage of the software suitable forexchange.

For a program to be included in the Software Ex-change Catalog, agencies must submit a tape of theactual program, documentation, and an informa-tion sheet specifying basic program characteristics.All software packages are routinely reviewed forcompleteness, but FSEC staffing levels do not gen-erally permit the evaluation of submitted programs.Consequently, the FSEC inventory consists primar-ily of general submissions of unknown quality. Onlya very small percentage of inventoried programshave been tested and enhanced by GSA, or are con-sidered to be of special significance and known reli-ability. Moreover, to satisfy agency fears about re-ceiving large numbers of direct inquiries regardingcomputer programs, software exchange programregulations further specify that the developer of sub-mitted computer programs will not be identified topurchasers without the developer’s prior consent.

Providing technical assistance to users has notbeen included as a major part of the FSEC mis-sion—less than one staff-year of time was budgetedfor this purpose for the first year of the center’soperation. GSA’s policy of recovering the costs ofthe program through sales of computer software ap-pears to preclude higher levels of assistance. How-

84 . Use of Models for Water Resources Management, planning, and policy

ever, since potential users frequently have no ac-cess to developers under the program, many avail-able models will remain unused for lack of the tech-nical guidance required to adjust them to particularuser needs. An early GAO report on FSEC activi-ties (1978) summarizes:

The GSA Software Exchange Program, as pres-ently operated, is primarily a catalogue sales opera-tion. In our opinion, many agencies will not buysoftware from this source because adequate techn i-cal assistance is not being provided.

To enhance intra-agency software use, and ex-pand the base for submissions to the FSEC inven-tory, FSEC has recently begun to offer technicalassistance to Federal agencies on a reimbursablebasis for establishing internal software inventories,and setting up coordination mechanisms for soft-ware development and use. FSEC is also nego-tiating with various specialized groups to catalogsoftware in topical categories, geared to specificclasses of users.

Existing Support Structures forAgency-Level Modeling Activities

The majority of Federal agencies that currentlyuse water resource models lack comprehensive strat-egies for developing, using, and disseminating thesetools. Modeling activities and expertise are dis-persed throughout most of the agencies surveyedby OTA, with little apparent coordination, commu-nication, or sharing of resources among individualmodeling projects. However, two of the major usersof water resource models—the Corps of Engineersand USGS—have developed programs that inte-grate all major phases of modeling activity, andfunction as a focal point for serving the modelingneeds of nonagency users.

The two organizations employ widely divergentapproaches for supporting model-related activities.The Hydrologic Engineering Center (HEC) of theCorps of Engineers is a discrete organizational unitthat develops and supports a limited number 01 care-

fully selected models for use in a wide variety of ap-plications, By contrast, model development if dispersedthroughout the research activities of the Water

—-—‘<’ ~fit }kfera[ .$~J~tLL’aTt’ btxchun,qe /%gram-A .hnu[[ .\’tip In lmproutn,q L’om -

puta /’ro~ram .\’harlnq, (;tncral At { (junting (J1’fi( c, January 1978, p. 13.

Resources Division of USGS. A problem-solvingfocus is provided by the USGS Federal-State Co-operative Program, which assists State and localagencies in acquiring needed water resource infor-mation on a case-by-case basis, using analyticalresources throughout the division to develop site-specific models that deal with the particular prob-lem at hand. These two approaches are describedin greater detail below to illustrate the major op-tions available for agencywide coordination of mod-eling activities. In addition, a third organization—the Instream Flow Group of the U.S. Fish andWildlife Service—is presented to illustrate thepotential for advancing model use and modelingcapabilities through innovative interdisciplinary, in-teragency analytical work.

Army Corps of Engineers’ HEC

Established in 1964, HEC provides assistance inapplying state-of-the-art technology (primarilymathematical models) to current hydrological plan-ning, design, and operation problems. WhileHEC’S initial purpose was to provide hydrologicalengineering services to the Corps of Engineers 52offices, it currently supports the development andimplementation of a broad range of water resourceanalysis and planning techniques. Services are pro-vided extensively to non-Corps of Engineers users—private firms; other Federal, State, and local gov-ernment organizations; universities; and foreignorganizations—which currently account for over 80percent of HEC model use.

HEC professionals locate, evaluate, and/or devel-op new procedures and techniques for analyzingwater resources; develop and maintain 12 majorcomputer models; teach currently available tech-niques and model use in formal training courses;and assist Corps of Engineers offices and others inapplying models and techniques to current studies.To provide readily accessible user assistance, HECassigns each of its major models to one or moreengineers, who answer user questions over the tele-phone and handle unforeseen difficulties that mayarise.

HEC has evolved a number of basic guidelinesto ensure the widest possible use for the models itdevelops and/or maintains. Models are designedfor general use, so that most problems in a fieldof interest can be solved with the same model, and



Extensive field investigations, analyses, and publicparticipation are part of the planning process for theArmy Corps of Engineers’ study of the Passaic RiverBasin. HEC provides analytical support for Corps

studies, using a wide variety of modeling andother planning techniques

require little or no program modifications. Com-monly accepted techniques are used where possi-ble, and a variety of approaches is provided withinan overall modeling package to suit individual needsand preferences. All programs are written in a com-monly accepted computer language (FORTRANIV), and are also designed to be easily transport-able to a wide variety of computer types.

The ease with which the model can be used isalso an important design criterion. To documentmodels, HEC develops both user’s and programer’smanuals. The user’s manual is written both to allowthe beginner to use the model easily and to permitexperienced users to employ the model for com-plex problems. The procedures for entering data

into the computer are designed for simplicity, andare thoroughly described in the user’s manual.

HEC distributes copies of its models and docu-mentation without charge to a variety of users;private firms are charged a nominal fee for repro-duction and handling costs. A November 1976 sur-vey showed an annual distribution of approximately

700 model copies, and found that over 2,700 copiesof HEC models were still in use by the offices thatreceived them. HEC also publishes newsletters,professional papers, computer program abstracts,and training course notebooks to promote the useof its models.

Training courses are an integral part of the HECuser assistance program. The center provides 24weeks of training courses annually for Corps ofEngineers staff, reserving approximately 10 per-cent of the space in these courses for non-corps ofEngineers personnel. A number of the HEC-devel-oped courses have also been adopted for use byU.S. and Canadian universities. Fifteen of theHEC courses have been videotaped; tapes and in-structional material are available for loan, and may

be used by visitors to HEC in conjunction withindividualized instruction from center staff. Despitethese efforts, however, HEC staff acknowledge thatinsufficient training is currently available to thenon-Corps of Engineers user.

USGS Water Resources Division

USGS is a service-providing organizationcharged with collecting data on and analyzing theNation’s physical resources. Its Water ResourcesDivision collects long-term multipurpose data onsurface water, ground water, water quality, andwater use; performs special interpretive studies ofthe physical, chemical, and biological characteristicsof water; and conducts appraisals for environmentalimpact evaluation, energy development, coastalzone management, subsurface waste storage, wasteutilization, land-use planning, flood plain manage-ment, and flood warning systems. Water resourcemodels are used in all phases of the divisions activ-ities, and are an integral part of its analytical capa-bilities.

The division undertakes a substantial amount ofdata gathering, resource investigation, and researchfor general use throughout the Federal Govern-

86 Use of Mode/s for Water Resources Management, Planning, and Policy

ment. It also carries out work to meet the analyticalneeds of other Federal agencies on a cost-reimburs-able basis, involving funding tranfers of nearly $30million in fiscal year 1978. Nearly half the division’sbudget, however— $70 million for fiscal year 1978—was involved in activities carried out for the Fed-eral-State Cooperative Program. The program,funded on a 50-50 basis by the division and Stateand local governments, provides data, information,and analyses to over 600 non-Federal agencies, con-centrating on problems whose solutions are ofmutual benefit to Federal, State, and local waterresource professionals and decisionmakers. Morerequests for studies and offers of matching fundsare received by the division each year than can beundertaken under current funding levels; decisionsand negotiations regarding projects are made ona decentralized basis through 47 district offices.Most arrangements for undertaking studies are for-malized with a simple one-page standard coopera-tive agreement.

Research and analytical work for the cooperativeprogram is implemented under USGS direction,principally by Water Resources Division staff.These activities take place primarily at the division’sregional centers in Reston, Va., Lakewood, Colo.,and Menlo Park, Calif.; at the Gulf Coast Hydro-science Center at Bay St. Louis, Miss.; and occa-sionally in other sections of the country as needed.The combination of decentralized planning andcoordinated interdisciplinary analysis at centrallocations allows the program both to be responsiveto real-world problems and indications of emerg-ing priorities, and to pool manpower and exper-tise in the relatively small field of hydrology.

When a model is needed to perform a particularanalysis, USGS professionals develop one to suitthe specific site characteristics under study. Thus,each model developed by the division is an in-dividually tailored, single-use model, though it mayoften be based in part on a previously developedresearch prototype or an earlier modeling effort.Models and model-related activity account for be-tween 10 and 12 percent of the Water ResourcesDivision operating budget—from $12 million to $15million was spent on applying models to specificproblems, and from $3 million to $4 million on re-search, in fiscal year 1979.


USGS investigations of water problems are often coupledwith laboratory resaarch and modeling activities toprovide the information necessary for a thoroughanalysis. Here, a USGS research scientist demonstratescomputer-controlled lab equipment used to make

calculations for the study shown in foreground

One of the keys to the strength of the USGS ef-fort is the reputation for impartiality enjoyed bythe division’s studies. Many of the projects it un-dertakes are associated with controversies amongconflicting interests. Because the division’s analysesare perceived to be relatively free from mission-ori-ented biases, its results tend to be accepted by allparties to interstate, intrastate, State-local, and in-ternational disputes.

USGS also provides extensive hydrological andwater resource-related training. Courses are con-ducted primarily at the USGS National TrainingCenter at Lakewood, Colo., and include a largenumber of sessions on modeling surface water,


ground water, and water quality. Open to person-nel throughout the Federal Government and fromState agencies and international organizations,courses are geared toward various levels of profes-sional expertise, some of them designed for admin-istrators, others for technicians and resource special-ists. Nationally and often internationally recognizedscientists and engineers from the Water ResourcesDivision serve as the main instructional staff fortraining sessions. Experts from other divisions ofUSGS, other Government agencies, universities,and private industry also serve as lecturers andspecial consultants.

Cooperative Instream Flow Service Group

The extensive development of water resourcesin the Western United States over the past 15 yearshas had major effects on the availability of waterfor instream uses such as recreation, and fish andwildlife needs. During this period, concern overrapid decreases in instream water availability cre-ated broad-based expressions of need for a compre-hensive source of information and expertise onstandard tools for analyzing instream water needs.Such concern reached major proportions by themid- 1970’s— particularly in the Pacific Northwest,where protection of the anadromous fish resourcehas been an acute problem for many years.

During the early 1970’s, a number of entities en-gaged in analyzing instream flow problems bothfrom a technical and legal/institutional perspective.The general response of natural resource manage-ment agencies, and the U.S. Fish and Wildlife Serv-ice in particular, was to organize groups of fisheriesor wildlife biologists to make suggestions to thewater management community. This approachproved relatively unsuccessful, as resource manag-ers were not inclined to give strong credence to asolely ‘ ‘biological’ perspective. As an alternative,the Office of Biological Services within the Fish andWildlife Service proposed to develop an inter-disciplinary, service-oriented center for instreamflow analysis, drawing personnel from numerousFederal and State Government agencies. Fundingto create this center— the Cooperative InstreamFlow Service Group—was eventually providedthrough EPA for fiscal years 1976 through 1979.Funding is currently provided directly by DOI.

Potential users of Instream Flow Group (IFG)services identified two major needs: 1) informationon biological and hydrological aspects of instreamuses; and 2) information on institutional means cur-rently (or potentially) available for ensuring ade-quate stream flows. Satisfying these needs requiredthe creation of a team of personnel encompassingthe biological, physical, and social sciences togather, collate, and disseminate information on in-stream uses. Model developers and users were alsoconsidered a necessary part of the team effort, inorder to create usable mathematical tools for in-stream analysis. Staffing for IFG was accomplishedthrough the Fish and Wildlife Service, State agen-cy personnel recruited under the IntergovernmentalPersonnel Act, and detailees from other Federalagencies.

Since its inception, the group has concentratedon transferring information on instream uses viacomputerized data retrieval systems, library func-tions, preparing information papers, training, andproviding technical assistance on various aspectsof stream flow protection. Two of its major analyti-cal efforts have been in developing methods to:1) analyze the effects of incremental changes in flowon instream uses such as fish and wildlife habitat;and 2) analyze tradeoffs between instream and off-stream uses as part of regional water assessments.

In the first area, IFG has developed the instreamflow incremental methodology, an analytic ap-proach to evaluating changes in the fish-carryingcapacity of stream reaches. This methodology hasbeen widely adopted for use in Western and Mid-western States. For the second area, work is in prog-ress for a regional reconnaissance method to evalu-ate general stream characteristics within a waterbasin. Using the Upper Colorado River Basin asa case example, the group is attempting to developa unified basin modeling approach as a decision-making tool to determine the cumulative effects ofvarious water management schemes.

The group provides two types of assistance to im-prove the level of competency among users of itscomputer-based models. First, it offers an array oftraining opportunities designed to inform participantsabout the basic issues, develop an overview under-standing of solutions to the problem, and finally,


provide instruction in using computer-basedmodels. The group maintains an extensive train-ing program throughout the Western United Stateson such subjects as western water law, strategiesfor protecting instream flows, and negotiating in-stream flows. In addition, the group offers train-ing in the use of modeling technologies. For exam-ple, its instream flow field techniques short courseand its computer analysis short course are designedto give the user the technical competence requiredto conduct analyses of instream flow requirements.

Second, IFG provides technical assistance. This en-tails helping users who are engaged in instream flowanalysis to develop study plans, make measure-ments, analyze data, develop and present recom-mendations, and implement them. Technical as-sistance also involves assisting State and Federalwater administrators in determining areas and op-portunities for factoring instream uses into Statewater plans or land management plans.

IFG officials attribute the group’s success to itsstrong interdisciplinary focus, the quality of its per-sonnel, clear identification of the problems to beaddressed, and frequent interaction among staffmembers and group leaders. The communicationengendered among professionals in a number ofdisciplines is considered a vital prerequisite to devis-ing methodologies, solutions, and recommendationscredible to the wide range of interests that are partyto water resource management decisions.

Agency-Level Mechanisms forProviding Information on and

Access to Existing Models

A number of mechanisms are currently used invarious Federal agencies for making model-relatedinformation available to users. Such services mayrange from simple directories of available models;to user support groups for transferring modelingtechnologies; to clearinghouses that match userneeds to available models, test and evaluate model-ing systems, and provide user training. Four majoragency efforts are described below: 1 ) the Interna-tional Clearinghouse for Groundwater Models(ICGWM); 2) the EPA Stormwater ManagementModel (SWMM) User’s Group; 3) the EPA Cen-ter for Water Quality Modeling; and 4) the USDALand and Water Resources and Economic Model-

ing System (LAWREMS). Each represents a sub-stantially different approach to managing model-related information and improving user access toexisting modeling systems, and addresses differentkinds of user needs.

International Clearinghousefor Groundwater Models

Studies begun in 1975 at the Holcomb ResearchInstitute indicated that, while significant progresshad been made in developing and using numericalmodels for ground water-related resource manage-ment, major gaps existed between the need for andthe existence and actual application of ground watermodels. Access to existing models, and identifyingmodels designed for specific applications, wereobserved to be serious problems. The gulf betweenmodel developers and model users needed to beclosed by developing mechanisms for transferringmodeling technology from experienced modelers toothers needing these important analytical tools.

Further research work, funded by EPA and theScientific Committee on Problems of the Environ-ment, developed guidelines for establishing a clear-inghouse to assist users of ground water models,and an outline of the primary objectives and serv-ices of such a center. ICGWM became operationalwhen EPA funded a 3-year project to staff and fulfillthe clearinghouse objectives at the Holcomb Re-search Institute. The project is intended to test theutility of the clearinghouse approach to technologytransfer using ground water models as an example.

The clearinghouse concept is based on the ideathat a central information source can greatly reducethe effort normally required to acquire model in-formation. Through the clearinghouse, the poten-tial user can be exposed to all levels of availabletechnologies and can expeditiously determine whichis most appropriate for his purposes. Further, aclearinghouse provides a natural setting for testingand evaluating models, and for education in modelapplications, operations, and theory for nontech-nical and technically trained personnel alike.

The first major activity of ICGWM was to devel-op a ground water model information search andretrieval system. A model annotation form—a de-tailed checklist containing both general and specificmodel characteristics—was circulated international-

Ch. 4—Federal Use and Support of Water Resource Models . 89

ly to known model developers, with a request tocomplete the form by checking off those characteris-tics that apply to their models. These forms wereused to develop a computer-assisted Model Annota-tion Retrieval System (MARS). As of February1982, MARS had over 400 unique model annota-tions— and their number is constantly growing.

To access information, the same model annota-tion form is distributed to interested model users.The user checks off the desired model characteristicsand returns the form to the clearinghouse, whereMARS compares it to the stored models and iden-tifies those that meet all or most of the desiredcharacteristics. This retrieval system is designed toavoid the complexities that plague traditionalsystems controlled by key words. Its success canbe gaged by the fact that user requests for modelinformation grew from an average of 6 per weekduring the first 6 months of operation to 85 perweek as of April 1980.

Moreover, developers have begun to recognizethe commercial value of having their models in-cluded in MARS. Evidence of competition hasrecently been observed among developers to ensurethat their works are available to potential usersthrough the clearinghouse.

The second phase of development at the clearing-house involves the acquisition, evaluation, and rec-ommendation of available models. ICGWM is cur-rently assembling a selection of functional modelsthat: 1) are available; 2) have been tailored to cur-rent key ground water problems; and 3) have beentested for accuracy, usability, and transferability.A screening process is being developed to examinemodels for validation and performance, and to cre-ate documentation guidelines for model software.In the process, close attention will be given to themodel user’s manual compiled by the model devel-oper.

The other major activity started during the sec-ond phase of development is a series of workshopson ground water modeling. The workshops, heldannually at the Holcomb Research Institute, arestructured in a stepwise fashion, beginning with ageneral introduction to the applications and limita-tions of models for policy makers and decision-makers, and progressing toward advanced mathe-matical theory in later workshops. The last three

sessions are ‘‘hands-on’ experiences where the at-tendees vigorously work with computer models anddevelopers. The first series of workshops was con-ducted with an enrollment of 140; indications arethat the workshops have been highly successful ineducating water resources professionals about thepotential of models. Future plans call for presentingthe general session at regular time intervals atregional centers throughout the United States, andthe entire workshop series at various internationallocations.

The third phase of development calls for estab-lishing formal international linkages to the center,and developing financial support to continue theexpansion of the clearinghouse. To the latter end,ICGWM plans to undertake technology transferactivities to assist users, operating under an estab-lished fee structure for technical consulting work.However, charges for these services, the workshops,and the use of MARS are unlikely to cover the costof daily operations—outside sources of funding willneed to be secured to support clearinghouse ac-tivities. ICGWM officials suggest that an appraisalof the cost effectiveness of the center will only bepossible once all of its major activities are fully

operational. Over time, however, as demands forservices grow, the clearinghouse is likely to requireless financial assistance from outside sources.

ICGWM officials consider that the clearinghousehas been successful thus far in making ground watermodeling information accessible, in reducing thetime and effort required for model users to acquireappropriate modeling tools, and in educating inter-ested professionals about the benefits and limita-tions of models. The clearinghouse approach alsoappears to hold major potential as an effective medi-um through which new technologies can be trans-ferred.

SWMM User’s Group

EPA’s SWMM is one of the largest and mostcomprehensive mathematical models for simulating

storm and combined sewer systems, their associatedstorage and treatment facilities, and their impactson receiving waters. Its reliability and widespreadavailability have made SWMM the most widelyused model of its type in the United States andCanada, and have been important in increasing the

90 ● Use of Models for water Resources Management, Planning, and Policy

use of models by engineers and planners. TheSWMM User’s Group has been instrumental inachieving the widespread dissemination and accept-ance enjoyed by this important modeling tool.

Initially developed in the early 1970’s, SWMMis a complex, computer-based model that simulatesthe movement of stormwater through a watershed,determines quantity and quality of runoff, routesthis runoff through a combined (or separate) sewersystem with specified storage and treatment facilitiesand operating policies, and thence into receivingwaters, where resulting water quality is quantified.SWMM is modular, having five computationalblocks—each of which can be used alone or withother blocks.

When the model first became operational, EPA’sOffice of Research and Development (ORD),which sponsored the development of SWMM, de-cided to organize an informal user’s group as itsprincipal means of technology transfer. ORD rec-ognized that the model’s principal users would notbe EPA staff, but rather the members of the consult-ing engineering profession, acting on behalf ofEPA, or of State, regional, or local governments,or industrial and commercial clients. These model‘‘clients, who are normally free to select the mod-els to be used, generally base their decision on amodel’s ease of use, cost effectiveness, and reliabil-ity.

To assure that SWMM would be readily usable,ORD devoted substantial attention and resources

Photo credit: @ Ted Spiegel, 19s2

Modern urban development has substantially increased both the complexity of urban runoff management and the needfor adequate sewer transport, storage, and treatment of runoff. The Albany, N. Y., skyline provides a dramaticdemonstration of the interactions between built-up urban areas and natural water bodies. Models such as EPA’sSWMM can be used to assess the impact of Albany’s runoff on flows and water quality levels in the Hudson River


to documenting and testing the model before at-tempting to disseminate it. All or parts of SWMMwere tested in five different locations, and the resultsof the tests included in the original documentation.This, in the judgment of the SWMM developers,was the single most important factor in gaining ac-ceptance for the model.

The first step in creating a technology transferprogram for SWMM was to set up a mechanismfor distributing the model and its documentation.Working from a small list of interested people,ORD offered to duplicate the model and documen-tation for anyone who sent in a blank tape. Since1972, over 300 users have received copies of theprogram, and perhaps 1,000 copies of the documen-tation have been sent out. Test data are furnishedwith the program to allow each recipient to checkthat the model is operating correctly.

User’s Group meetings were seen as the bestmechanism for transferring knowledge among expe-rienced model users and those who were new toSWMM. The meeting approach combines instan-taneous communication of current knowledge withclose interpersonal association and support formodel users.

About 20 individuals attended the first SWMMUser’s Group meeting in early 1973. Since thattime, meetings have been held on a semiannualbasis, and the group membership has grown to al-most 500, including representatives from 19 foreigncountries. An informal user’s bulletin, first pub-lished in 1973, has been sent out periodically, toannounce meetings or other items of interest.

User’s Group meetings are colloquial and infor-mal in atmosphere, in order to allow a high degreeof interaction between individuals with common in-terests and problems. To encourage group mem-bers to examine other models that may be madeapplicable to their problems, at least one presenta-tion per meeting focuses on the use of a differentwater quality model. Since 1977, formal User’sGroup proceedings have been published to recordmeeting activities.

To maintain and update SWMM, ORD decidedon the services of an outside contractor, rather thanattempting to use in-house resources. The decisionwas based in part on the perception that in-house

efforts tend to become self-perpetuating and to stiflecreative change. In addition, the group that main-tains the model is available to users for over-the-telephone questioning or detailed consulting on anormal fee basis. This supplements the informalfree advising network among users, and the avail-ability of User’s Group members to consult on afee basis when needed. EPA has resisted requeststo make minor changes in the program. Three up-dated versions of the model have appeared sincethe original; users are encouraged to make otherlocal changes that they desire.

Initially, training in the use of the model wassponsored by EPA; since 1976, however, the only

available formal training has been offered private-ly by various universities. The agency’s experiencehas been that, given the support of the User’sGroup, model users are generally willing to trainthemselves. In this sense, the User’s Group hasevolved into an inexpensive alternative to agency-sponsored training programs.

Costs associated with the SWMM User’s Grouphave been relatively low. The group requires about20 percent of the time of one professional, about10 percent of one secretary’s time, and about$5,000 per year to cover printing costs for meetingproceedings. Other costs include mailing, newslet-ter printing, maintaining the User’s Group list ona time-sharing computer, and duplicating theSWMM program—all of which consume perhaps$2,000 to $3,000 per year at most. Meeting costsare minimal-since no travel expenses or honorariaare paid to speakers—and are covered entirely byregistration fees.

EPA Center for Water Quality Modeling

ORD established the Center for Water QualityModeling in 1980 to distribute, maintain, and pro-vide technical assistance in the use of selected EPA-developed water quality models. The center, locatedat the Environmental Research Laboratory inAthens, Ga., serves as a focal point for assisting

users in locating and applying models developedby EPA operating and research programs.

EPA’s use of water quality models increased rap-idly in the 1970’s. Separate model development ac-tivities within individual EPA offices resulted in a

—

92 . Use of Mode/s for water Resources Management, P/arming, and policy—

proliferation of seemingly different models, al-though many models were actually modificationsand/or extensions of earlier modeling attempts. Thelack of a central reference point for model use withinthe agency impeded the correction of initial model-ing errors, so that errors tended to be propagatedin successive modeling activities. Additional impe-tus for creating an office to support and maintainfrequently used models came from the growingneed to provide expert technical/analytical assist-ance to States and EPA regional offices. The suc-cess of EPA’s own SWMM User’s Group and theCorps of Engineers’ HEC in encouraging wide-spread model use and acceptance pointed to thelarge potential benefits to be derived from such anoffice.

The center’s initial support role has been limitedto four widely used modeling packages: 1) QUAL-11 (a stream water quality model); 2) SWMM/RECEIV (an urban runoff model); 3) ARM (anagricultural runoff management model) and NPS(a general nonpoint source runoff model); and4) HSPF (a multipurpose hydrologic simulationprogram). Center staff provide copies of modeldocumentation and tapes of the models’ computercodes to interested users, and relay informationabout errors or other problems back to the models’developers. Center personnel are currentlyevaluating a number of models for possible addi-tion to the four packages presently being supported,and are developing a quantitative r-node] selectionprocedure to assist users.

A number of older EPA models are also on fileat the center; however, current manpower limita-tions do not permit them to be supported or main-tained. Computer programs, manuals, reports,etc., for these models are distributed on request ona ‘ ‘use at your own risk’ basis. While the centerroutinely receives requests for models in this cate-gory, it has not checked, corrected or updated them,and functions primarily as an archive in this area.

For its supported model packages, the center as-sists users by sponsoring intensive ‘ ‘hands-on’workshops and technical seminars, taught by ex-perts from the Environmental Research Laboratoryand representatives of the organizations that devel-oped the model under EPA grants or contracts,Workshops are open to all model users, and the

level of user interest dictates the number of work-shops presented. For fiscal year 1980, several work-shops were held on the HSPF; two sessions wereheld on QUAL-11. A newsletter for informing usersof training opportunities, advising them of model-ing errors or updates, and quickly providing addi-tional model-related information was introduced inSeptember 1980. Superseding and expanding onthe SWMM User’s Group Newsletter, the newpublication has used the audience established byits predecessor as a base for informing users of thecenter’s existence and activities. Current adminis-tration policy, however, prohibits the center frompublishing the newsletter.

At present, the center’s manpower resources arevery limited; consequently, it does not offer routine‘‘online’ technical assistance to all model users.While limited technical assistance is available onspecific agency problems, and can be providedthrough procedures established prior to the center’sinception, even such requests are generally discour-aged. To expand the availability of technical assist-ance in running models, the center concentrates ondeveloping user interaction activities, based on theuser group concept, in order to teach users to solvetheir own problems. Such an approach has in thepast proved highly successful in encouraging theuse of standardized, widely applicable models.However, inclusion of additional, more specializedmodels in the center’s support role would likely callfor the provision of greater levels of technicalassistance by center staff.

USDA Land and Water Resources andEconomic Modeling System (LAWREMS)

A December 1976 request from the Senate Com-mittee on Agriculture, Nutrition, and Forestry forUSDA assistance in evaluating the department’sland and water conservation programs provided theinitial impetus for the creation of LAWREMS. Asa followup to its report to the Senate, the USDALand and Water Conservation Task Force createda modeling team composed of representatives frommajor USDA agencies, giving it the responsibilityto develop an information system about currentdata and analytical capabilities within the depart-ment, and to outline future goals and directions forintegrated departmentwide modeling systems.


The LAWREMS team developed a computer-ized directory of data sets and models related towater and land resource analysis, relying primar-ily on those created by various USDA agencies. Theteam also established a file of related documenta-tion and reports, arranged for ongoing computerassistance to facilitate access to and transfer of dataand models, and created a small staff to maintainthe directory and provide limited technical assist-ance to users.

The initial LAWREMS directory contained ap-proximately 300 descriptions of models and datasets, each of which included such information astitle, agency, an abstract, purpose, keywords, geo-graphic coverage, operational status, name and ad-dress of technical contact, and basic technical in-formation. The directory is currently housed withinthe Resource Systems Program of the EconomicResearch Service.

While LAWREMS support services include di-rect access to a limited number of models and datasets within USDA, its primary function is to directusers to the individuals or organizations that havedeveloped these tools. The system is intended to

improve communication among program analystsand researchers about existing data and models,their use, limitations, and linkages. The existenceof such a system is also intended to encourage theupkeep, maintenance, and use of existing data filesand models. Services are provided primarily toUSDA analysts working in the area of resource con-servation; however, expanding access to includeother USDA personnel, as well as interagency andnon-Federal use, has been envisioned as part offuture LAWREMS activities.

LAWREMS support staff are responsible formaintaining and updating the directory, and pro-vide some technical assistance to USDA land andwater conservation program evaluators and ana-lysts. Provision of “hands-on” training to a limitedcategory of users on selected data and analytic Sys-tems is contemplated as part of ongoing staff activ-ities. Staff would also provide assistance in coordi-nating agency efforts to design new models or mod-ify existing ones, along with identifying data re-quirements, when information is not available oraccessible from existing sources.

Chapter 5

Use of Models by State Governments

Contents

Summary of Survey Results . . . . . . . . . .*. *. * * 0 . . * . * * * * * + . * * * * *.****.*.

Procedure Used in Conducting the OTA State Modeling Survey . . . . . . . . . .

Trends in Current and Potential State Model Use . . . . . . . . . . . . . . . . . . . . . .

Constraints to Model Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Developing Models To Meet State Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Data Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Lack of Qualified Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Access to Federal Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Reliability and Credibility of Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Model Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Model Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

State Model Use in Individual Water Resource Issues . . . . . . . . . . . . . . . . . . .Surface Water Flow and Supply Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Surface Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ground Water Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Economic and Social Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page97

98

98

1 0 4104105105106106107107107107

108108110113114

TABLES

Table No. Page

5. Number of States Indicating Existing or Potential Model Use . . . . . . . . . . . . . 996. Rankings of State Model Use for All Water Resource Issues . . . . . . . . . . . . . . 101

FIGURES

Figure No. Page

7. Number of Water Resource Issues for Which States Indicated Current orPotential Model Use.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

8. Surface Water Flow and Supply Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1019. Surface Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10. Ground Water Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10311. Economic and Social Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Chapter 5

Use of Models by State Governments

State governments have extensive water manage-ment responsibilities, ranging from flood controlto prevention of ground water contamination tocomprehensive river basin management. These re-sponsibilities have increased in recent years, duein part to Federal environmental legislation thatrelies on Federal-State partnerships to address awide variety of national water resource problems.The Clean Water Act, the Resource Conservationand Recovery Act, the Water Resources PlanningAct of 1965, and the Safe Drinking Water Act, inparticular, assign States numerous additionalobligations requiring high levels of technical exper-tise and highly sophisticated planning and manage-ment decisions.

Computer models can significantly aid States inundertaking these added responsibilities. While sev-eral States have sophisticated modeling capabilities,many State officials acknowledge that the use and

understanding of models by State agencies is farbelow the level it should be. To gain a better under-standing of factors affecting model use at the Statelevel, OTA surveyed professional-level personnelat water resource agencies in all 50 States. Thischapter reports the results of that survey, includingthe kinds of models used, the extent of their use,and the problems encountered by State water re-source professionals. It contains:

summary of survey results;procedure used for conducting the OTA Statemodeling survey;trends in current and potential State modeluse;major constraints to model use identified byState personnel; andState model use in individual water resourceissue areas.

SUMMARY OF SURVEY RESULTS

State water resource professionals generally usecomputer models developed by others—particularlyFederal agencies. The size, budget, and technicalcapabilities of most State water resource agenciesdo not permit them to develop models; consequent-ly, State model use depends on having access tofederally developed models and on the availabilityof federally sponsored training and technical assist-ance.

In many States, model use is primarily restrictedto a few well-established, widely available models.State personnel are often poorly informed about theavailability of models and data, and about technicalassistance available to facilitate model use.

Data inadequacy was the most frequently citedconstraint to effective State model use. While most

State officials indicated that increased Federal fund-ing for data collection would improve State mociel-ing efforts, they also emphasized the importanceof improving access to Federal (and other State)data bases.

Low salary levels and high turnover rates werealso stressed as hindrances to States’ efforts to main-tain staffs with expertise in modeling. After dataneeds, States placed highest priority on increasedfederally sponsored training in model use and appli-cations for both technical and managerial person-nel. other major State concerns included the needfor Federal sponsorship of simpler models for State-level use, and improving the reliability and credibil-ity of models through Federal coordination, clear-inghouse activities, and standard-setting.

97


PROCEDURE USED IN CONDUCTINGTHE OTA STATE MODELING SURVEY

OTA surveyed State agencies responsible for thesupply and quality of freshwater resources in June1980 to determine the extent of their current andpotential water resource model use. State person-nel were asked to identify major problems facingthe States in using models and Federal policy op-tions to improve State model use.

The survey was divided into two major sections.The first assessed existing and potential State modeluse in four major water resource areas: 1 ) surfacewater flow and supply; 2) surface water quality;3) ground water; and 4) economic and social con-cerns. These areas were further divided into a totalof 33 water resource issues. * Model use for eachof these issues was assessed for three different deci-sionmaking functions: 1 ) operations and manage-ment; 2) planning and policy; and 3) other (pri-marily research). The respondents were also en-couraged to provide additional information on therole of models for each of the 33 water resourceissues—e. g., the specific regulations for which themodel is applied. Detailed results of this portionof the survey are compiled in appendix E.

The second section of the survey posed threebroad questions on State model use:

1. Identify the most important needs associatedwith water resource model development inyour State, and suggest options available tothe Federal Government to assist your State.

*A discussion of the modeling tc( hniqucs used to analyze each ofthr fbur major rcsoutx c areas, and a review of the prohlcrns and mmlcl-ing ( apahil I t ics MS(X iatcd w lth [’w h of t h[’ 33 water r{’sour( c. issues,is prc’scntcd in ( h, 6

2.

3.

Identify the most important problems andneeds associated with water resource modelmaintenance in your State, and suggest op-tions available to the Federal Government toassist your State.Summarize reasons models are or are not usedby your State. Consider the reliability andcredibility of models, and human/institutionalproblems. Suggest options available to theFederal Government to assist your State inmodel use.

Surveys were sent to State agencies responsiblefor both water quality and water supply concernsin each State. Since these responsibilities often restwith different State agencies, surveys were sent todifferent agency contacts for water supply and waterquality issues. Names of key agency contacts weresuggested by the State water resources researchinstitutes.

Six surveys were sent to each State agency con-tact (two contacts from each State)—a total of612surveys. Each contact was asked to circulate thesesurveys among the agency personnel familiar withthe use of models in the State for the 33 listed waterresource issues. Most of the surveys returned weresubmitted independently by individual agency per-sonnel; some of the States, however, returned a sin-gle response that had been circulated throughoutthe agency.

All 50 States and the District of Columbia re-turned completed surveys. However, the numberof surveys returned from each State varied fromone to six. A total of 103 surveys were returned.

TRENDS IN CURRENT AND POTENTIALSTATE MODEL USE

Forty-eight States currently use water resource use only a few of the many models available—pri-models. Collectively, the States employ these mod- marily those based on well-established modelingels to address problems for all 33 identified water techniques like wasteload allocation or ground waterresource issues. However, it is clear that most States supply models.

Ch. 5—Use of Models by State Governments ● 99

The majority of States use models for less than10 resource issues, and 14 States (28 percent) usethem for five or fewer resource issues. Only one-fifth of the States use models for more than 15issues (see table 5 and fig. 7).

In contrast to their current model use, a majorityof the States identified potential uses for models inmore than 20 of the 33 water resource issues. Nearlyone-fourth of the States indicated that they coulduse models for over 30 issues. These statistics indi-cate that although models are currently used fora limited range of issues, State offcials see increasedmodel use as important for expanding State rolesin water resources management, planning, and pol-icy (see fig. 7).

Large discrepancies between existing and poten-tial model use can be highlighted by ranking eachof the 33 resource issues according to the percent-age of States indicating current or potential modeluse. * Table 6 lists the States’ top 10 existing andpotential water resource modeling uses, and figures8-11 illustrate the percentages of States indicatingcurrent and potential use of models for each of the33 water resource issues.

These data indicate several trends: surface waterflow models are currently the most widely used—5of the 10 top-ranked resource issues are surfacewater flow issues. For ground water issues as well,supply and flow models rather than quality modelsreceive the greatest amounts of current use. Threeof the top 10 issues, however, are surface water

*These rankings are obtained for each resource issue by totalingthe percentage of States using models to address that issue over thethree specified decisionmaking functions (operations and management,planning and policy, and research). This combined number betterreflects model use for each issue than percentages reported for anyone decisionmaking category. A State may use sei’eral different modelsfor the same issue—one for planning and policy, one for operationsand management, and another for research.

Table 5.—Number of States IndicatingExisting or Potential Model Use

Number of issues Existing Potential

0 through 5. . . . . . . . . . . . 14 26 through 10. . . . . . . . . . . . 14

11 through 15. . . . . . . . . . . . 12 816 through 20. . . . . . . . . . . . 5 721 through 25. . . . . . . . . . . . 3 926 through 30. . . . . . . . . . . . 2 831 through 33. . . . . . . . . . . . 0 12SOURCE: Office of Technology Assessment,

quality issues. One of them, wasteload allocation,is the issue for which the greatest number of Statesindicated current or potential model use. Whilemost States do not often employ models to assesswater quality problems, the few problems that havebeen studied most—e. g., wasteload allocation anderosion/sedimentat ion— are widely analyzed usingmodels. States tend to be frequent users of flow andsupply models, in part because Federal agencieshave been active in developing and applying them.The Corps of Engineers and the U.S. GeologicalSurvey (USGS) actively assist States in modelingefforts for flood forecasting and control, droughtand low-flow forecasting, streamflow regulation,domestic water supply, ground water supplies and

Photo credit: Environmental Protection Agency

Water quality concerns, and the models used to analyzethem, are increasingly important to State agencies. Whileonly 3 of the States’ 10 most important model use areasare currently water quality issues, OTA’S survey of Stateofficials shows that 7 of the 10 top water modeling areas

are expected to involve water quality in the future

100 . Use of Mode/s for Water Resources Management, Planning, and policy

Figure 7.—Number of Water Resource Issues for Which States Indicated Current or Potential Model Use

5 10 15 20 25 30 35 5 10 15 20 25 30 35 5 10 15 20 25 30 351

Ala.

oAlas.

21La.

Me.

Ark.

Calif.

Colo.

Corm.

Del.

D.C.

Fla.

Ga.

Hi.

Ido.

Ill.

Ind.

Iowa

Kans

Mass.

3

0

28

Md.

Mich.

1Minn.

Miss.

Mo.

Mont.

Nebr.

Nev.33

N.H.

N.J.

N.Mex

N.Y,

N.C.

Okla.29 31

Pa.

R.1.

32S.c.

S.Dak.32

Term.33

Tex.

15Utah

14

P 5Va.

o

33

Wyo.33

33

29

The number of water resource issues for which States currently use models.

The number of water resource issues for which States could potentially use models.

SOURCE: Office of Technology Assessment.

Ch. 5—Use of Models by State Governments 101

Table 6.—Rankings of State Model Use for Ail Water Resource issues (top ten)

Existing Potential● Wasteload allocation ● Wasteload allocation● Ground water supplies and safe yields ● Conjunctive use● Streamflow regulation . Drought and low-flow forecasting● Drought and low-flow forecasting ● Impacts on aquatic life● Flood forecasting and control

{ ● Ground water supplies

● Conjunctive use ● Waste disposal—ground water● Impacts on aquatic life ● Agricultural pollution—ground water● Erosion/sedimentation . Urban runoff● Domestic water supply ● Erosion/sedimentation. Instream flow ● Accidental contamination of ground water

aTied for fifth place


Figure 8.—Surface Water Fiow and Suppiy issues

Percent

100

80

Operat ions and 60management

40

20

0

67 67

5143 43

23

f “>.

63 63 6160 -

61

Planning and57 55

45policy 40

20 -

0

100r

Other60

40 t 3520 22

20 ‘ 6

oFlood Drought Streamflow Instream Domestic Irrigated Off stream Water use

forecasting ancf low regulation flow water agriculture use efficiencyflows supply

Percent of States currentlyusing models

Percent of States indicating potential model use



Figure 9.—Surface Water Quaiity issues

Percent100r60 -

67 69Operations ~ - 55and 55management

40 -27

100rfan L

100 r60

tOther 60

t40 -

25 23 22 27 25

(lSurface Urban Erosion- Salinlty Agricultural Airborne Wasteload Thermal Toxic Drinkingwater runoff sediment runoff allocation pollution materials water

quality quality

m Percent of States currentlyusing models


SOURCE: Off Ice of Technology Assessment.

safe yields, and conjunctive use of ground and sur-face waters.

The characteristics of the top 10 resource issuesfor potential model use differ significantly fromthose with the highest current use. Instead of flowand supply, most of the identified problems involveground and surface water quality concerns—7 outof 10 are quality issues. Ground water issues alsostand out among potential model uses; States rankfive of the six specified ground water resource issuesin the top 10.

One reason for the widespread potential reportedfor surface water quality models is the extensive

responsibilities that States have acquired for meet-ing national clean water goals. Models have an im-portant role in States’ compliance with numeroussections of the Clean Water Act.

Many States stress the need for ground watermodels because modeling techniques are often theonly method of determining the characteristics ofmajor aquifers. However, the lack of ground waterdata—particularly for pollutant transport withinaquifers— severely limits the current use of thesemodels. In general, deficiencies in data and lackof knowledge of physical processes are more seriousconstraints to the use of ground and surface waterquality models than for flow and quantity models.

Ch. 5—Use of Models by State Governments ● 103

Figure IO.- Ground Water Issues

63 61 6160 - 53

57 57Operations andm a n a g e m e n t d .

20 -

0100 r60 - 73

67 71 71

59Planning and 60policy

40 -

20 -

0100 r

Other40 -

25

0Ground Conjunctive Accidental Agricultural Waste Saltwater

water use contami- pollution of disposal Intrusionsupply nation ground

water

mPercent of States currentlyusing models

_ P e r c e n t of States indicating potential model use


Photo credit: @ Ted Spiegei, 1982

Large discrepancies between current and poten-tial use for particular issues suggest that State-1evelmodel use is limited by some technical or institu-tional factor (inadequate data, lack of qualified per-sonnel, poor reliability of the model itself, etc.). Forexample, 34 percent of the States currently usedrought and low-flow forecasting models for opera-tions and management, while 67 percent of theStates indicate potential uses for them. Resourceissue-specific assessments of the States’ current andpotential model use appear in the section of thischapter entitled: “State Model Use in IndividualWater Resource Issue Areas.

State and local water quality agencies have majorresponsibility for designing community wastewatertreatment facilities to meet Federal requirements underthe Clean Water Act. Much of the current use ofmodels—and the perceived need for additional modeling

capabilities—at the State level stems fromFederal requirements for State action


Figure 11 .—Economic and Social Issues

Percent

Operations and G.management t

4140 - 35

27 25 2520 - 8

100r

80 -

Planning and 60 - 59policy

40 -

20 - 14

100 r80

tOther 60

t4o1-

2020 - 10 12

2

0Water costs of cost/ DeveIop- Forecasting Social Risk/ Competitive Unifiedpricing pollution benefit ment use implications benefit water use river basin

control implications management

mPercent of States currentlyusing models



CONSTRAINTS TO MODEL USE

State agencies were asked to identify problemsand needs associated with model development, use,and maintenance in their States, and to recommendways to solve problems and meet State needs. Theresponses to these questions ranged from generalcomments, like ‘‘inadequate data’ or ‘‘lack of qual-ified personnel, to very detailed descriptions ofproblems with specific models or programs. Thefollowing sections highlight trends encountered inthe responses, according to nine subject areas:1) developing models to meet State needs; 2) data

limitations; 3) lack of qualified personnel; 4) ac-

cess to Federal models; 5) reliability and credibilityof models; 6) model standardization; 7) funding;8) maintenance; and 9) documentation.

Developing Models To MeetState Needs

Respondents frequently recommended that Fed-eral agencies develop models to meet State needs.Many of the respondents identified a need for sim-


ple models. Comprehensive models with large datarequirements are of little use to States lacking thetime, resources, or capability to operate them.

According to the survey, many models cannotbe applied to local site-specific problems. Modelsare often designed to simulate an area too large forState purposes.

Data Limitations

The inadequacy of data was the most common-ly identified factor inhibiting State modeling efforts.Not only does insufficient data constrain the devel-opment and application of models, but the use ofunreliable data can produce inaccurate results. Forexample, one respondent commented on the im-pact of using unreliable data for planning advancedwaste treatment plants (AWT):

Millions of dollars have been expended for AWTbased on models which had an inadequate database and the resulting treatment levels requiredmay or may not have been beneficial comparedto the costs.

Many of the respondents noted that the reliabilityand credibility of models is only as good as the in-put data.

The majority of comments concerning data weregeneral, often simply citing ‘‘insufficient data’ or“lack of data. The specific responses, however,fall into several categories:

●

●

●

●

lack of data for specific stages of modeling (i.e.,development, calibration, verification, etc.);lack of data for specific issues (i. e., groundwater supply, nonpoint source pollution);outdated and poorly maintained data bases;andunreliable or inaccurate data (e. g., data sam-pled at the wrong time).

Although the States rely on Federal agencies tosupply a substantial part of the needed data, theyare and expect to be taking the major responsibil-ity for data collection. The major obstacle in meet-ing the States’ data needs is insufficient funding.Along with funding problems, a shortage of man-power was another frequently mentioned factor lim-iting data collection.

Several respondents suggested that a central, orpossibly a ‘‘national’ data bank was necessary.

The States also identified four other important,though less frequently cited, data problems:

●

●

●

●

poor access to Federal/State data banks;no data processing (storage and retrieval) capa-bility;duplication of State and Federal data collec-tion efforts; andintensive data requirements of many models.

Lack of Qualified Personnel

The States have a severe shortage of personnelqualified to develop, use, or maintain models. Thislimits State modeling efforts in many ways. Forexample, some States are unable to modify existing

Federal models to suit their specific needs. OtherStates report that their lack of modeling expertisecauses an overreliance on contractors to develop

and apply models.

Part of the problem is due to the prevailing salary

scales for State employees, which make it difficultto attract and retain qualified personnel. However,most States did not propose supplemental Federalfunding, but strongly recommended increased tech-nical assistance and training by Federal agencies.

One respondent wrote the following about theneed for training in his State:

The main problem of model implementation inIndiana is training. The Federal Governmentshould provide the States with low-cost, applica-tion-oriented training opportunities . . . .

Training was considered a high priority by the re-spondents, second only to data needs. Specific con-cerns about training fell under three categories:

●

●

●

general education for management-level deci-sionmakers to understand and appreciatemodels;advanced training for technical personnel todevelop, use and maintain models; andrecommendations for specific courses, e.g. ,training to use the Environmental) ProtectionAgency’s (EPA) Stormwater ManagementModel.


Although a few States requested funding fortraining, the majority of the States currently relyon federally conducted training programs. Theworkshops and seminars held by the Corps of Engi-neers’ Hydrologic Engineering Center (HEC) andUSGS were praised by many respondents. One re-spondent said:

There is only a handful of people in this State,including the USGS, who can use this type ofmodel (2 D—ground water flow model). The train-ing courses in Denver (sponsored by USGS) havebeen invaluable to us.

The States identified a need for technical assist-ance at all stages of the modeling effort, from devel-opment to maintenance, throughout the range ofwater resource issues. Most comments were gener-al, like ‘ ‘State needs model expertise assistance(Federal) to expedite solutions. ” Other States ex-pressed more specific technical assistance problems,e.g., “a lack of technical personnel at regional EPAlevels to review and assist the State in model main-tenance, or ‘a strong technical assistance programin ground water modeling technology is needed toprovide the capability to establish flexible predic-tive mechanisms in ground water contaminationcases,

Access to Federal Models

An important modeling problem common tomany States is the difficulty of obtaining informa-tion on or access to Federal models, data, and tech-nical assistance. The States rely heavily on the Fed-eral Government to supply such services to them;improving access to these services represents per-haps the most easily realizable opportunity for theFederal Government to contribute to State model-ing efforts.

A majority of the comments on accessibility cen-tered on the need for information about and accessto state-of-the-art Federal models. Generally, Statesare either unaware of, or unable to obtain, modelsand data to help them solve specific problems.

A periodic report or newsletter was suggested asa means of informing States about Federal model-ing activities. Alternatively, the State water re-sources research institutes could provide a meansof transferring information within each State. A na-

tional clearinghouse was also recommended bymany respondents as a good method to make mod-els available to the States. These centers would in-ventory available models and provide descriptionsto potential users. The clearinghouse could also pro-vide computer programs and documentation tousers. Respondents also suggested that a clear-inghouse could serve as a center of technical ex-pertise, model maintenance, and quality control.

Reliability and Credibility of Models

Many of the State respondents pointed out thatthe reliability and credibility of models strongly in-fluences their use. Part of this influence is due touser perceptions. As one respondent stated, “Pastexperience with awkward models can impede futuredevelopment. On the other hand, another re-spondent wrote, “As we use the one model wehave, and gain some experience, the reliability andcredibility increase.

State respondents also recognized deficiencies intechnically measurable aspects of model reliability,in particular, model calibration and validation.Many respondents mentioned problems with thereliability of specific models—a typical commentwas, ‘‘current ground water modeling programsare not sufficiently sophisticated to model the com-plex situation (especially the ground water-surfacewater interface) in this State.

The following concerns were reported as factorsaffecting the reliability and credibility of models atthe

●

●

●

●

●

●

●

State level:

the degree of uncertainty in results is not com-municated for many models;the reliability of many models has not beenestablished through repeated use;many model parameters are of questionableaccuracy;assumed values or calculations are sometimesused in the place of field data;the state of the art, in some cases, is not ad-vanced enough to provide reliable models;some decisionmakers are cautious about modeluse due to a past history of inappropriate use;andmodel development has been overemphasizedin the past, to the detriment of calibration andvalidation.

Ch. 5—Use of Models by State Governments . 107

Although comments on model calibration, verifi-cation, and validation were not numerous, mostof the responses had a common theme: the Stateshave an insufficient amount of time, resources, anddata to perform these functions.

Specific comments included:

. some Federal agencies have encouraged theuse of some models without adequately cali-brating or validating them with field data;

● Federal agencies should devote more attentionto parameter estimation and testing model sen-sitivity; and

. more comprehensive data sampling programis needed for improved validation, and esti-mates of model accuracy should be developedand provided.

Model Standardization

Various suggestions were given for Federal ac-tions to standardize the modeling process:

●

●

●

●

develop standard procedures for model use(e.g., for determining wasteload allocations);develop standard procedures for model calibra-tion;establish guidelines to govern technical devel-opment of models; andcoordinate Federal data collection efforts toassure standardization and quality control.

When models and model use procedures are notstandardized, discrepancies can result if differentmodels are used for the same purpose. One re-spondent noted that several State and Federal agen-cies use different models to analyze the same prob-lem—e. g., setting discharge standards. Coordina-tion is needed to avoid conflicting results.

Funding

Many respondents reported that low funding lev-els limit State modeling efforts. A few States re-ported that models were not used at all due to lowfunding. States generally use available funds for

adapting existing models (mainly Federal), andhave little or no funds available to develop modelsindependently. Several respondents suggested thatcoordinated Federal-State modeling efforts mightimprove the cost effectiveness of modeling.

The respondents also reported that funds areneeded for:

● computer equipment;● testing and validating models;● data collection; and● personnel and training.

Model Maintenance

From the States’ perspective, model maintenanceis a minor problem. As most of the models theyuse are federally built, they rely primarily onFederal agencies to maintain them. States generallyseek assurance that Federal agencies will maintainthe models they have developed, and will adviseStates of revisions and modifications.

A few respondents suggested funding States tomaintain needed models if Federal agencies are un-able to do so. One State cited intermittent fund-ing for model maintenance as a problem. Severalrespondents recommended seminars as an effectivemeans of informing States of model revisions ormodifications.

Documentation

Few respondents reported problems with inade-quate model documentation. The few that did typ-ically made a general comment, citing poor docu-mentation as ‘‘a barrier to model use.

Specific comments included:

●

●

●

user’s manuals are not written for the averageuser;documentation is not provided for modifica-tions in models; andlack of documentation leads to uncertainty

about the validity of model results.

—.


STATE MODEL USE IN INDIVIDUALWATER RESOURCE ISSUES

Surface Water Flow andSupply Issues

Flood Forecasting and Control

Flood forecasting and control models are wide-ly used by State agencies. Most States that indicateda need for flood forecasting models (57 percent ofrespondents) currently use them for both operationsand management decisions (43 percent) and plan-ning and policy (45 percent). Some additional Statesrely on Federal agency modeling efforts to supplyinformation needs in this area.

Major uses reported for these models include:1) delineation of flood-prone areas and estimatesof potential flood-related damage; 2) evaluation ofexisting spillway and dam adequacy (under the Na-tional Dam Safety Program); and 3) planning/de-sign and operation of flood control facilities. In-creased emphasis on nonstructural flood control—e.g., improved flood plain management—in Stateflood control strategies has made models thatdelineate flood plains and evaluate the impacts ofland-use changes on flooding patterns increasing-ly important to State efforts. A number of Statesreported a need for flood forecasting and controlmodels that can analyze small watersheds.

Federally developed models for flood forecastingand control are widely available to the States. Thosemost frequently mentioned in survey responseswere flood control models developed by the SoilConservation Service and a series of modelsdeveloped by HEC. The effectiveness of the Corpsof Engineers’ training program for these modelshas been a major factor in promoting their use atthe State level.

Results from the OTA survey of Federal agen-cies indicated that model-based information onflood forecasting and control is distributed to Stateauthorities by the National Oceanic and At-mospheric Administration, USGS, and the FederalEmergency Management Agency.


Ruins of an apartment building in Johnstown, Pa., testifyto the destructive power of raging floodwaters. Stateagencies widely use flood forecasting and controlmodels to assess the probable extent of f loodinundations and to route flows in ways that minimize

actual flood damages

Ch. 5—Use of Mode/s by State Governments ● 109

Drought and Low-Flow Forecasting

Slightly fewer than half of the States use modelsfor forecasting droughts and low flows, but manyStates acknowledged that models could be usedmore extensively. Forty-seven percent of the re-spondents saw potential applications in operationsand management, and 63 percent in planning andpolicy —the highest reported for any surface waterflow issue area. States in every region of the Na-tion are concerned with drought and low-flow con-ditions. While Western States reported use or po-tential use of these models to allocate water andestimate the capability to meet demands, the signifi-cance of flow to water quality and wasteload alloca-tions has expanded the potential use of modelsthroughout the country. Eastern States, in particu-lar, emphasized wasteload allocation in discussingpotential applications for low-flow models.

A number of Federal agencies provide appropri-ate models for State use—respondents identifiedthose of the Corps of Engineers, the NationalWeather Service, and the Soil Conservation Serv-ice. Federal agencies also supply States with model-generated information— several States mentionedUSGS in this connection. In addition, the NationalWeather Service provides low-flow forecasting forthe States.

Streamflow Regulation

Models for streamflow regulation are currentlyused by more than half of the survey respondents;approximately the same percentage of States iden-tified potential uses for these models. The Statesurvey showed greater present use of streamflowregulation models than for any other surfacewater flow issue. The survey also suggested thatthese models are now employed by most of theStates where officials have identified some usepotential.

Respondents identified a broad spectrum of ap-plications for such models, including inter- andintra-State water distribution, reservoir operationsand dam safety, low-flow effects on wetlands, wasteassiznihtion capacity, flood plain management/flood insurance, and fishery management belowdams.

Offstream Use

In many areas of the country, current stream-flows and ground water reserves are insufficient tosustain the large withdrawals required for agricul-tural, industrial, and domestic uses. Projectedgrowth in offstream demand for mining and generaleconomic development will increase conflicts be-tween instream and water quality requirements onone hand, and offstream withdrawals on the other.

Few States currently use models to analyze off-stream uses. Those that do, concentrate on plan-ning and policy for projecting future use. Only oneState specifically mentioned planning, managing,and operating offstream facilities as an area present-ly involving the use of models. However, nearlyhalf of the surveyed State officials indicated poten-tial use for offstream models. Determining the avail-ability of water for hydropower, mining, and indus-trial uses was considered a future area for modeluse, particularly in the context of comprehensiveresource management. Eastern States as well asWestern States were concerned with offstream uses.

Irrigated Agriculture

Increasing conflicts with domestic water supply

and instream flow needs necessitate sophisticatedplanning and monitoring to ensure maximum bene-fits from irrigation water. State agencies employmodels to determine current and future suppliesand demands, and to determine optimal irrigationschedules to aid farmers in conserving water. Suchmodels are currently used in about one-fifth of thesurveyed States; slightly over twice as many Statesreported a potential for model use. Potential usesinclude assessing both quantity and quality of sur-face water, as well as the effects of irrigation onground water levels. Future uses for irrigated agri-culture models include determining water rights,water demands, and stream diversion.

Domestic Water Supply

Domestic water supplies have not kept pace withgrowing demands. In many localities, supply, treat-ment, and distribution systems are inadequate, re-sulting in shortages and reduced water quaiity.Comprehensive management for conservation, and


multiple-objective planning, will become increas-ingly necessary as further growth occurs in water-sport areas.

Current use of models by States focuses on pro-jecting present and future supplies and demands,and designing supply systems to meet futur~ de-mands. Slightly under one-third of those surveyeduse water supply models. Approximately twice asmany indicated potential for model use, primarilyfor assessing the relationship between water sup-plies and water quality requirements. A few Statesindicated a need for models to analyze the efficiencyof existing distribution systems.

Instream Flow Needs

Models for assessing instream flow needs servea variety of purposes at the State level. Their usein planning and policy to meet instream flow needsfor fisheries, recreation, and hydropower wasreported by 37 percent of the States—an additional24 percent indicated the potential for such use.Fifty-five percent of the States acknowledged apotential need for operations and managementmodels, although only 12 percent currently use suchmodels.

Instream flow models are becoming increasing-ly important as tools for setting minimum instreamflow requirements. The models have further appli-cation for meeting water quality standards and allo-cating water. A few States cited data limitations asconstraints to current use. Assistance in using thesemodels is supplied by the Fish and Wildlife Serv-ice’s 1nstream Flow Group, the Corps of Engineers,and USGS.

Water Use Efficiency and Conservation

Little is currently known about the extent towhich demands for water could be reduced throughthe use of conservation techniques or improvedmanagement and planning. However, potentialbenefits in reduced expenditures for supply, treat-ment, and distribution systems were sufficient forone-fourth of the States to indicate a potential usefor models in researching these problems. This rep-resents the greatest State interest in models forresearch purposes among all surf’ace water resourceissues.

Under 20 percent of the States surveyed currentlyuse models in this area, although close to half indi-cated potential uses for such models. State use fo-cuses on models for predicting demand, and basicwater accounting models similar to those used indetermining available supplies for agricultural,domestic, and other offstream and instream uses.Greater existing and potential use was reported forplanning and policy purposes than for operationsand management.

Surface

Urban Runoff

State officials

Water

reported

Quality Issues

high potential for modeluse to determine water quality problems stemmin,qfrom urban runoff, despite low levels of current use:Two-thirds of the States saw continuing or possi-ble future uses for such models in planning andpolicy analyses, and 55 percent envisioned uses foroperations and management decisions. SeveralStates suggested that the credibility of existingmodels has limited their use.

The comprehensive planning provisions of sec-tion 208 of the Clean Water Act figure largely inState reports of existing and potential uses for ur-ban runoff models. Models are currently used todevelop control measures; to plan, construct, andmaintain storm overflow facilities; and to researchand predict local urban runoff problems. Problemsof site-specific adaptability and excessive complexityin current models were mentioned by a number ofrespondents. Respondents indicated that simplemodels for site-specific calculations could increasemodel use in this area, even though such modelsmay not be suitable for complex runoff problems.

Erosion/Sedimentation

A number of States indicated the need for im-proved erosion/sedimentation models as a priorityin water resource management. Of the State re-spondents, 53 and 69 percent saw potential usesfor these models in operations/management andplanning/policy, respectively—approximately 2 times the current level of use.

Many States reported current and potential mod-el use under section 208 of the Clean Water Act.

USGS and the Soil Conservation Service were re-peatedly cited as providing models or working joint-ly with States to determine erosion and sedimenta-tion effects.

State officials reported a wide variety of poten-tial uses for erosion/sedimentation models; amongthese are evaluating erosion control measures, de-termining canal and reservoir sedimentation rates,evaluating irrigated and nonirrigated agriculturalland uses, and planning for urban development.

Salinity

Salinity models do not appear to have a high pri-ority in State-level water resource management.Less than half the State respondents identified po-tential uses for such models, and only 6 percent cur-

rently use them for operations and managementdecisions. Potential uses include: 1) determiningthe ecological benefits of salinity reduction;2) implementing State ground water laws;3) monitoring effects of pesticides and residuals; and4) monitoring inland streams receiving brines fromsaltwater sources.

Agricultural Runoff

One-third of the States currently use agriculturalrunoff models for planning and policy, and nearlydouble that figure-57 percent—anticipate poten-tial uses. A number of States use models in connec-tion with section 208 of the Clean Water Act; othersspecified future uses in planning and regulation ofanimal wastes as well as in developing and imple-menting fertilizer and pesticide management plans.


Concern over the effects of agricultural runoffis reflected in actual and potential model usereported by States for research in this area. Whileonly 8 percent of State respondents presently useagricultural runoff models for operations and man-agement decisions, 14 percent use them for re-search, and 27 percent identify future researchpotential for such models.

Airborne Pollution

Several of the comments indicated that some re-spondents misinterpreted this question. These re-spondents may have identified model use for Stateair pollution control, rather than for the specificpurpose of determining the effects of airborne pollu-tion on water quality. However, two States identi-fied potential use of models for acid rain abatement.

Wasteload Allocation

States use models extensively for determiningwasteload allocations. Two-thirds of the Staterespondents indicated present use for operationsand management decisions, and 57 percent re-ported current use in planning and policymaking—more than for any other water resource-related pur-pose. Survey responses suggested that the relativelylong history of model use in this area has made thesemodels widely available to States. Most States thatrecognize potential uses for these models are pres-ently using them. The ubiquity of wasteload alloca-tion problems, and the expanded State role in waterpollution control, has contributed to widespreadwasteload allocation model use. Model use was spe-cifically mentioned for implementation of sections201, 208, 303, and 402 of the Clean Water Act.

Many States, however, stated that these modelsneed refinement. Further validation of reactionrates and other necessary parameters, standardiza-tion of models for different geographic regions ofthe country, and evaluations of the magnitudes oferror in predictions, were among the improvementssuggested. Several States also identified the needfor standard wasteload allocation models for thefollowing purposes: evaluating the effects ofdischarges into nontypical streams (swamps,estuaries, and intermittent streams), designingstandard waste treatment facilities, and determin-ing the need for advanced waste treatment.

Thermal Pollution

State water resource professionals reported thatavailable thermal pollution models are simple andaccurate. About one-fourth of the surveyed Statesreported current use of such models, and about halfof the respondents recognized potential uses forthem. A number of States noted that all necessarythermal modeling under section 316(B) of the CleanWater Act is performed by power-generating orother industries, and is merely reviewed at the Statelevel. Others cited the Corps of Engineers, EPA,and USGS as providing thermal modeling servicesfor States or in conjunction with State efforts.

Toxic Chemicals

Many States identified the development of mod-els to deal with toxicants as a top priority, with sig-nificant potential for future applications. As withother recently recognized problems, about one-fourth of responding States identified a need forsuch models in research, although few of the re-spondents currently use them for any purpose. Po-tential uses, both for operations/management andpolicy/planning, were identified by 55 percent ofthe surveyed officials.

Respondents indicated that models are neededfor determining sources of toxicants, toxicanttransport and removal mechanisms, and for settingtoxic chemical effluent standards. Some States iden-tified data availability as a limiting factor in mod-eling.

Drinking Water Quality

About half the States reported potential uses fordrinking water quality-related models, primarily toassist in setting standards required under the SafeDrinking Water Act. States also noted uses for im-proved models in determining the effects of waste-water discharges on drinking water quality, as wellas for specific problems such as the effects of min-ing and low flows. A small number of States indi-cated that these models were of high priority; fewerthan one-fifth of the States indicated that they arecurrently used.

Water Quality Impacts on Aquatic Life

Several States stressed the need for further re-search and improved modeling techniques to gage


the effects of changes in water quality on aquaticlife. Credibility problems of current eutrophicationmodels were specifically mentioned. Survey com-ments suggested that improvements to aquatic lifeimpact models are of major concern to respondentsthroughout the country.

Sixty-nine percent of surveyed State officialsidentified potential application for these models inplanning and policymaking; 55 percent identifiedfuture operations and management uses—in bothcases about twice the existing level of use. Officialsidentified a variety of uses for aquatic life impactmodels, including evaluating permit applications,pollution control program planning, and compre-hensive basin planning.

Ground Water Issues

Ground Water Supplies and Safe Yields

Over half the surveyed State personnel indicateduse of models for determining ground water sup-plies and availability—the highest reported groundwater-related model use. Many acknowledged useof USGS models and modeling expertise in devel-oping ground water modeling programs. As mightbe expected, the use of such models by WesternStates in determining water rights was mentioned

frequently; however, ground water supply modeluse was equally evident for Eastern States.

Ground water supply models are presently em-ployed by most of the States that reported some usepotential; however, many States place a high pri-ority on improving these models. The lack of his-torical aquifer performance data and the extensivecurrent data requirements of ground water modelswere repeatedly cited as hindering State modelingefforts.

Conjunctive Use of Ground and Surface Water

A higher percentage of survey respondents re-ported potential uses for models of the interaction

Photo credits: @ Ted Spiegel, 198.2

Lake Tahoe, Nev., has long been billed as one of the world’s clearest bodies of water. Rapid development alongshorelines, however, has greatly increased the flow of nutrients into the lake, accelerating natura{ eutrophication rates,creating nuisance algal growths, and endangering Tahoe’s ecological balance. Models have been used both to assessthe effects of development and to evaluate the effectiveness of centralized sewage treatment in preventing theeutrophication process. In underwater labs above, University of California biologists and hydrological scientists useradioactive trace elements to monitor nutrient levels in the water. Meanwhile, crews build sewage transport facilities

to divert wastes around Lake Tahoe for treatment and release in less sensitive areas

114 ● Use of Models for Water Resources Management, Planning, and Policy— ———

between ground water and surface water than forany other ground water-related issue. Such modelsare valuable for developing comprehensive basinplans and for comprehensive water supply manage-ment. Over 35 percent of the surveyed States cur-rently employ conjunctive use models—after supplyand safe-yield models, they are the most extensivelyused model for ground water management. SomeStates reported using models developed by USGS;a number of others observed that the lack of fielddata constitutes a bottleneck to using these models.

Accidental Contamination of Ground Water

Although over half the States indicated poten-tial for future use of models that predict the spreadof contaminants in ground water, fewer than 10percent currently employ them. Gaps in currentknowledge about the behavior of contaminants insome types of ground water systems and data limi-tations upon the construction and validation of suchmodels hinder more widespread use. Survey re-spondents envisioned such future applications asdetermining effects of various pollutants andrequirements for control measures, devising warn-ing systems for the public, and predicting longerterm contamination.

Agricultural Pollution to Ground Water

Determining the effects of agricultural pollutantson ground water is also a modeling area where re-ported potential for State-level use is high, althougha low percentage of States currently use models.Seventy-one percent of the surveyed State officialssaw potential uses for such models in planning andpolicymaking, and 57 percent envisioned operationsand management uses— current uses amount to lessthan one-sixth of these potential use levels. The of-ficials specified potential uses for these models insection 208 planning, determining effects of various

“1-lcontaminants and corrective measures, planningallowable point source pollutant loads, and supple-mental monitoring for regulatory purposes. A num-ber of States indicated that data on pollutant move-ment is a limiting factor in model development anduse.

Ground Water Pollution From Waste Disposal

Survey respondents indicated that lack of dataand poor understanding of ground water chemistry

are primary limitations on States’ abilities to modelthe spread and effects of pollutants to ground waterfrom waste disposal sites. Limited understandingof the reactions and diffusion of pollutants in mixedgeological formations, and deficiencies of data forvalidation purposes, were cited as specific problems.While potential uses were reported by a high pro-portion of State officials-71 percent for planningand policymaking, 59 percent for operations andmanagement decisions—these models are currentlyused by only one-fifth as many States. Anticipateduses include determining infiltration from sanitarylandfills and mine waste disposal.

Saltwater Intrusion

Several States indicated that models for deter-mining saltwater intrusion to ground water suppliesare water resource management priorities; how-ever, interest is naturally limited to coastal areasand States with major inland saltwater bodies.

The acquisition of sufficient data to verify suchmodels was repeatedly cited as a significant need.State officials envisioned several management usesfor these models, in particular establishing rechargeareas, as well as determining acceptable pumpingrates and designing well fields.

Economic and Social Issues

Effects of Pricing on Use

Models that evaluate the effects of pricing onwater use were seen as having potential planningand policymaking uses by 59 percent of the Statesurvey respondents. Respondents referred to com-prehensive planning efforts under title III of theWater Resources Planning Act and section 201 fa-cilities planning under the Clean Water Act as areasin which models are needed. Some States suggestedthat current models are not precise evaluation tools,and that their importance may be limited to placeswhere strict conservation and reuse laws apply.Models are currently used by a small proportionof surveyed States, primarily in planning and re-search.

Costs of Pollution Control

Slightly fewer States indicated a need for modelsto evaluate pollution control costs than for mostother types of social and economic modeling. Su~-

Ch. 5—Use of Models by State Governments . 115

gested potential uses include assessing the effectsof alternative waste treatment strategies on firmbehavior, and determining the impacts of pollutioncontrol costs on individual industries. At present,such models are used in only a few States.

Cost/Benefit Analysis

Use of cost/benefit analysis models for planningand policymaking was envisioned by over half theState officials; 23 percent of those surveyed current-ly use such models for planning. Some current usersnoted, however, that models evaluating the cost ef-fectiveness of alternative actions are more applicablethan cost/benefit models. Several respondents con-sider the cost/benefit concept too subjective to be

adequately modeled. A number of States indicatedthat improved models for cost/benefit analysiswould be highly desirable, and one respondent spec-ified a need for a combined hydrologic/economicmodel for cost/benefit studies.

Regional Economic Development Implications

Models for evaluating economic implications ofwater resources development and policy are usedby States in the context of planning efforts undersection 208 of the Clean Water Act and title III ofthe Water Resources Planning Act. Slightly fewerthan one-half of the surveyed State personnel pre-dicted future uses for these models; 22 percent indi-cated current planning uses. Officials mentioned

.—


such specific uses as predicting population andeconomic growth in water-short areas, comprehen-sive river basin planning, and determining the ef-fects of ground water depletion.

Forecasting Water Use

Forecasting water use with models was con-sidered possible at the State level by 59 percent ofsurvey respondents; 31 percent currently use suchmodels for planning and policy purposes. SomeStates doubt the reliability of these models in theircurrent forms, and suggested that existing data areinadequate to justify sophisticated model forecast-ing. A variety of applications are projected forimproved models; ensuring that water qualitystandards are not violated due to overallocation ofsupplies, and evaluating existing laws regulatingground and surface water use were repeatedly men-tioned, as well as simple projections of futuredemand.

Social Impact

Relatively few States indicated a need or poten-tial use for social impact models. While one Stateofficial suggested development of a general modelthat could be calibrated to local conditions, littleState-level interest in such models was expressed,and some respondents questioned their reliability.

Risk/Benefit Analysis

State officials reported a variety of potential usesfor risk/benefit analysis models, including dam safe-

ty analysis, flood management, and toxic wastemanagement. Slightly fewer than half foresaw fu-ture planning and policy uses for these models intheir States; 10 percent currently employ them.

Competitive Water Use

Fifty-nine percent of the surveyed officials in-dicated the possibility of future planning and policy-making applications for models of competitive wateruse; one-fifth reported that such models are cur-rently used by their States. A few States reportedthat these models are a high priority for analyticalwork. Reported potential applications include:basinwide water supply planning, water rights de-terminations, and the evaluation of conflicts be-tween water supply and water quality objectives.

Unified River Basin Management

Models for unified river basin management arecurrently used by a greater percentage of Statesthan any other socioeconomic model: one-third ofthe survey respondents indicated that such modelsare currently employed for planning and policy-making, and nearly twice as many foresaw futureuse potential. State-level personnel mentioned suchuses for these models as regional water supply plan-ning, integrating water quality considerations withbasin development, planning studies to evaluate dif-ferent management options, and planning and con-trol of development.

Chapter 6Modeling and Water Resource Issues

Contents

Page

Surface Water Flow and Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Types of Models Used in Surface Water Flow and Supply Analysis . . . . . . . . . . . . 121Water Availability Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Water Use Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Evaluation of Currently Available Surface Water Flow and Supply Models . . . . . 130

Surface Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131Types of Models Used in Surface Water Quality Analysis . . . . . . . . . . . . . . . . . . . . 132Nonpoint Source Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134Point Source and General Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138Evaluation of Currently Available Surface Water Quality Models . . . . . . . . . . . . . 141

Ground Water Quantity and Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Types of Models Used in Ground Water Resources Analysis . . . . . . . . . . . . . . . . . 144Ground Water Quantity Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146Ground Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Evaluation of Currently Available Ground Water Models . . . . . . . . . . . . . . . . . . . . 151

Economic and Social Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152Basic Analytical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Types of Models Used for Economic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155Other Social and Economic Analytical Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . 155Economic and Social Issues in Water Resource Analysis . . . . . . . . . . . . . . . . . . . . . 156

TABLES

Table No. Page

7. Surface Water Flow and Supply Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 1308. Surface Water Quality Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1429. Ground Water Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Chapter 6

Modeling and Water Resource Issues—— —— —

Government agencies normally use water re-source models to address specific resource problemsunder their jurisdiction. While most problems andmodel applications have unique aspects, it is possi-ble to generalize about the kinds of problems mostfrequently encountered in water resource manage-merit — and the analytic techniques used to under-stand them. This chapter describes 33 of the Na-tion’s most prevalent water resource issues, brief-ly assesses the modeling capabilities associated witheach of them, and evaluates the model types usedto analyze them. Previous chapters have focusedon generic issues and problems involving water re-source models; this chapter deals with specific waterresource concerns and the capacity of models to ad-dress them. It is provided as a layman’s introduc-tion to the relationship between models and real-world water resource issues.

Water resource concerns can readily be groupedaccording to four major subject areas: 1 ) surfacewater flow and supply; 2) surface water quality;3) ground water quantity and quality; and 4) economic and social models. The areas differ signifi-

cantly with regard to levels of current knowledge,kinds of issues addressed, and types of models andlevels of modeling expertise currently available.Each is discussed in a separate section of thechapter.

The first three subject areas deal primarily withphysical processes, and are described according toa common format: 1) introduction; 2) types of mod-els; 3) issues addressed; and 4) evaluation of cur-rently available models. Each subject-area modelevaluation follows a format that reflects the prob-lems addressed, processes modeled, and mathe-matical techniques most commonly used withineach scientific discipline. The last area, economicand social models, deals with the social science in-formation needed to support water resource deci-sionmaking. Models of social sciences processes dif-fer fundamentally from those of physical processes,and are extremely diverse; consequently, a largersubjective component is involved in evaluatingthem. No formal evaluation of economic and socialmodels was undertaken for this study.

SURFACE WATER FLOW AND SUPPLY

Introduction

Managing surface water today virtually requiresthe use of a wide range of computer-based analyticaltechniques, ranging from sophisticated models thatforecast the probable frequencies and extents ofserious floods, to relatively simple computer modelsfor simulating the operational characteristics of farmirrigation systems. All of these models provide in-formation to help assure that water will be availablewhen and where needed, or will not intrude whenor where it is not wanted. Models permit the analystto: 1 ) make reasonable predictiom of natural events,and 2) estimate the favorable and adverse cose-quences of man’s attempts to improve the reliabili-ty of’ freshwater production, distribution, and useSyst ems.

Water resource models are widely applicable toproblems in policy, planning, operational manage-ment, and regulation of the Nation surface waterresources. Existing models are widely used to planand operational~ manage most water availability y andwater use problems. Model use is not as commonfor policy and regulatory activities, partially becauseexisting models are not well adapted to decision-making in these governmental areas, and partial-ly because such decisions have traditionally beenbased more on qualitative than quantitative criteria.

Models used to analyze surface water flow andSupply problems can be subdivided into two broadcategories, for which both current model capabilitiesand future promising roles are somewhat different.For each of the two broad categories-water avail-

119


ability and water use—four specific problem areasare discussed later in this section. Although theseproblem areas are not all-inclusive, they encom-pass the major surface water quantity problems fac-ing the Nation. Each problem area is specificenough to permit discussion of successes and fail-ures in the use of models, and development of rec-ommendations for appropriate model uses. An eval-uation table for the models used in each problemarea is presented later in this chapter (see table 7).

To introduce the modeling techniques that ap-ply to surface water flow and supply issues, appli-cable model types are discussed below. Generally,the model types are not limited to one specific prob-lem area—each model type may be applicable toseveral issues. References, keyed to over 30 modelclasses, are provided in appendix D to this report.

Availability of Water

Water availability analysis-which encompassesbut is not limited to the sciences of hydrology andmeteorology —uses models extensively. While mod-els are less frequently used in policymaking thanfor planning and management, numerous examplesof model use for determining water availability canbe cited throughout private industry and at all levelsof government. In fact, a major problem in usingmodels to analyze a given water availability prob-lem is the difficulty of selecting—from among theplethora of available models—the most appropriatemodel for the problem at hand.

Determining the availability of surface water re-quires analyses of the hydrologic cycle, typically in-cluding calculations of streamflow magnitude, dura-tion, and frequency; and the temporal and spatialvariations of these streamflow characteristics. Aspecific problem may require analyzing one or moreof these characteristics at a single point along astream—for instance, to determine the extent of aflood plain—or it may require coordinated analysisat a large number of locations in a watershed (e. g.,to operate a series of multiple-purpose reservoirs).

Solving problems of water availability, however,requires more than understanding and modelingthe hydrologic cycle. Many problems arise becauseof the need to alter natural hydrologic processes for avariety of reasons: to reduce flood hazards; toreduce the risks of drought and low streamflow; to

change the timing and distribution of streamflow;and to improve management of this increasinglyscarce renewable resource for a variety of beneficialpurposes. Certain types of human intervention innatural hydrologic processes can be modeled rea-sonably well, but many types of modifications andcontrols introduce conditions that may be too com-plex to simulate or forecast accurately. In dealingwith water availability problems, one must distin-guish between the capability to model natural proc-

Ch. 6—Modeling and Water Resource Issues ● 121— —

esses, and current capabilities to model the effects ofhuman management efforts on these processes.

Water Use

Models have been used less frequently to analyzewater use than to analyze water availability. Ex-cept for agricultural irrigation needs in arid areasof the Western United States, water availability hashistorically been so much greater than water usethat there was little or no requirement for sophisti-cated analysis. Consequently, almost no effort wasexpended on developing models to analyze wateruse. In recent years, however, increasing demandfor relatively large quantities of water—e. g., forenergy development—and the droughts of the1960’s in the Northeast and the 1970’s in theMidwest and West, have stimulated the develop-ment of models for planning and operations/man-agement. Nonetheless, these recent developmentsare not yet reflected in widespread adoption of wateruse models.

Water availability and water use also differ inthe kinds of information they require for model con-struction. Most problems of water availability areconcerned with physical principles and relationshipsthat are reasonably well understood, and are conse-quently easier to model successfully, while mostwater use problems involve not only physical fac-tors but also social and economic factors—many ofwhich are less well understood. The lack of knowl-edge about interrelationships among economic, so-cial, and physical factors is compounded by a lackof data on social and economic factors related towater use. Social and economic models are dis-cussed in more detail later in this chapter.

Types of Models Used in SurfaceWater Flow and Supply Analysis

Of the wide array of models used to analyze vari-ous aspects of surface water flow and supply, themost important ones fall into two broad modelclasses—process models and statistical models. Proc-ess models simulate or describe the flow of waterthrough a watershed or water body using known,physical relationships. Statistical models use empir-ically derived relationships—often with no inherentphysical meaning—to estimate the probability of

a flood or drought, the magnitude of a flood peak,or even regional water use demands.

Watershed Process Models

Watershed process models follow the movementof water from the time it reaches the Earth as pre-cipitation until it flows into a lake or stream, reachesa ground water aquifer, or evaporates back to theatmosphere. Models used to describe the dynamicsof water over three distinctly different types of landareas are described in this section: 1) watershedsimulation models, which describe the movementof water over large, nonurban areas; 2) agriculturalsoil/water interaction models, which are designedto specifically address agricultural water problems;and 3) urban runoff models, which describe themovement of water through urban areas.

Watershed Simulation Models.—Simulationmodels describing the movement of water overlarge, nonurban areas are used to estimate floodpeaks, low flows, and volumes of water availableto users. They are most useful where historicalstreamflow data are sparse or nonexistent. Thesesimulation models are powerful planning tools thatcome far closer to replicating measured flows thanwas previously possible. Four types of processesmust be included in watershed simulation models:1) the movement of rainfall into and through thesoil; 2) ground water flow to streams (called base-flow); s) the l0SS of water to the atmosphere fromevaporation and evapotranspiration from plants;and 4) in colder climates, snow accumulation andsnowmelt.

Watershed soil/water process models are used to repli-cate water movement into and through the soil for:1) estimating flood peaks during storm events;2) estimating water supply on an annual basis; and3) estimating low flows during dry periods. Cur-rent models are most reliable for estimating lowflows and total annual runoff volumes, and less so(but still acceptable) for calculating short-term flowsand flood peaks.

During low-flow periods, except in very humidclimates, water enters streams primarily by seepagethrough the soil profile or from aquifers. Mostbaseflow models do not use advanced ground watermodeling techniques to estimate flow rates, but

8 + - [ 83 n - 82 - 3


rather use observed flow patterns during long dryperiods as an estimate of ground water flow tostreams. They are quite adequate for estimatingbaseflow during floods, and reasonably good forestimating low flows.

Evaporation from water surfaces and evapotransPira-

tion from plants are modeled to simulate the soil-drying process. The drier the soil, the more precipi-tation will infiltrate and be stored during the nextstorm. The results are more reliable for watershed-wide average soil moisture than for specific loca-tions within the watershed, but are difficult to val-idate because of the scarcity of field data.

For areas where snow remains on the ground formore than about a month, the processes of snowaccumulation on the ground and snowmelt in thespring must also be considered. Total runoff vol-umes from snowmelt can be simulated quite wellfor forecasting water availability during the follow-ing summer, but models are not very reliable forsimulating snowmelt flood peaks (magnitudes arebad and timing is worse), because of the difficultyof predicting spring weather conditions. However,in areas where the snowmelt occurs relatively slow-ly, the models are adequate for most purposes.

Agricultural Soil/Water Interaction Models.—Simulation models similar to the watershed processmodels described above have been developed toassist in agricultural water conservation. Four typesof models are currently available:

Soil/water process models are sometimes spe-cialized to estimate moisture conditions in a smallplot, rather than average conditions over an entirewatershed. These P!ot--size soil/water process models areused for agricultural water management and land-use decisionmaking. This approach has potentialfor improving crop management decisions, butthese models are not yet very accurate.

Models that analyze the effects of local climaticvariation on @ant water use are valuable for allocatingavailable water supplies. Acceptable results are ob-tained on an annual or seasonal basis, but estimatesof shorter term demands (less than 1 month) areunreliable.

The extent and duration of the soil’s capacity tohold irrigation water for plant use has been modeledto assist in farm water management and irrigation

system design. Results from irrigation water demandmodels are generally reliable for estimating averageannual water use, but poor for estimating how useis distributed over the irrigation season.

In areas where excess water is a problem, soilmoisture can be reduced by subsurface tile or ditchdrains to make the land more productive. Landdrainage models estimate flow rates for system designand residual field moisture conditions for croppingdecisions. These models achieve adequate to goodresults.

Ch. 6—Modeling and Water Resource Issues ● 123

Urban Runoff Models .—Urban runoff modelsgenerate simultaneous flows from many small ur-ban watersheds, and aggregate them into floodflows for specified downstream points. These mod-els are sophisticated tools for urban flood plainmanagement and for designing and operatingurban storm-water control systems. They have re-ceived widespread use over the last few years andpromise a great deal for the future.

Stream Process Models

Stream process models begin describing themovement of water at the point where watershedprocess models end— once the water enters astream, lake, or reservoir. In this section, two topicsare discussed: 1) models that describe the flow ofwater through streams, lakes, and reservoirs, usedprimarily for flood control; and 2) models that de-scribe the movement and erosion of sediments(called alluvial processes) within water bodies.

Channel Process Models.— Channel processmodels describe the flow of water through streams,lakes, and reservoirs. They are often used for reser-voir operations during flood conditions and for floodplain management. In general, they provide veryreliable results when accurate information on chan-nel and flood plain geometry is available. The fol-lowing models are included in this category:

F[ood channel routing models are used for operatingflood control facilities or issuing warnings duringflood emergencies. These models provide quite reli-able estimates of changes in flow depth and veloc-ity as water moves downstream in well-definedchannels. However, the estimates are less accuratefor larger floods where streams overflow theirbanks, and are particularly unreliable where flowsspread out over large flat areas.

When flows enter a lake or reservoir they increaseboth water depth and outflow through spillways orother outlet controls. Lake and reservoir routing mod-els are accurate enough to size spillways to ensuredam safety and for controlling spillway gates to min-imize downstream flood damage.

Flood plain management relies heavily on ac-curate mapping of flood hazard areas. Models canestimate flood heights and—when combinecl with

accurate topographic maps—the geographic extent

of flooding. The most accurate results from floodinundation models are achieved when the stream flowsbetween stable channel banks, and the least reliableestimates are obtained on broad flat flood plainswhere flows are deflected by small obstructions andare spread in random patterns from one event tothe next.

Special channel routing models are used to deter-mine the downstream areas that would be inun-dated if a dam failed. The reliability of dam failuremodels is uncertain, because few historical recordsare available on the hydrologic conditions existingat the time of failure.

Alluvial Process Models. —The dynamics ofchannel erosion and sediment deposition have beendescribed through modeling techniques. The re-sults, however, are approximate, and a great dealmore research is needed to make these models reli-able. Two important problem areas include reser-voir sedimentation and channel erosion:

Re.sewoir sedimentation models have been developedfor determining the amount of sediment washedinto a reservoir that is deposited on the bottom, thusreducing its water storage capacity. These modelsdo not have the accuracy desired for estimating

useful reservoir life, unless supported by empiricalrelationships from reservoir surveys.

Flowing water can erode the channels throughwhich it flows and deposit sediment loads down-stream. Problem locations can be identified byusing channel erosion and deposition models, but theresults are not reliable enough for channel designor maintenance management.

Statistical Models

When causative mechanisms are not well enoughunderstood to construct process models, or the ex-pense of developing or using process models is notjustifiable, statistical models are often used in theirplace. Statistical models can be used wheneverenough data are available to estimate the relation-ships between factors of interest—without havingto understand the underlying physical processes.

Three types of models are presented in this sec-tion: 1) statistical flood models, which yield resultssimilar to combined watershed and stream process

124 Use of Models for Water Resources Management, P/arming, and Policy-— — . — . .

models; 2) flood and drought frequency analysis,used for sizing flood control or water supply proj-ects; and 3) water use statistical relationships, whichare used to estimate demands for water.

Statistical Flood Models .—Statistical models—simpler in approach than the process models dis-cussed earlier—have been developed to estimateflood flows and areas of inundation. These tools areuseful for structural design or reservoir operationin situations where more sophisticated continuoussimulation models are not justified. Three commonapproaches—flood formulae, regional flood for-mulae, and unit hydrography models—have beenextensively used.

Flood formulae are simple equations for estimatingflood peaks from watershed characteristics. Theyhave been used for years to help design small struc-tures, but can only be recommended for relativelysmall projects. Much more reliable for structuralplanning are regional flood formulcw. These equationsare derived statistically using historical data andcan be used for estimating flood peaks on streamsthroughout hydrologically uniform regions.

Another approach, called unit hydrography mode/-ing, is based on the assumption that a given amountof runoff from a given watershed will always resultin similar flood patterns. These models have longbeen used to establish flow patterns for designingflood control reservoirs. The results are reasonablefor reservoir design to prevent flooding by a stormevent of specified size, but less than desirable forreservoir operation.

Flood and Drought Frequency Analysis.—Several approaches are available for estimating thefrequency of occurrence of floods and droughts. Thepurpose of these models is to determine the econom-ically optimal size of flood control or water supplyprojects. The available statistical models providereasonable to good results for most applications.

Flow frequency models analyze historical series offlood peaks, flood volumes, or low flows to providean estimate of the maximum or minimum flowmagnitudes to be expected, on the average, no morethan once every 10 years, 100 years, or some otherperiod. The reliability of these models improveswith longer record lengths. Once the statistical char-acteristics of streamflow have been determined, an-

nual data generation models can generate annual runoffsequences that match the size, probability distribu-tion, and other patterns of historical flows for usein determining reservoir capacity. The results aregenerally good for monthly, seasonal, or annualtime periods.

Another important use of statistical models is forassisting reservoir design. By accounting for all in-flows (stream and precipitation) and outflows (evap-oration, uncontrolled releases, and project waterdelivered) over long time periods, capacity require-ments for designing reservoirs and rules for operat-ing them during dry periods can be determined.Reseruoir water accounting models provide excellent re-sults if reliable data are available to describe inflowand storage volumes.

Water Use Statistical Relationships.—Wateruse demands (use as it would be if unconstrainedby supply shortages) are estimated either from his-torical data or simulation models. Two types ofmodels have been applied on broad regional scales:

Regional water use relationships statistically estimatepeak, annual, and seasonal variations in water userates. Their results are generally adequate for esti-mating the volume of water needed over long peri-ods, but not for estimating peak demands.

Annual use generation models, similar to models thatsimulate streamflow, have potential for generatingestimates of monthly to annual water use. Theseresults may then be combined with supply estimatesfor the same period to improve water supply reser-voir design or operating procedures. However, reli-able models of this type are not widely used.

Water Availability Issues

Flood Forecasting and Control

Floods rank among the most prevalent of naturalhazards. About half of the Nation’s communities,and nearly 90 percent of its largest metropolitanareas, are located in flood-prone areas. Despite ex-penditures of more than $13 billion for flood con-trol over the last 50 years, flood damage continuesto rise each year. Residential, commercial, and in-dustrial development in flood-prone areas outstripsour ability to provide protection, while the econom-ic value of existing damage-susceptible property in-creases as well.


Available models and the hydrologic data re-quired to operate them are generally adequate forflood control planning and management. Even insituations where hydrologic records are not as ex-tensive as designers require, statistical methods anddigital simulation models provide sufficient infor-mation for designing flood control and protectionstructures.

Although there are isolated cases of design defi-ciencies in flood control projects, most of the hun-dreds of existing projects function as planned.When flood damage occurs in ‘‘protected’ areas,it is generally not due to faulty flood forecastingor to failure to operate flood control projects prop-erly. Rather, damages occur because the flood mag-nitude exceeds the degree of protection providedby the project. However, when flood magnitudesexceed the project’s protective capabilities, accurateforecasting becomes essential for minimizing losseven if it cannot prevent loss. A poor forecast of aflood exceeding the control structure’s capacity cancause serious mismanagement, and greatly increasethe resulting damage. Improvement is needed inthe accuracy with which flood characteristics arepredicted once the event is under way.

While models and predictive methods for floodcontrol planning and management are generallysatisfactory for design, engineering, and routineoperation of traditional areawide flood control struc-tures, flood control planners are increasingly con-cerned with nonstructural measures for reducingflood damage. Consequently, new needs for modelsand data aimed at nonstructural approaches havearisen. Many of these measures are regulatory innature, and frequently address areas considerablysmaller than those associated with larger scale struc-tural projects. As a result, many traditional floodcontrol models are not suited for planning and man-aging nonstructural approaches. These traditionalmodels are based on a ‘‘ macrohydrologic’ scale,in which model assumptions and data requirementsare scaled to hydrologic analyses for relatively largewatersheds. However, when these models are ap-plied to the ‘‘ microhydrologic’ scale, they are oftenfuuncl to be inappropriate, either because detaileddata are not available at the microscale level, orbecause the macroscale assumptions are not consist-ent with conditions on the smaller scale.

Good hydrologic analysis on a microscale basisrequires considerably more data than macroscaleanalysis; consequently, geographic consistency indata on soil types, vegetation, land use, precipita-tion, and surface runoff is considerably more impor-tant in microscale analysis. As a result, the modelsbeing developed for microscale analysis frequent-ly depend on the availability of spatial data bases—i.e. , sets of computerized ‘‘maps’ with a geo-graphically consistent set of data on an area’s physi-cal characteristics. Although the needed data arefrequently available on printed maps, the effort re-quired for digitizing and maintaining the data sig-nificantly limits widespread use of these models atpresent.

Model use for the regulatory aspects of flood con-trol has been extensive in both flood plain manage-ment and flood insurance programs. Two basictypes of models—flood inundation models and floodfrequency models—have been widely employed.Flood inundation models are used to delineate floodhazard areas. When properly used, the availablemodels are relatively noncontroversial. However,problems have occurred when the analysis is per-formed for part of a stream at one time and for ad-jacent parts at another time, with the result thatthe flood hazard areas fail to coincide at the bound-aries of adjacent areas. Since the primary purposeof this analysis is regulatory in nature—identifyingareas subject to flooding so that appropriate restric-tions in use can be implemented—it is not surpris-ing that even minor inconsistencies in flood hazardarea delineations are major sources of controversy.

A larger source of controversy has been the useof statistical flood models to determine the magni-tude of flood associated with a specified recurrenceinterval (usually 100 years). Each of the half dozenor so major flood frequency theories (and the mod-els based on them) produces somewhat different re-sults in a given setting, even when the same dataset is used for all cases. In some instances the dif-ferent theories give considerably different results,so that estimates of the size of a 100-year flood, forinstance, may vary by a factor of two or more. Withthat large a variation in flood magnitude, there isan attendant, but usually somewhat smaller, varia-tion in flood hazard area—since the amount of landsubject to development restrictions varies with the

126 Use of Models for Water Resources Management, P/arming, and Policy

estimate of the 100-year flood magnitude. Floodfrequency estimates at different points on the samestream using different models (or even at the samepoint using different models) often produce differentresults, causing a tremendous amount of confusionand controversy. Since the differences are not dueto error in calculation, but to fundamental differ-ences in the assumptions of the models, the differ-ences are essentially irreconcilable. The need forconsistency was a major factor in the Water Re-sources Council’s decision to recommend a uniformtechnique (or model) for use by Federal agenciesin performing flood frequency analyses. That deci-sion has eliminated some, but not all, of the contro-versy.

LOW-FlOW and Drought Forecasting

Low streamflow is caused primarily by physicalphenomena, while droughts result from the jointoccurrence of low streamflow and high demand—acondition due to social and economic causes as wellas physical ones. Modeling capability for forecastingand managing low streamflow per se is as highlydeveloped as for flood forecasting. However, fromthe point of view of drought management, whichrequires an ability to modify both water availabilityand water use, the available models are less satis-factory.

The major difficulty in forecasting low flowsstems from problems in choosing appropriate sta-tistical procedures for determining how often to ex-pect low flows of a specified volume and duration.Most of the theories used in hydrologic probabilityanalysis are based on the concept of independ-ence—the idea that two or more “events’ are total-ly unrelated to one another. In the case of lowstreamflow, analysts are normally concerned withthe quantity of streamflow during a specific periodof time. Frequently, however, the specified periodis part of a more extended period of low flow pro-duced by general climatological and meteorologicaltrends. For this reason, it is difficult to ascribe prob-ability estimates to low-flow ‘‘events.

Perhaps because of the difficulty of determininglow-flow probabilities, a common practice in plan-ning and designing facilities for low-flow manage-ment has been to design for the ‘ ‘drought of rec-ord, i.e., the most severe low-flow period experi-

enced in recorded history in a given watershed.Because of natural variation and differences in thelength of available hydrologic records in differentwatersheds, the ‘‘drought of record’ in some water-sheds is very severe—perhaps with an estimated re-currence interval of 300 years or more—while inother watersheds the drought of record may havea recurrence interval of 20 years or less.

When the drought of record is used as a designstandard, some facilities are inevitably underde-signed and others are overdesigned. Thus, whilefailures of flood control structures are rare, seriousinaccuracies in low-flow management facilities arerelatively common. Although alternative methodshave been developed for calculating streamflow se-quences of long duration based on statistical anal-ysis of relatively short historical hydrologic records,planners have been reluctant to accept designsbased on statistical methods that differ substantiallyfrom designs based on the “drought of record. ”Considerably more work is needed on the use ofstatistical methods for planning, designing, oper-ating, and managing low-flow control facilities.

Public policy for dealing with low-flow problemshas focused more on water availability y policy thanon water use in low-flow periods—except with re-gard to competition among uses (irrigation, hydro-electric power, municipal water supply), which willbe discussed in the following subsection on stream-flow regulation. Little use has been made of modelsfor regulatory aspects of low-flow management, ex-cept where interstate compacts or judicial decisionshave forced governmental entities to apportion lowflow among competing users. In general, availablemodels seem to be adequate for these needs.

Streamflow Regulation

The Nation has invested billions of dollars infacilities to regulate streamflow for a variety of pur-poses: to reduce flood damage; to generate hydro-electric power; to provide stable navigation chan-nels; to provide dependable surface water suppliesfor municipal, industrial, and agricultural uses; toimprove fish and wildlife habitat; and to providerecreational opportunities. Federal agencies alonehave constructed hundreds of structures that regu-late streamflow for one or more of these purposes.Thousands more have been constructed by other

Ch. 6—Modeling and Water Resource Issues ● 127— —

governmental entities, private enterprises, and indi-viduals. Most of these facilities are passive; i.e.,they require little, if any, operational management(other than routine maintenance) to accomplishtheir intended purpose. Levees, ungated diversionstructures, and small dams with ungated spillwaysare typical facilities that require minimal opera-tional management.

Hundreds of these existing facilities, however,are not passive. They are large, complex structuresserving many purposes and requiring intricatedaily, hourly, or sometimes even minute-to-minuteoperational management to achieve their intendedpurposes. Myriad conditions, criteria, and datamust be identified and evaluated each time an op-erational decision is made. Some operationalcriteria are based on fixed conditions (e. g., thosethat ensure the safety of the structure) while othersare based on changing phenomena (e. g., currentand future weather conditions). Operational man-agement is further complicated in multipurposeprojects because some purposes are competitive (adecision favoring one purpose has an adverse ef-fect on some other purpose), while others are com-plementary (a decision favoring one purpose hasbeneficial effects on other purposes). Operationalmanagement problems are even more complex inwatersheds where two or more multipurpose proj-ects exist. In this case, decisions for each projectmust be coordinated so that the projects themselvesfunction in a complementary fashion.

Over the past decade, computer models that givethe project manager much greater flexibility thanpreviously used fixed operating rules have beendeveloped. Thus, it is now feasible to model theoperation of single projects or large systems of inter-connected projects.

Many fixed operational rules have been replacedby models that permit day-to-day decisionmakingthat can more effectively consider several objectivesof a project (or projects) simultaneously. Most ofthe current models include only hydrologic inputsand outputs, and the physical operation of a proj-ect or system. Economic, social, institutional, andenvironmental factors affecting operational man-agement are only considered indirectly, or evalu-ated outside the model. Despite their limitations,these models have the capacity to improve both

short- and long-term operational management deci-sions and plans.

More recently, modeling capabilities for opera-tional management of streamflow regulation struc-tures have expanded to include mathematical op-timization models and—in a few instances—online,real-time models used for controlling major por-tions of a system’s operation. Some simulationmodels have also been expanded to analyze eco-nomic, institutional, and environmental factors.However, data acquisition (particularly for real-time operation) and model calibration are substan-tial obstacles to widespread use of the models cur-rently available for large systems; many operatingentities do not have sufficient computer capabilitiesand personnel to use the most sophisticated modelsavailable for onsite operational decisions.

Instream Needs

Determining instream flow needs differs fromother water availability problems in that instreamflow needs are frequently linked to water qualityrather than water quantity requirements. The twomost common purposes for establishing instreamflow requirements are to preserve and protectaquatic and riparian ecosystems, and to complywith statutory, contractual, or institutional obliga-tions to maintain the necessary streamflows.

The common practice of specifying instreamneeds in terms of water volume dates back to theearliest days of water resource development in thiscountry, when allocating water to meet these needswas labeled ‘‘low-flow augmentation. While it wasrecognized that many of the objectives of low-flowaugmentation were related to water quality char-acteristics rather than to water quantity per se, vir-tually all of the analytic techniques available forplanning and managing strearnflow regulation werequantity oriented,

In the mid-1960’s, knowledge of water quantity/water quality relationships and computer model-ing capabilities simultaneously reached the pointwhere it became possible to model many importantwater quality characteristics in reservoirs andstreams. The first such models dealt with the twobest understood quality characteristics—tempera-ture and dissolved oxygen. These two characteris-

128 ● Use of Models for Water Resources Management, Planning, and Policy— — — —

tics were considered to be particularly importantbecause they are involved in virtually all physical,chemical and biological processes occurring instreams.

By the early 1970’s existing models were capableof assisting planning efforts to meet instream needsbased on water quantity requirements, and provid-ing information for some policy and regulatory as-pects of instream-needs analysis. However, theavailable models could not, in most cases, produceresults commensurate with requirements for opera-tional management. New models that show prom-ise for meeting the requirements for managementdecisions have recently begun to appear.

The role of models in policy and regulation ofinstream flow is limited by a lack of knowledgeabout the qualities of instream flow required to en-sure the survival of fish, wildlife, and other aquaticand riparian biota. Many existing instream require-ments are based on extremely limited informationconcerning biological survival and tolerances. Mostexisting standards establish a single value for in-stream needs, so that in essence a pass-fail condi-tion exists. In policy and regulatory work, tradeoffsare critical components of analysis, and tradeoffanalysis is severely hampered when degrees of suc-cess and failure cannot be analyzed. Improved un-derstanding of relationships between instream flowand biotic life would greatly enhance the utility ofexisting models in policy and regulatory areas.

Water Use Issues

Domestic Water Supply

Domestic water suppliers in this country usual-ly assume a utility responsibility —i.e., that of aregulated monopoly— in their service area. In ef-fect, they agree to provide services to all users withinthe service area according to an established ratestructure, and to assure, insofar as possible, thatthe service is equally available and dependable forall users. This does not preclude the possibility ofestablishing service classes or priorities for variouscategories of users (e. g., differentiating betweenpurely domestic use and industrial use), but suchpractices are much less common in the water supplyindustry than in the electric power industry. Be-cause of this ‘ ‘utility’ philosophy, water agencies

have traditionally worked much harder to secureadditional supplies than to control or managedemands.

In many instances, domestic water use projec-tions have consisted solely of projecting changes inpopulation and applying established per capita de-mand factors to the projected future population.In some cases projections have been somewhatmore sophisticated. Some analysts recognize thatper capita consumption is affected by changes indemography, technology, and lifestyles, and at-tempt to adjust current per capita consumptionestimates to reflect anticipated changes in these fac-tors. However, only a modest amount of data isavailable on which to base such adjustments.

As growth in domestic demands and competinguses diminish the relative availability of water,water utilities will have to develop and evaluate al-ternatives for obtaining additional supplies, or strat-egies for allocating available supplies among com-peting users. Models can be used to establish pric-ing policies, user priorities, and other economic andtechnological aspects of system expansion. Modelscan also play a useful role in examining the likelyresponses of various sectors (domestic, commercial,municipal, and industrial) to strategies that mightbe used to achieve targetted reductions in use.

If priority use and pricing systems come intowidespread use, models will be needed to assist indetermining the conditions under which use priori-ties should be implemented, and the amounts ofwater that should be made available to each userclass.

When additional supply capacity is deemed nec-essary, models can be used for planning efforts todevelop and expand water distribution systems.These models focus primarily on the hydraulics andeconomics of the distribution system itself ratherthan on water use characteristics.

Irrigated Agriculture

Model use in the area of irrigated agriculture hasa relatively long history, and has grown more rapid-ly and is more widespread than for other water uses.Since irrigation occurs primarily where rainfall isdeficient, farmers have had to be more consciousof the importance of water and of the need to man-

Ch. 6—Modeling and Water Resource Issues 129

age a limited supply. Uses of models have rangedfrom determining the need for irrigation water andtiming applications for specific crops, to develop-ing policies for allocating water among users intimes of water shortage. Models are also used toplan, design, and operate water distribution systemsfor large irrigation projects.

Some of the models available for planning andoperational management of irrigation water are ex-tremely sophisticated. They enable users to con-sider water requirements of individual crops overan entire growing season or for specific intervalswithin the growing season. The models can alsogage the effect of precipitation on the amount andtiming of needed irrigation water. Some of the mostsophisticated models permit users to consider op-tions to defer applying water or to reduce theamounts of water applied during periods of watershortage. These models provide information on therisks of crop failure or the likelihood of reduced cropyields, thereby helping farmers to apportion limitedsupplies among various crops. Such models alsoprovide information on the economic consequencesof buying and selling water entitlements.

The availability of these models to farmers in-volved in irrigated agriculture will be even moreimportant in the future, as competition between ir-rigation and other nonagricultural water uses in-creases in the Western States.

Other Offstream Uses

Water is also used for such purposes as coolingin thermal electric power-generating plants; proc-ess water and cooling in coal gasification, shale oilproduction and other energy extraction and conver-sion processes; hydraulic mining; and for use as atransport medium in slurry pipelines. Many ofthese uses require withdrawals of large quantitiesof water from rivers and streams. In some cases(e. g., evaporative cooling, slurry pipelines, and in-terbasin transfer) not only are the withdrawalslarge, but the use is “consumptive’ ‘—i.e., the waterwithdrawn is lost from the stream system fromwhich it was withdrawn. In other cases (e. g., once-through cooling, mineral extraction, and energyconversion), while withdrawals are relatively large,the use is not consumptive because the water even-tually returns to the stream after use. In some of

these cases, however, the quality of the returnedwater is substantially altered and the water may notbe fit for many other uses.

Models are currently available to assess the ef-fects of offstream uses on water quantity and toassess such common water quality characteristicsas temperature and dissolved oxygen changes.However, improvements in models are needed forassessing the economic and environmental implica-tions of water withdrawals and potential water qual-ity changes due to offstream uses.

Policy and regulatory functions are greatly af-fected by the lack of adequate modeling capabilityin this problem area. The volume of some proposedoffstream uses—e. g., coal gasification or liquefac-tion and oil shale processing—is so large that deci-sions regarding them are likely to affect the econ-omies and ecologies of large regions and involvea considerable number of governmental jurisdic-tions. Information from models would be of greatvalue in resolving the controversies and inter-jurisdictional disputes that will inevitably arise.

Efficiency and Conservation

Models for dealing with water use efficiency andconservation are considerably different from modelsused in other aspects of water management. Withthe exception of irrigated agriculture, water usersin this country have not emphasized efficiency andconservation except during periods of critical watershortages. Consequently, there is no substantialbody of knowledge regarding efficiency and con-servation strategies and their economic, social, andenvironmental consequences. Some data exist onspecific conservation practices and their effects inisolated pilot programs under ‘ ‘normal’ conditions,and some data exist on a wide range of conserva-tion practices and effects under emergency condi-tions. However, it is doubtful that the existing database and knowledge (other than for irrigated agri-culture) provides a sufficient basis for developingthe models needed for policy and planning func-tions.

Pertinent economic models—e, g., models to de-termine the effects of water pricing on use—arediscussed in “Social and Economic Models” of thischapter.


Evaluation of Currently AvailableSurface Water Flow and

Supply Models

model applications; for example, under the issueof ‘flood forecasting and control, the capabilitiesof models vary for the seven applications addressed.Models are rated from A to F, with A indicatingthat modeling for this purpose does a good job in

Table 7 presents evaluations of currently avail- supplying the needed information, and F indicatingable surface water flow and supply models. Each that the state of the modeling art for this purposewater resource issue is subdivided into specific is generally unsatisfactory.

Table 7.—Surface Water Flow and Supply Model Evaluation

OverallIssue Information required for applications rating

Water avaiiabiiity:1. Flood forecasting and control

2. Drought and low-flow riverforecasting

3. Streamflow regulation(including reservoirs)

4. Instream flow needs:Fish and Wildlife

Recreation

Navigation

Hydroelectricity

Water use:5. Domestic water supply

6. Irrigated agriculture

7. Other off stream uses

8. Water use efficiency

a. Flood peaks for channel and bridge designb. Flood hydrography for reservoir design and operationc. Simultaneous flood hydrography for flood control system design and operationd. Flood depth mapping for flood plain land-use planninge. Effects of land use on downstream flows for upstream land-use planningf. Flood peaks after dam failures for emergency preparedness planningg. Soil moisture conditions for land drainage design

a. Low river flows for off stream usesb. Timing of drought sequences for estimating cumulative economic impactc. Soil moisture conditions for precipitation-supplied uses

a. Runoff volume for maximum obtainable yieldb. Runoff time patterns (within and among years) for reservoir sizingc. Simultaneous runoff volumes in regional streams for regional

water supply planning

a. Low river flows for estimating fish support potentialb. Within-year timing of low flows for fish Iifecycle matchingc. Timing of drought sequences for estimating minimum reservoir or lake levelsd. Flow velocities within streams for estimating effects on fish speciesa. Low river flows for sustaining recreation capacity and esthetic appealb. Timing of flow sequences for matching with recreation periodsc. Runoff time patterns (within and among years) for estimating the impact of

fluctuations in lake levelsa. Low river flows for determining waterway capacityb. High river flows for determining navigation interferencec. Formation of surface ice for determining navigation interferencea. Timing of flow sequences for estimating run-of-the-river

generating capacityb. Runoff time patterns (within and among years) for designing

streamfiow regulationsc. Simultaneous runoff volumes in regional streams for regional generating

system planning

a. Timing of water use for delive~ system designb. Water pressures throughout delivery system for delivery system designc. Volume of use for sizing supply facilitiesd. Return flow volumes for designing wastewater collection systems

a. Timing of water use for delivery system designb. Volume of use for sizing supply facilitiesc. Return flow volumes for drainage system design

a. Volume of industrial use for sizing supply facilities

a. Effect of increased use-efficiency on return flows for evaluatingconservation measures

BccccDc

cBc

AB

c

cBBccB

BccD

B

B

c

DcBc

cBB

B

cRating Key:

A Modeling of the physical process at the current state-of-the-art does a good job in supplying the needed information.B Information between adequate and good.C Modeling does an adequate job for most purposes.D Information between unsatisfactory and adequate.F The supplied information is generally unsatisfactory.



SURFACE WATER QUALITY

Introduction

Billions of dollars are spent annually in theUnited States to protect the quality of surfacewaters. Unless carefully managed, residual wastesfrom municipalities, industry, and agriculture canseriously interfere with many beneficial water re-source uses. Water quality models are used exten-sively in Federal, State, and local efforts to main-tain and improve the quality of the Nation’s sur-face waters.

Water quality models serve two general func-tions. The first is to provide basic scientific insightand understanding about the relationships betweenmaterial inputs and water quality changes. Theserelationships are expressed in the form of mathe-matical equations that interrelate and synthesize ob-servations. The second function is of an engineer-ing nature. Once confidence in these relationshipsis obtained, the equations can be used to helpmanage, plan, and make policy. Given the presentstate of scientific knowledge and engineeringdevelopment, existing models can generally pro-vide a limited basis for water quality decision-making.

Mathematical models of water quality are mostfrequently used for planning, to some extent forpolicymaking, and to a lesser degree for day-to-dayoperations and management. Their most commonuse is to determine the degree of treatment requiredfor a specific wastewater discharge in order toachieve or maintain a desired receiving water quali -ty. Other uses include determining the magnitudeand effects of urban runoff, and assessing the ef-fectiveness of alternative measures for preventingsoil erosion and the resulting sedimentation withinwater bodies.

Because models simply quantify existing scientif-ic knowledge about water quality, a basic under-standing of the processes that underlie model equa-tions and assumptions is helpful in assessing modelcapabilities. The next section, ‘ ‘Types of ModelsUsed in Surface Water Quality Analysis, describesthe current state of scientific knowledge about deter-minants of water quality, and examines how wellthis knowledge is incorporated into present water

quality models. Later, the state of the art of waterquality modeling is discussed on an issue-by-issuebasis, analyzing 10 major problems under the gen-eral categories of point and nonpoint pollutionsources. The section entitled ‘‘Evaluation of Cur-rently Available Surface Water Quality Models’assesses currently available model types. Evalua-tions are made both according to the characteristicsof the models themselves, and for the 10 majorproblems to which they may be applied.

When considering water quality concerns, fourbasic questions face the analyst:

1. What is the quantiy and quality of the water andresiduals coming from each point and non-point source?

2. How are these materials transported to thereceiving waters?

3. How are these wastes transported within thereceiving water?

4. What processes transform waste residuals with-in a water body?

Given the response of the system, the analystmust further consider the following quest ions:

●

●

●

●

What deleterious effects do these wastes haveon beneficial uses?Do existing standards reflect the magnitudeof the effects?What control alternatives are available, howwell do they perform, and how much do theycost?Are these control alternatives politically, eco-nomically, and esthetically feasible?

All of the above information is needed for man-agement, planning, and policy decisions. Modelsare available, in varying degrees of detail and ac-curacy, to help the analyst address each of thesequestions.

The common basis for the majority of water qual-ity models is the principle of ‘‘mass balance.Water and any material inputs from natural or hu-man sources are followed: 1 ) from their point oforigin; 2) as they travel to the water body; and3) as they travel within the water body. The modelsaccount for biological, physical, and biochemical


reactions that occur, and additions of water or ma-terials.

To run these models, users must provide quanti-tative estimates of the characteristics of the water-shed and the receiving water body. Source quanti-ties, constituents, and other pertinent characteristicsmust be enumerated, and the numerical coefficientsthat describe the above reactions must be known.

Water quality models have one aspect that is botha vice and a virtue—most provide an absolute nu-merical value for any given variable such as the con-centration of a pollutant. While it is desirable tohave such a number, often no indication of thepossible error is given. In practice, most waterquality projections are subject to large errors andmust be validated with field observations.

However, water quality models are still very use-ful in planning contexts, for example, because rel-ative effects of control alternatives can be analyzedwith sufficient confidence for many purposes. Mod-el projections, when combined with the professionaljudgment of water resource analysts, are often thebest information available to aid the decisionmakerin evaluating alternatives.

Types of Models Used in SurfaceWater Quality Analysis

All water bodies are affected by inputs from nat-ural sources and human activities. The accuracywith which models can estimate relationships be-tween these inputs and the water quality responsedetermines their utility for management, planning,and policy purposes. Thus, current levels of scien-tific and engineering knowledge about these rela-tionships form the basis for assessing surface waterquality models.

Water quality models can be divided into threecomponents that describe:

● source of materials;● transport to and within the receiving water;

and● processes occurring within the receiving water;

The first component estimates the inputs of sub-stances through human activities and natural phe-nomena; the second, the hydrologic and hydro-

dynamic regime of the water body and its water-shed; and the last, the biological, chemical, andphysical processes that affect water quality.

Source of Materials

Water bodies may receive point source dischargesfrom municipal, industrial, and agricultural activ-ities; dispersed or nonpoint source runoff from thesesame areas; natural inputs from undisturbed water-sheds; and additional chemicals from rainfall.

The chemical characteristics of effluents frommunicipal sources are well known with respect toboth average values and their variations. This isalso true for many industries that generally pro-duce one or a few products, such as the pulp andpaper, canning, and steel industries. However, in-dustries that produce a variety of products, suchas organics, synthetic chemicals, and pharmaceuti-cals, produce discharges that are more difficult tocharacterize.

Information on agricultural and feedlot sourcesof waste is meager, but has been improving in re-cent years. Irrigation return waters pose difficultproblems, particularly in the mid- and far-westernregions of the country where high background con-centrations of salts of natural origin prevail. Thetime-variable nature of return flows, which are bothpoint and distributed, introduces additional com-plexities. Our social and scientific awareness ofthese problems is relatively recent; consequently,the historical data on these sources are minimal,and many gaps remain in current knowledge of thegoverning phenomena.

The ability to quantify pollutant loadings froma variety of sources is critical, particularly withrespect to differentiating between point sources,which are readily controllable, and nonpointsources, which are relatively difficult to identify andcontrol. Assigning realistic values to distributednonpoint sources is very difficult, given the pres-ent state of knowledge and data, Current modelsprovide at least some assessment of the problem.

The most significant information gap lies inquantifying toxic substances from nonpoint sourcesor from residues of toxic materials created by pastactivities, e.g., from riverbeds and from landfillsthat leach into water systems.


Transport to and Within Receiving Waters

Point discharges are transported by pipes, openchannels, or other conveyance devices from thepoint of origin to the receiving water on a regularbasis. Nonpoint discharges move through stormdrainage systems, via overland flow, and throughsubsurface flow to the receiving water as a resultof rain events. Consequently, the quantities ofmaterials entering water bodies from nonpointsources are much more difficult to predict.

Most surface water quality models include a sur-face water flow submodel as part of the program,since in most cases it is necessary to predict runoffand flow quantities before making quality estimates.Many of the models discussed in the previous sec-tion on surface water flow are used as componentsof surface water quality models.

Pollutant transport by rivers and streams is, ingeneral, better understood than transport withinlakes. Transport in streams depends primarily onflowing water; within lakes, and some complex riversystems, movement of pollutants occurs by diffu-sion and dispersion as well—difficult processes tomodel. In addition, a longer and more extensivedata base is available for streams than for lakes.

Transport in streams can be approximated bysimple one-dimensional models—the one dimen-sion being the direction of flow. Under certain con-ditions, simple models can adequately simulatetransport in lakes, but often more complex two- andthree-dimensional models are necessary. The stateof knowledge and computational techniques aresuch that only the most proficient analysts can usethese models.

The above remarks apply to situations that arenot highly time dependent. When water qualityanalysis must incorporate such factors as stormsurges from combined sewers or rapidly changingriver flows, the models must be considerably morecomplex. These models are still in the developmen-tal stage and their results are only marginally usefulat present.

Processes Occurring Withinthe Receiving Water

In general, the chemical, physical, and biologicalprocesses of rivers and streams are better modeled

than those of lakes. In addition, more extensive wa-ter quality data exist for rivers and streams, par-ticularly for such constituents as dissolved oxygenand coliforms (bacteria used to indicate the pres-ence of sewage).

Eutrophication (excess algae or aquatic weedgrowth) is another widespread problem. The nutri-ents that cause eutrophication originate from a vari-ety of municipal, industrial, agricultural, and natu-ral sources. While the state of the art permits somemodel-based assessment, data requirements are soextensive that these techniques are often imprac-tical. Simplified approaches, involving the nutrientsphosphorus and nitrogen, presently yield resultsthat may be indicative and, in certain cases, ade-quate for the intended purpose.

For inorganic and organic chemical water qual-ity, the present state of knowledge is mixed. Thebiochemical reactions of certain industrial chemicalsare sufficiently understood to permit the develop-ment of reliable models. This is true for a widerange of chemical compounds of relatively simplestructure, which are commonly present in industrialeffluents and which are susceptible to the present-ly available treatment processes. While the reac-tions involving metals are not as well understoodas those of the simple industrial chemicals, theyhave been developed to a degree that will permitat least a marginal analysis and projection.

On the other hand, for more complex com-pounds, many of synthetic composition, far less isknown about reactions, byproducts, and removalby present treatment techniques. These substances,which inciude many toxic materials, may be mod-eled with simplifying assumptions, yielding reason-able projections in limited cases. However, on thewhole, current methods of analysis are regarded as

only marginally reliable, A similar assessment ap-plies to complex metals when concentrations ap-proach or exceed toxic limits. Water quality modelsthat analyze these substances are presently beingdeveloped.

A second area of notable uncertainty is the accu-mulation of toxicants in the food chain leading tofish. Much research has been undertaken over thepast decade to advance basic understanding of theproblem, collect data, and develop models, someof which appear to be very promising. Preliminary

134 ● Use of Models for Water Resources Management, Planning, and Policy—— .—

Photo credits: @ Ted Spiegei, 1982

Researchers are exploring natural capabilities to reduce nutrient levels in effluent flows as a potential means of tertiarysewage treatment. At left, water in a meandering stream is cleansed through contact with vegetation and reaeratedon its way to the Hudson River; at right, a Florida cypress dome is fertilized with the nutrients in partially treatedeffluents from a 150-unit mobile home park. Models are available to estimate the effectiveness of various treatmentmethods in removing such nutrients as phosphorus and nitrogen, and to assess the effects of nutrients on biological

processes in lakes and streams

food chain and fisheries models are available; how-ever, these are in a relatively primitive state. Al-though they may provide some insight and under-standing, they are neither sufficiently calibrated noradequately validated for management purposes.

The same may be said for aquatic ecosystemmodels that describe changes to aquatic plant andanimal populations subjected to water qualitystresses. Ecosystem theory-the basis for such mod-els—is still in a developmental stage. However, theresults of laboratory studies on the effects of specificpollutants on sensitive organisms have been incor-porated into water quality models with some suc-cess.

Nonpoint Source Issues

Urban Runoff

Urban runoff (along with agricultural runoff) isone of the most difficult waste discharges to con-

trol because of its intermittent nature and varyingquality. Federally mandated control and manage-ment of urban runoff has created the potential forincreased use of urban runoff models.

At present, urban runoff models are most helpfulin planning, primarily for water quality manage-ment and comprehensive areawide planning. Thebest examples lie in the section 208 programs ofthe Clean Water Act—particularly the Nationwide

—

Ch. 6—Mode/ing and Water Resource Issues 135

Urban Runoff Program. Such planning is designedto provide each State and the Environmental Pro-tection Agency (EPA) with information on pointsource and nonpoint (including urban runoff) treat-ment needs and the effectiveness of treatment meth-ods. Urban runoff models such as EPA’s Storm-water Management Model and the Corps of En-gineers’ STORM can simulate the quantity andquality of runoff from a specified runoff area andcan be used to compare the effectiveness of alter-native control strategies. These models may alsobe linked to receiving water models to gage the ef-fects of urban runoff on receiving water quality.

Urban runoff models can also play an importantrole in Federal and State agency policy decisions.Federal agency construction grants allocations, andrequests for such funds by State agencies, could bebased in part on estimates of the volume and quality

of point source and nonpoint source wastes in aspecific area, the effects of these wastes on thereceiving water, and the effectiveness of nonpointsource control in alleviating the problem.

Urban runoff models do not appear to have at-tained the credibility necessary to be used as regu-latory tools at this time. These models require anextensive local data base, and such information isusually unavailable, except for cities in which spe-cific studies have been performed to develop, cali-brate, and test such models.

Erosion and Sedimentation

Models of erosion and sedimentation are devel-oped primarily by such Federal agencies as theCorps of Engineers, the Soil Conservation Service,the U.S. Geological Survey, and, to a lesser extent,

Photo credit: U.S. Department of Agriculture

Two years of low rainfall on the Big Canyon Ranch near Sanderson, Tex., greatly reduced plant cover levels, settingthe stage for extremely high runoff rates on the draw pictured above after rainstorms hit an area 30 miles away. Plantcover is a major determinant of soils’ abilities to absorb moisture and resist erosion; runoff and erosion models consider

cover levels as one of many factors in estimating flows and sediment transport

136 ● Use of Models for Water Resources Management, P/arming, and Policy

EPA. Extensive use is made of erosion and sedi-mentation models by Federal, State, and local agen-cies concerned with river management. Construc-tion agencies use these models to assist in opera-tional management, e.g., in dredging navigationchannels and operating reservoirs. Sedimentationis a critical factor in reservoir management, as itcan reduce a reservoir’s useful volume. Riverauthorities must have information on rates ofsedimentation and ways of alleviating or mini-mizing sedimentation to operate their reservoirsmost efficiently.

Local, State, and Federal agencies concernedwith forestlands, rangelands, and farmland man-agement continually seek better ways to minimizesoil erosion. They employ models to guide the selec-tion of effective management techniques.

A primary concern is the large amounts of nu-trients (especially nitrogen and phosphorus) con-tained in eroded soils. Soils reaching waterwaysmay impart those nutrients to the water, potentiallycausing nuisance algal growths or other symptomsof eutrophication.

Probably the greatest utility of erosion and sedi-mentation models lies in the area of planning. Forexample, the Corps of Engineers employs suchmodels to plan and design erosion control struc-tures along rivers and coastal areas and to estimatethe extent of sediment accumulation over the lifeof a reservoir. The Soil Conservation Service useserosion models to plan erosion control programson farmlands and forestlands.

Because toxic chemicals often adhere to riversediments, sediment transport models are used topredict the movement and fate of toxicants accident-ally released into waterways. EPA relies on waterquality models incorporating sediment transportsubmodels to follow the transport of Kepone downthe James River to the Chesapeake Bay. The agen-cy is using this information to plan monitoring pro-grams and subsequent mitigation programs, ifneeded.

Salinity

Several factors may cause the buildup of excesssalinity in surface waters. One major source is irri-gation return flows. To maintain a favorable salt

balance in agricultural soils, farmers may apply

more water to their crops than is required for plantproduction. The additional water leaches out ex-cess soil salts that may either flow overland to sur-face waters or percolate to the ground water. Theerosion of soils with high salt contents, such as themarine shales found extensively in the West, andthe input of salts from natural sources, such asbrines, also contribute to excess salinity. Finally,the concentration of salt in surface waters can in-crease due to evaporation, reductions or diversionsin flow, and plant transpiration.

Salinity, as a physical process, is one of the bestunderstood pollution problems, and relatively easyto model, Many models exist to predict salt concen-trations in agricultural drainage as a function ofcrop, soil type, and irrigation practice; downstreamsalinity concentrations; and the effects of excesssalinity on crops, metal deterioration, soap con-sumption, and health. A well-developed data basecomplements these models.

Models are widely used to develop managementstrategies for salinity control. They can providemanagers with information on the effectiveness ofcontrol options for reducing downstream salt con-centrations. In addition, these models are usefulfor evaluating the likely effects of proposed regula-tions. From a planning standpoint, these samemodels are used to develop areawide salinity con-trol plans and can aid in setting funding prioritiesto implement these plans.

In the ares of policy, salinity is an importantaspect of international water rights issues and treatyobligations between the United States and Mex-ico. In particular, the salinity of the Colorado Riverhas been a major international issue for some years.The increase in salinity of the Colorado from salinereturn flows before it leaves the United States isa major problem for water users in Mexico. Modelshave been used to determine whether planned con-sumptive uses from the Colorado Basin will allowthe United States to meet its treaty obligations fordelivering water at or below a specified salinity.

Agricultural Pollutants

Agricultural pollutants are found in runoff fromirrigated and nonirrigated agricultural lands andpastures. The pollutants include soil particles


eroded from the land; organic substances fromdecaying vegetation, animals, and feedlot waste;nitrogen and phosphorus from commercially pro-duced fertilizers as well as from animal waste; andpesticides that have been applied but are not yetdegraded. These pollutants find their way into near-by receiving streams, where their effects must beassessed.

Agricultural pollutants are generally consideredto originate from nonpoint sources; animal feedlots, however, are considered point sources. Likeother point sources, the latter must be treated tomeet effluent and receiving water standards accord-ing to sections 301 and 303 of the Clean Water Act.Nonpoint sources are eventually to be controlledas well, but standards and guidelines for imple-menting controls have not yet been promulgated.

Mathematical models aid in assessing the in-stream effects of these point and nonpoint sources—such analyses play an important role in regulatingpollution sources. The models for tracking organicmaterials and their effects on oxygen resources instreams are well developed, well documented, andeasily usable by personnel with appropriate analyti-cal skills and knowledge of water quality manage-ment principles. Such models should also withstandthe scrutiny of litigation. Models for nutrients andpesticides, however, are not used as broadly asmodels that predict levels of dissolved oxygen.

Mathematical modeling of agricultural pollutantsfinds extensive use in planning. Models have beenused primarily for section 208 studies of areawidepollutant problems and water treatment needs.Such studies enable States and EPA to establishpriorities for treatment, based on estimates of theeffects of point and nonpoint sources on receivingwaters.

Not only do Federal and State agencies use math-ematical models for the kind of planning mentionedabove, but they also use these models to determinethe effectiveness of treating agricultural pollutants,recommend funding levels to Congress, and pro-pose legislation for controlling agriculturalpollutants. In these cases, mathematical modelsmay be the only means of linking the pollutionsource to effects on the receiving waters—a con-nection that is important in estimating the benefitsof regulatory programs.

i


Agriculture can also serve as a means of treating certainwater pollutants. Lubbock, Tex., utilizes a 3,000-acre farmas its tertiary disposal facility, employing nutrient-laden

waters to irrigate and fertilize crops

Airborne PollutantsSince the enactment of the 1971 Clean Air Act,

mathematical models have been used as regulatory

tools by Federal and State agencies that are assignedresponsibility for air pollution enforcement. Suchmodels determine the relationship between dis-charge and downwind exposure concentrations ofcommon air pollutants such as sulfur oxides, nitro-gen oxides, and particulate. Some of these pollut-ants are transferred from the air medium to waterand thus contribute to water pollution. Such materi-ah include windblown dust, hazardous substances,and compounds that may eventually produce acidprecipitation.

The transfer of pollutants from air to water hasreceived increasing attention in the last few years.


Hazardous substances in incinerator effluents andwindblown erosion from landfill sites are problemsfor which mathematical models may be used to an-ticipate and formulate control strategies. Modelsof short-range pollution transport (less than 200km) are currently available. The potential conse-quences of acid precipitation, and of the deposi-tion of heavy metals, radioactivity and other haz-ardous materials from powerplant air emissions,may require Federal and State agencies to assessfuture water quality problems resulting from in-creased energy production. Models of long-distancepollution transport, and of atmospheric processesthat may produce acid rain, are in early stages ofdevelopment.

Point Source and General Issues

Wasteload Allocation (Point Source)

Wasteload allocation refers to the process ofdetermining the amount of some waste material thata particular discharger is allowed to release by ana-lyzing the relationship between discharged amountsand resulting concentrations in the receiving water.This cause-effect relationship may be determinedafter the fact through sampling programs, or beforedischarges occur with the help of mathematicalmodels.

Water quality models find their most appropriateregulatory roles in estimating waste treatment needsfor compliance with the Clean Water Act. The actsets forth two criteria for water quality standards:1) effluent requirements for regulating ‘ ‘end-of-pipe” discharges, as specified in section 301 of theact; and 2) receiving water standards, as specifiedin section 303 of the act. Discharges who meet ef-fluent standards may be required to provide fur-ther treatment if resulting waste discharges causehigher-than-acceptable receiving water concentra-tions. Wasteload allocation models determine themaximum allowable level of discharge for individ-ual producers in order for pollutant concentrationlevels in receiving waters to be at or below existingstandards. Removal techniques to meet these limitscan then be selected.

Mathematical models for this procedure are welldeveloped and documented, can be adapted to re-ceiving waters of different types, can be easily usedby regulatory staff, and are reliable enough to with-

stand judicial scrutiny. Waste allocation is par-ticularly complex, however, when a number ofdischarges reach a common receiving water nearthe same point. In such cases, the allowablewasteload can again be determined by a mathemat-ical model, but assigning wasteloads equitablyamong the contributors must be a legal and admin-istrative decision.

Water quality models have been used extensivelyin planning for treatment needs throughout the Na-tion. As part of section 208 of the Clean Water Act,point and nonpoint wasteloads were to be deter-mined for segments of the Nation’s waterways.Mathematical models were used in these cases, firstto estimate current loadings from the point andnonpoint sources, and then to estimate the impactof these loadings on the receiving stream. Basedon the magnitude of these effects, the need forwasteload reduction was determined. Then, basedon the ratio of point source to nonpoint source dis-charges, Federal and State agencies could estimatewhere the greatest water quality improvement couldbe achieved at the least cost.

Probably the most dramatic and exemplary pol-icy-level application of these water resource modelswas undertaken by the National Commission onWater Quality. The commission, mandated byCongress as part of the 1972 Federal Water Pollu-tion Control Act Amendments (Public Law 92-500), undertook a number of assessments of thesocial, economic, technical, and environmental im-pacts of implementing the other sections of the act.Among the commission’s responsibilities were a setof water quality studies to evaluate the act’s im-pact on some 40 specific areas around the UnitedStates. Water quality models were used extensive-ly in these studies and were, in fact, necessary tocarry them out. Study results indicated that the ef-fluent regulations of the 1972 act should be alteredto reflect more realistically attainable levels of treat-ment in the allotted time periods. The work of thecommission contributed to policy changes withinEPA, and influenced congressional formulation andpassage of the 1977 Clean Water Act (Public Law95-21 7), which incorporated many of the commis-sion’s recommendations.

Wasteload allocation models were critical to thecommission’s ability to demonstrate the conse-quences for the Nation’s receiving water quality of


Photo credit: EPA-DOCUMERICA, Doug Wilson

Untreated water from a pulpmill in Puget Sound, Wash.

implementing the 1972 act. The study also revealedsome shortcomings in then-current modeling capa-bilities, however. Contractors performing work forthe commission relied primarily on dissolved solidsand dissolved oxygen models; models for nutrientsand toxic materials were applied in only a few situa-tions, largely because existing data bases were in-adequate for calibrating and validating them.

Thermal Pollution

Thermal effluents are among those regulated bythe Clean Water Act. Effluent limits have been setfor thermal wastes as well as for allowable temper-ature increases in receiving waters. Zones of influ-ence and resulting temperature increases from ther-mal effluents can either be monitored directly orpredicted with mathematical models.

Mathematical models for thermal wastes rangefrom fairly simple one-dimensional models to morecomplex two- and three-dimensional models. Mostof these models have been developed through thesupport of EPA and the electric utility industry andhave been applied in many locations. Most regula-tory staffs can operate the simpler thermal wastemodels, but the more complex multidimensionalmodels require well-trained staff.

The electric utility industry uses mathematicalmodels extensively in applying for construction andoperation permits for nuclear powerplants throughthe Nuclear Regulatory Commission, and in pre-paring environmental impact statements as re-quired by the National Environmental Poiicy Actof 1969. Under the latter act, the permittee mustshow the extent of the environmental impact of its


facility, in particular the impact of the thermalwaste. Such effects are routinely forecasted by usingmathematical models.

Toxic Materials

Compounds that cause some injury to humansor other organisms of concern are classified as toxicmaterials. Such materials are not necessarily lethal,but may be compounds that produce such sublethaleffects as cancer, birth defects, or reproductivefailure.

Toxic materials are regulated under several stat-utes, including the Clean Water Act, the ToxicSubstances Control Act of 1976 (Public Law94-469), the Resource Conservation and RecoveryAct of 1976 (Public Law 94-580), and the SafeDrinking Water Act of 1974 (Public Law 93-523).Regulation under this last act is discussed in thesection entitled “Ground Water Quantity andQuality. ” Although control is focused on technol-ogy-based standards, mathematical models havepotential roles in enforcing portions of these acts.As with other pollutants, effluent requirements havebeen established for point sources based primarilyon removal techniques. However, receiving watercriteria must be met as well. Modeling for toxicmaterial concentrations may be required at somefuture time to determine further treatment needsif receiving water standards are not being met.

While legislation exists for control of nonpointsource toxicants, implementation has been givenlow priority. As controls are applied, however,ground and surface water quality models could playan important role in determining the cost effec-tiveness of alternative control measures, Mathemat-ical models can also be used to design monitoringnetworks so that stations can be best located andsampled to gain maximum information from moni-tormg.

As with other issues, mathematical models fortoxic materials have greatest utility in the planningprocess. Models can be used to anticipate problems,and to test different management approaches forremoval effectiveness and managerial efficiency.Since regulations for controlling liquid and gaseoussources of toxic substances are currently being im-plemented, and those for hazardous solid wasteshave recently been issued, models for planning

long-term toxic material control should find wide-spread application.

Drinking Water Supply

The Safe Drinking Water Act is the principalFederal legislation regulating the quality of drink-ing water. It, along with State statutes and localordinances, regulates the quality of public drink-ing water. Regulations apply to water quality atthe end of the treatment process; consequently,streamwater quality models have no roles per sein regulating drinking water under this act. How-ever, toxicology models, which relate concentrationsof various hazardous substances to human healthrisks, are used to aid in setting standards. Thesemodels use differing methods for extrapolating datafrom animals to humans, so that resulting estimatesof human risk may diverge widely. The OTA re-port, Technologies for Determining Cancer Risks Fromthe Environment, provides an assessment of toxicologymodels.

The quality of the raw water is an important fac-tor in supplying high-quality water for human con-sumption. Where raw waters are degraded by up-stream users, water quality models can be used topredict water quality at the point of intake to deter-mine the level of treatment needed. In particular,water quality models are used in determining whenintakes should be closed due to contaminants origi-nating upstream. For example, a spill of carbon tet-rachloride in the Ohio River several years agoforced water users downstream to close intake struc-tures at appropriate times to avoid contaminatingthe water supply. Models were used to predict whenand how long the carbon tetrachloride would be inthe vicinity of the intake structures.

Water Quality Impacts on Aquatic Life

Models for predicting water quality impacts onaquatic life involve two steps: 1 ) estimating concen-trations of those materials that may affect aquaticlife (positively or negatively), and 2) comparingcalculated concentrations with accepted criteria tojudge the consequences of those concentrations tothe ecosystem. This latter step is seldom incor-porated into the model structure, and requires pro-fessional judgment by aquatic ecologists.


The models used to assess impacts can vary fromvery simple models for calculating the effects of con-centrations of selected materials, to very complexmodels incorporating several different types ofpollutants and their effects on numerous organisms.The complex models are the least reliable, due tothe lack of data to support many of the necessaryassumptions and the great difficulty in calibratingand validating them. Both types of models requireconsiderable professional judgment in applying theresults to field situations.

Models to determine water quality impacts onaquatic life are primarily of value in the planningprocess. This is due to the kinds of applications thatcan be made of these models, the current state oftheir development, and the number of areas forwhich data are adequate to apply them.

Aquatic life impact models can be usefully ap-plied if a theoretical analysis of the aquatic systemis coupled with coefficients derived from controlledlaboratory experiments. Examples include modelsof the movement and effects of Kepone in the JamesRiver, of polychlorinated biphenyl (PCBS) in theHudson River, and of PCBS in the Great Lakes.Both the Kepone and PCB models facilitate impactassessment by allowing researchers to compare ex-posure concentrations to tolerable levels, while theP(2B models can predict alterations in populationsif toxic interactions are included. These modelshave been used to forecast the effectiveness of alter-native remedial actions, and thus help provide abasis for future regulatory activities.

Evaluation of Currently AvailableSurface Water Quality Models

A model’s level of complexity and its degree ofavailability provide the basis for a simple schemeof classification. Accordingly, four generic types ofmodels are outlined below, and their basic capabil-ities are summarized. In the evaluation table (table8), these four generic model types are rated accord-ing to their utility in analyzing five major aspectsof each of the 10 issue areas discussed above. Theevaluation table also assigns an overall rating formodeling sophistication in each issue area. Usinga potential scale of zero to 10, actual assignedratings range between 1 and 9, indicating the

uneven level of current modeling capability for sur-face water quality analysis.

Type Z is a standardized procedure or techniquethat may be routinely performed without a com-puter. It involves simple mathematical equations,statistical techniques, and graphical procedures. Ex-amples include use of the Streeter-Phelps streammodel for evaluating dissolved oxygen down-stream of point sources (although this is often pro-gramed into complex models), and evaluating lakeeutrophication potential with diagrams or regres-sion equations. While the procedure does not in-volve a computer, it is not necessarily unsophisti-cated. On the contrary, some ‘‘desktop’ proce-dures are mathematically quite sophisticated,whereas some complex digital computer models arenothing more than a programed version of intui-tion. Finally, a Type I model may still require con-siderable time and effort and the use of computa-tional aids (e. g., hand calculators) to be fully oper-ational.

Type II is a computerized version of a Type Imodel. This may avoid the tedium of routine calcu-lations and greatly expand the amount of data thatcan be processed. The level of complexity of theanalytical technique, however, is still low.

Type III is a procedure that is sufficiently com-plex that a computer is required for its use. Suchmodels generate numerical solutions for sets ofmathematical equations that could not be solvedprior to the advent of modern computers. Manyindividuals, consultants, universities, industries,and public agencies have constructed such models.

Type IV is the same as a Type III model exceptthat it is termed operational, meaning: 1) documen-tation (e. g., user’s manual, description, and theory)is available; 2) the program has been well testedand its credibility established by groups other thanthe model developer; 3) the program is availableand accessible to interested users (this does not pre-clude proprietary models); and 4) user support isavailable either from the model developer or fromother groups. Although several hundred large waterquality models are described in the literature, less

than 100 can be termed operational. A Type IVmodel can thus be used by others with relative ease.


Table 8.—Surface Water Quality Modei Evacuation

Generic type

IvI II Ill Computer, Overall level

No computer, Computer, Computer, complex,Issue

of modelingnot complex not complex comDlex operational sophistication

Nonpolnt source pollution and land useUrban runoff:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Erosion and sedimentation:Sourcelgeneratlon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Salinity:Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Other agricultural runoff:Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Airborne pollutants:Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Water quality (other than nonpoint sources and land use)Wasteioad allocation:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Thermai poiiution:Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Toxic materiais:Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport to receiving water. . . . . . . . . . . . . . . . . . . . .Transport in receiving water. . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Drinking water quaiity:Source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Water quality impacts on aquatic iife. . . . . . . . . . . . . . .Key: A Reliable, credibie modeling may bereadily used for most problems ofthis subissue. Some models maybe suitable forreguiation and design,

B Same as C, but some models may beuseful for planning andrelated purposes, and suitabie for determining relative effects.C Modeling lspossible. Credibility andreliability of results is Iowdueto weaknesses in the database.— Modeling of this type is not usually performed.

Overall level of modellng sophistication:O No models available.

10 Routine use of models of all types,

c—

;B

:BBA

AAABA

c——cB

AAccA

AAAcB

AA

:A

c—

zc

A

;B

cAccB

c————

AAAc—

cBccB

AAccA

AAAcB

c————

————

BABcB

ccc——

AAAc—

BABcB

ABccA

AAAcB

AAAcA

ccccc

cc—B

4c————

——A—

9

—3

BA

:B

6AB——A

7

9AAAcA

1ccc——

2———B 3


It is not possible to state categorically that onetype of model is to be preferred over another—inparticular that a Type IV model is to be preferredover a Type 1. The appropriateness of an analyticaltool depends on the particular problem and objec-tives of the analysis. In the most general terms,Type III and IV models have greater potential foraccuracy and credibility than do Type I and II mod-els. But there are many instances in which data andtheoretical formulations are so lacking that the useof a complex computerized model is simply not war-ranted, even if one already exists. For example, thefate of toxics in the environment is of immediateconcern to the public, but the various parametersand coefficients that describe the sources, sinks, andtransformations of these chemicals are so ill-definedthat the sophistication of toxic model formulationsfar outstrips the present data base. Simpler proce-dures are often much more credible.

The evaluation table presents a summary of in-formed opinion regarding the utility of models inanalyzing specific issue areas. Overall, models are

currently judged most successful for the issues ofsalinity, wasteload allocation and thermal pollution.The weakest issue is toxics, due mainly to the lackof data necessary to determine the changes thesesubstances undergo in receiving waters.

Successful modeling for a given issue requiresa good deal more than the application of sufficientmodeling expertise. To model the governing prin-ciples of physical processes, the principles them-selves must be well understood. Scientific under-standing of biochemical phenomena related to waterquality is not sufficiently advanced to permit highlyaccurate modeling; the governing principles of tem-perature, on the other hand, are relatively well doc-umented. Data constraints place a further limita-tion on the utility of models—processes that arethoroughly understood can be accurately modeledonly if data are available to predict conditions forthe location under study. This evaluation accountsfor these factors in assessing model utility, ratherthan simply assessing the state of the modeling artin itself.

GROUND WATER QUANTITY AND QUALITYIntroduction

Ground water systems, unlike surface water sys-tems, are completely concealed from view; conse-quently, conceptual, physical, or mathematicalmodels are the only way to achieve an understand-ing of their potential yields and responses to naturalor man-related stresses. Simple ground water prob-lems may be analyzed using physical hydraulic con-cepts and assumptions, perhaps expressed in sim-ple paper calculations. However, more complex ap-plications require the use of large amounts of data,gathered from multiple test wells at many differenttimes. The only way to integrate this informationinvolves using computers that are capable of solv-ing hundreds or even thousands of complex mathe-matical expressions simultaneously.

Public agencies that issue water use permits orotherwise manage regional ground water resourcesmust rely on models to forecast effects of groundwater use. Applications range from day-to-daymanagement of a community’s ground water use

to long-range Planning for maximizing the utilityu .

of an entire aquifer. Models can be designed, forexample, to calculate how pumping from a new wellmight affect local ground water levels, or to predicthow far contaminants might move in a given periodof time. However, models can also be designed toanswer more complex questions about potentialquantities of recoverable water in regional groundwater systems as more and more wells are drilledand pumped. These evaluations can provide infor-mation for regulatory decisions regarding allowablelimits on total ground water use, optima] pump-ing rates and placement of new wells, or control-ling subsurface waste injection that may contami-nate ground water.

The principal types of situations for which mod-els are used include:

. changes in ground water availability;● changes in ground water levels due to pump-

ing from wells, land drainage, or injectingwater into an aquifer;


●

●

●

changes in ground water flow caused by altera-tions in surface water flow patterns;movement of contaminants through groundwater systems from waste disposal or encroach-ment of saltwater; andsettlement or subsidence of the land surfacedue to withdrawals of ground water.

The greatest limitations on the effective use ofground water models are not computer size or accu-racy, but: 1) the basic understanding of physicaland chemical processes in ground water systems;2) the cost of collecting sufficient field data todescribe the characteristics of the ground water sys-tem; and 3) the availability of well-trained person-nel. In general, ground water quality models aremuch less reliable than ground water flow models.While models are widely used to address groundwater availability questions, many ground waterquality models have not yet been proven reliableenough for routine regulatory application.

Types of Models Used in GroundWater Resource Analysis

Ground water models are usually classified ac-cording to the physical and chemical processes theydescribe. The two major types are: 1) ground waterflow models; and 2) contaminant transport models.Generally, ground water quantity and yield prob-lems are analyzed with flow models, while groundwater quality issues require the use of contaminanttransport models. The two major model types areexamined below, and ground water quantity andquality issues are analyzed in “Ground WaterQuality Issues. ” Lastly, the section evaluates theutility of currently available ground water models.

Ground Water Flow Models

Flow models determine rates and patterns of fluidmovement through soil or rock. Both the type offluid and the nature of the soil or rock are used tofurther characterize the flow model. Types of fluidsmodeled include water only, water and air, or waterand an immiscible fluid (a fluid that does not mixwith water, such as gasoline). The soil or rock typesmay be either porous or fractured material. Flowin porous media is primarily through interconnectedvoids (open spaces) between individual grains. Anexample of this type of material is sandstone. In

fractured media, water cannot move through the rockas in porous flow, but moves through cracks or cav-ities in the rock. In general, better estimates of flowcan be made with models for porous media thanfor fractured media.

Saturated flow models consider the flow of wateronly. These models assume that water completelyfills the open spaces between soil grains or rock.Data used in these models include: 1) inherentcharacteristics of the system, such as the transmis-sivity (ability to transmit fluids) and storage (abilityto store fluids) characteristics of the rock or soil;and 2) changes imposed on the ground water sys-tem, such as water entering or leaving the system.Results from the model consist of calculated fluidpressures or water levels at time intervals for specificlocations in the ground water system. Saturatedflow models are used for almost all types of groundwater quantity applications.

Above the water table, the open spaces betweensoil grains or in rock voids contain air as well aswater. A model that considers a mixture of air andwater simultaneously is called an unsaturated~owmodel. Data requirements for unsaturated flow mod-els include all of those needed for saturated flowmodels plus data describing the reduction in trans-missivity (resistance to water flow) due to the pres-ence of air. Besides fluid pressures, the models alsocalculates variations in the amount of air containedin the pore spaces. Unsaturated flow models areuseful for small-scale problems such as crop irri-gation or water flow adjacent to landfills.

Multifluid models deal with the simultaneous flowof immiscible fluids in the soil or rock—e. g., a gas-oline-water or oil-water model. These models aresimilar to unsaturated flow models, except that gas-oline rather than air is the second component ofthe fluid mixture. Multifluid models can help toassess the consequences of fuel tank leaks or oil spillson land.

Contaminant Transport Models

Contaminant transport models analyze themovement, mixing, and chemical reactions of con-taminated water in the native water and the soilor rock through which it flows. Like flow models,transport models are also classified by fluid and

wmedia types, as well as by the chemical reactionsconsidered.

Three major processes control the movement andchanges in concentrations of pollution in groundwater: 1) movement due to ground water flow(called advection or convection); 2) the mixing ofground waters having different levels of contamina-tion (called hydrodynamic dispersion); and3) chemical reactions. Contaminant transportmodels are normally classified according to whetherthey consider chemical reaction. Two major typesof models are generally recognized: 1 ) conservativetransport models, which do not consider chemicalreactions; and 2) nonconservative transport models,which do.

Nonconservative transport models can simulatea variety of possible chemical reactions. For exam-ple, models may consider the fate of water-bornepollutants that become fixed or adhere to the soilor rock surface, thereby coming out of solution andnot moving with the water. However, while theseand more complex reactions can be addressed intheory, in practice, chemical reactions are normallyeither ignored or are approximated by simple equa-tions. Simple equations are used because the precisemechanisms for the chemical reaction are general-ly unknown or are too complicated to be used infield applications.

Data required for both conservative and noncon-servative transport models include the hydrologic

146 ● Use of Models for Water Resources Management, Planning, and Policy. . — —

data discussed previously for flow models, as wellas data describing mixing and chemical reactions.Models generally calculate projected concentrationsof the various pollutants as they vary over time andspace.

Because ground water flow is a major factor af-fecting the movement of contamination, pollutanttransport models are necessarily extensions ofground water flow models. As a result, a contami-nant transport model is, at best, as reliable as theground water flow model to which it is coupled.For small-scale contamination problems in materialthat is highly variable or is fractured, estimates ofground water flow may be inaccurate, thereby re-ducing the reliability of transport estimates.

In addition to ground water flow, the movementof pollutants is affected by mixing and by chemicalprocesses, both of which are poorly understood.Since quality problems are more complex thanquantity problems, models dealing with groundwater quality are generally less reliable than thosefor ground water quantity. Quality models are alsoconsidered less credible than quantity models be-cause of their recent origin and the relative unavail-ability of validated models.

Ground Water Quantity Issues

Available Supplies and Optimal Yields

Models are well suited for determining the hydro-logic limitations on ground water availability, oron the yield of an aquifer. Hydrologists have devel-oped several definitions of what constitutes an aqui-fer’s yield. One definition, “sustained yield, ” rep-resents the maximum amount of water that can beremoved from the system if inputs and outputs areto be balanced, with no net loss from the aquifer.The concept is based on the commonsense obser-vation that water cannot be continually withdrawnfrom wells if the rate of withdrawal exceeds thenatural rate of replenishment to the ground watersystem. A second definition, ‘ ‘optimal yield, in-corporates political and social considerations, andrefers to an optimal plan for using a ground watersystem, whether on a sustained basis or not. Thisapproach attempts to maximize economic objectivesand to minimize environmental impacts throughlegal and social constraints on the use of the groundwater supply.

Computer models can be very useful tools for es-timating an aquifer’s response to alternative devel-opment plans. Assuming that the geometry andwater-bearing characteristics of the ground watersystem have been adequately described, the model-er uses equations to show, for example, how waternaturally enters the system from infiltration of rain-fall or streamflow, how water naturally escapes fromthe system through discharge into surface waterbodies or through consumption by vegetation, andhow the extraction of water from wells affects theoverall water balance.

The response of a ground water system dependsnot only on hydrological conditions, but also on themanner in which the ground water is withdrawnfor use. For example, locating wells too close to eachother may cause large water-level declines near thewell field, resulting in reduced yields, dry wells, oreven subsidence of the land surface. Ground waterflow models can be used to address problems suchas the optimal design of a well field and the extentof available supplies, and to predict water-level de-clines due to alternative development schemes.

Although the most frequent use of ground waterflow models is for water-supply management, thesemodels can be helpful throughout the planningstages preceding management decisions. Modelsalso provide a framework and guide for collectingand organizing data. By matching computed modelresults with observed system behavior, one can gaina better understanding of hydrologic and geologicconditions. Even with limited data, the hydrologistmay use a model to test alternative hypotheses ofhow the system behaves.

For managing, regulating, and planning the useof ground water, models that determine availablesupplies and optimal yields are highly reliable.However, since ground water data are derived pri-marily from wells, aquifers that are relatively unde-veloped often have an inadequate data base for esti-mating potentially available yields. As the systemis developed, more data become available, and ear-lier modeling efforts can be modified to reflect thisadditional information. Thus, data collection andmodeling activities must be coordinated with aqui-fer development if reliable information about theground water system is to be available when it ismost needed—when water withdrawals are largeenough to significantly affect the aquifer.

Ch. 6—Modeling and Water Resource issues ● 147

Conjunctive Use of Ground and Surface Waters

Aquifers are commonly hydrologically connectedto surface lakes and streams. Ground water fre-quently provides the base flow to streams—thestreamflow that occurs even during dry weather.During periods of low rainfall, the base flow pro-vided by ground water is a major determinant ofboth the quantity and quality of surface water. Adecline in ground water levels may decrease thebase flow and degrade surface water quality. Inother situations, surface water may recharge theground water system. In this case, a change in thequantity or quality of the surface water would af-fect the ground water.

Conjunctive use models analyze the interactionbetween ground and surface water systems. Thesemodels may provide information about both quan-tity and quality aspects of surface water and groundwater interrelationships, and can be used to aid inthe combined management of both water sources.Ground water flow models have been employed formany different conjunctive-use situations. A typicalproblem of this kind involves determining the ef-fects on surface water flows of irrigating withpumped ground water distributed through irriga-tion systems. The ground water flow models usedfor these applications are essentially the same asthose used to determine optimal yields. For con-junctive use, however, the components of the modeldescribing the interaction between ground and sur-face waters become critical and are consequentlymore complex.

During the past decade, ground water flow mod-els have frequently been used to solve conjunctiveuse problems. Model reliability is nearly as highas for ground water supply and optimal yield ap-plications; confidence is somewhat reduced, how-ever, because quantitative estimates of the interac-tions between ground and surface waters are diffi-cult to obtain. Furthermore, the scale of the sur-face water problem (i.e., area of influence and speedof water movement) may differ from that of the as-sociated ground water system. This may result inan accurate description of the ground water re-sponse but a less satisfactory description of localsurface water responses.

Subsidence of the Land Surface

Under certain geologic conditions, particularlywhere thick beds of clay underlie the land surface,heavy withdrawals of ground water may lowerground water levels to such an extent that the clayspartially dry out. In some situations these claysshrink or compact, resulting in settling or subsi-dence of the land surface, which may cause rup-tures in pipelines, cracking of building foundations,or even surface water floods. The Houston ShipChannel in Houston, Tex., is a notable example—several adjacent residential communities have es-sentially been abandoned because flooding by tidalwaters has resulted from land surface settlement.

To model these conditions, data are needed notonly for the ground water system itself but also forsoil mechanics and physical properties of clay soilsunder dry conditions. In addition, information isneeded about the surface water systems in areaswhere subsidence may alter drainage areas and flowpatterns.

Ground Water Quality Issues

A basic understanding of ground water flow isnecessary for understanding ground water qualityproblems. Since pollutants entering a ground watersystem are carried along with the water flow, manyof the factors that determine quantity relationshipsalso apply to quality models. Problems of groundwater quality are likely to dominate water resourceissues in the 1980’s. They fall into four broad cat-egories: 1) accidental and negligent contaminationfrom urban and industrial areas; 2) agriculturalpollutants to ground water; 3) movement of pol-lutants into and through ground water from wastedisposal; and 4) seawater intrusion.

The disposal of wastes, in particular, involvesmajor political issues for which the analytical capa-bilities of models will be useful. Wastes can be dis-posed of in the atmosphere, in streams and othersurface water bodies, or into or on the solid earth.Each of these options has associated tradeoffs. In-land and onland disposal of either solids or liquidsmay contaminate ground water and cause wastesto be transported long distances from the original


disposal site. Consequently, ground water hydrolo-gists are being asked to predict the movement ofcontaminants to aid in designing waste-disposalsystems to minimize contamination. The problemis perhaps best exemplified by the present searchfor a geologic disposal site for high-level radioac-tive wastes.

Accidental and Negligent ContaminationFrom Urban and Industrial Areas

Unintentional ground water pollution is reportedwith increasing frequency. Regulatory agencieshave particular difficulty in planning for emergencyincidents of ground water pollution, due to the widevariety of possible contaminants and hydrogeologi-

11 - M /

cal conditions. Contaminant transport models, inconjunction with careful hydrologic studies, canprovide important information on alternative cor-rective measures.

This section deals with unintentional, nonagricul-tural contaminants to ground water. Three fre-quently occurring pollutant types will be discussed:1) petroleum products; 2) industrial chemicals; and3) road salts. For each of these, contaminant trans-port models can be used with varying degrees ofsuccess and confidence. Model capabilities are lim-ited primarily by insufficient data on and under-standing of the movement of contaminants throughsoil and rock. It is often necessary to drill numeroussampling wells to determine the extent of the con-tamination. Other information that is needed in-cludes the amounts of contaminants released andthe chemical reactions occurring in the soil.

Petroleum spills and leaks are serious sources ofground water contamination. Hundreds of thou-sands of gasoline storage tanks, thousands of milesof underground pipelines, and numerous tanktrucks and railroad cars carry oil or gasolinethroughout the country. Contamination from thesesources is quite difficult to analyze with models.Models of the movement of oil or gasoline havebeen routinely employed for petroleum reservoirengineering, but have had limited application toground water problems. Insufficient experiencewith these models limits their use for analyzing con-taminant transport.

P

Photo credits: @ Ted Spiegei, 1982

Extensive ground water withdrawal can cause land to subside on small or large scales. At left, signs on telephonepoles in the San Joaquin Valley, Cal if., show the sinking of the Earth’s crust as a result of ground water use for irrigationsince 1925. Florida sinkhole at right demonstrates a more dramatic local effect. At any scale, land subsidence in inhabitedareas has enormous destructive potential; developing models to estimate the conditions under which subsidence will

occur requires extensive knowledge of geology, ground water hydrology, and soil sciences


Although oil and gasoline do not generally mixwith water, small concentrations of petroleum prod-ucts may dissolve. These low concentrations mayexceed acceptable water pollution standards. Themovement of dissolved oil or gasoline can be ana-lyzed by contaminant transport models once thenature of the dissolution process is known. Thesemodels can be used to gage the effectiveness of var-ious cleanup procedures.

Toxic industrial chemicals can accidently contami-nate ground water supplies in a number of ways—leaky storage tanks, tanker spills, or leaky holdingponds. The range of possible contaminants makesit difficult to use models to predict resulting pollut-ant concentrations. In general, for chemicals thatdissolve in water but do not react with soil or rock,credible models can be developed if sufficient hydro-logic data exist. However, for chemicals that areeither immiscible with water or reactive with soilor rock, model reliability will be low, regardless ofthe amount of hydrologic data available. Still, forsuch reactive constituents, conservative or ‘ ‘worst-case’ predictions can be useful for assessing themaximum pollution potential, and can be generatedby assuming that no reactions occur. In these cases,model results can aid in evaluating alternativeremedial measures.

Large quantities of salts are applied to roads dur-ing icy conditions, primarily in Northern States.Road salt is highly soluble in water; thus, shallowground water supplies near major roads may be-come contaminated. In recent years, recognitionof this problem has led to decreased usage of roadsalt. While contaminant transport models can assessthe potential for ground water pollution from roadsalt use, the problem is not generally consideredserious enough to warrant the collection of the ex-pensive field data needed to produce credible re-sults.

Agricultural Pollutants to Ground Water

Agriculture, because it is so widespread an activ-ity, is an important influence on the quality ofground water. Agricultural activities can affectground water quality through: 1) salt buildup, and2) contamination by herbicides and pesticides.

Salt buildup is caused in two ways. In semiaridregions, fields close to streams are commonly irri -

gated with both surface water and pumped groundwater. As the water flows through the ground andreturns to the stream, it accumulates salts from thesoil that are further concentrated by evaporationfrom soil and plants. The water returning to thestream often has high salt concentrations and issometimes unusable for irrigation by farmers down-stream.

Salt buildup can also occur as a result of fertiliz-ers, and, to a lesser extent, from storage or disposalof livestock wastes. Fertilizer is a serious source ofpollution. Nitrates— a major component of fertilizerand a type of salt—are the most common cause ofground water contamination beneath agriculturallands.

The use of pesticides and herbicides has expandedsignificantly in recent years, When pesticides andherbicides are applied to the land, they migratedownward toward ground water supplies throughthe unsaturated zone. They generally move slow-ly, and undergo chemical changes in the unsatu-rated zone that alter their properties. Pesticides andherbicides that are “broken down’ in this man-ner are often not harmful when they reach theground water. However, the greater the use of pes-ticides and herbicides, the higher the likelihood ofproducing concentrations exceeding the biodegra-dation capabilities of the unsaturated zone. Seriousground water pollution can result in such cases,

Models of ground water flow and transportthrough saturated soil and rock are generallyreliable when applied to these problems. Waterquality variations in an irrigated stream-aquifersystem can be reliably predicted with mathematicalmodels, if sufficient data are available.

Flow and transport in unsaturated zones are lesswell understood; consequently, unsaturated flowmodels are less reliable than saturated ground watermodels. As yet, no model has been developed thatincorporates all the physical, chemical, and biologi-cal processes occurring in the unsaturated zone.However, many problems involving pesticide-her-bicide ground water contamination can be analyzedwithout a comprehensive model, Simplified modelsare useful for assessing the effectiveness of the un-saturated zone as a barrier to potential pollutants.Results based on conservative or worst-case as-

150 ● Use of Models for Water Resources Management, Planning, and Policy—

sumptions may be helpful for determining the ef-fects of agricultural practices on ground water.

Movement of Pollutants Into and ThroughGround Water From Waste Disposal

Several methods are commonly used for onlandwaste disposal:

● landfills;. surface spreading;. surface impoundments; and● injection wells.

Approximately 5 pounds of solid wastes per per-son are produced daily in the United States. Solidwaste is normally reduced in volume by compac-tion and placed in landfills, which currently numberover 150,000 in the United States. When rain entersa landfill and infdtrates through the refuse, byprod-ucts of waste decomposition dissolve in the water,producing a liquid known as leachate. Leachate canbe a serious problem in nonarid regions, where ris-ing water tables infiltrate refuse, causing contami-nants to migrate into the ground water system.Such leaching of pollutants may continue for dec-ades or even hundreds of years. Models can be usedto predict the effects of alternative engineeringdesigns on the landfill hydrology, and to predictthe transport of leachate into ground waters. Thesemodels are still in initial stages of development.

Much domestic waste in the United States isprocessed in secondary sewage treatment plants.A common practice for disposing of these waste by-products is to spray liquid sewage on and spreadsludge over the land surface. Surface spreading ofsewage and sewage sludge may degrade groundwater quality, both through salt buildup and fromheavy metals that are not removed during second-ary treatment. Since this practice is similar to fer-tilization, modeling capabilities and difficulties aresimilar to those described for agricultural practices.

Surface impoundments are pits, ponds, and lagoonsin which liquid wastes are stored, treated, and dis-posed of. These wastes contain a wide variety oforganic and inorganic substances. Over 170,000impoundments are located in the United States—many of them contain potentially hazardous wastes.Few of these impoundments have a bottom liner,

and few have means for monitoring ground waterquality.

Contaminants that seep from impoundmentsmay be modified in the soil by various chemicalreactions, thus reducing their harmfulness; othersmay move into shallow ground water and cause pol-lution. Studies generally show that ground watercontamination creates a contaminant plume thatmay be well contained locally, but might extendup to a mile or more from the impoundment, de-pending on ground water conditions.

Actions that can be taken to alleviate contamina-tion

●

●

●

of ground water include:

lining the impoundment with plastic, impervi-ous clay, asphalt, or concrete;constructing collection systems such as wellsfor recycling; andreducing the movement of contaminatedground water by means of hydraulic or phys-ical barriers.

The effectiveness of these actions can be evaluatedwith mathematical models. The approach to analyz-ing contamination from impoundments is similarto that used for landfills.

Wastewater injection wells offer an alternative todisposal of waste at or near the land surface. Asof mid- 1973, at least 278 industrial wastewater in-jection wells had been installed in 24 States, and170 of these wells were operating. Most were be-tween 1,000 and 6,000 ft deep and had average in-jection rates of less than 400 gallons per minute.As with other pollution problems, chemical and bio-logical reactions occurring within injection wells arethe most difficult to model accurately. Nonetheless,models may still be used to estimate the impact ofthe injection system on the natural hydrology; this,in turn, may be used to design well fields and injec-tion schemes.

Seawater Intrusion

Cities in coastal areas often withdraw large quan-tities of ground water for their freshwater supplies.This decreases the seaward flow of freshwater,which may cause saltwater to move into groundwater reservoirs.

Ch, 6—Modeling and Water Resource Issues 151— —

The movement of seawater into drinking watersupplies in coastal areas is a serious and widespreadproblem. Models can aid in designing well fieldsand pumping schemes to minimize seawater intru-sion. However, for cases in which the hydrologyis complex, such as a layered ground water systemin which flow characteristics among the layers varygreatly, modeling results are less reliable.

Evaluation of Currently AvailableGround Water Models

In table 9, models that can be applied to eachof the problems previously described are evaluatedaccording to model types employed and the models’areal scale of analysis. The evaluations are for the

general level of model development in each cat-egory, rather than for any specific model. A com-prehensive list of models available for ground wateranalysis is provided by Bachmat, et al. 1

Two major criteria are used to evaluate eachmodel category: 1) model reliability; and 2) credi-bility of model results. Models are considered reli-able if they can accurately describe the importantchemical and physical processes. Credible resultsrequire both a reliable model and sufficient datato run that model. For some applications, modelsmay be reliable, but the cost and difficulty of col-

IY. B. Bachmat, et al. , ‘ ‘Utilization of Numerical Ground \\’atcrModels for Water Resource Management, ” U.S. Environmental Pro-tection Agency, report No. EPA-600 /8-78-Ol 2, 1978.

Table 9.—Ground Water Model Evaluation

spatial ConsiderationsModel types

Site Local Regional

Transport Transport TransportTransport WIO Transport WI Wlo

Pollutant movement, if anyWI Wlo

Flow only reactions reactions Flow only reactions reactions Flow only reactions

un

Fiow conditionssat sat sat multi sat sat : ; t sat sat M sat sat sat sat sat sat sat sat sat sat

P F p fluid P F F’ P F P P F P F p F p F p F

IssuesQuantity—available supplies. . . . . B c A B B B

Q u a n t i t y — c o n j u n c t i v e u s e . B R A B B B

Quality —accdental petroleumproducts. . . . . . . . . . R B c R c R

Quality—accidental road salt, . . . . B c cQuality—accidental industrial

chemical . . . . . . . . . . . . . . . . . . . . B c c c R – B c c –Ouality—agricultural pesticides

and herbicides. . . . . . . . . . . . . . . B c c c R – B c c –Quality–agriculture salt buildup. . B c c B cQuality—waste disposal landfills. B c c c R – B c c –Quality—waste disposal injection. B c c c R – B c c –

Quality—seawater intrusion. . . . . . B B c c 0 c c cKey

Rows — issue and subissue areas discussed in textColumns — model types and scale of applications; e g, the sixth column applies to a site-scale problem in which Pollutant movement IS described by a transport

model without chemical reactions under saturated flow condltlon in fractured mediaApplication scale

Site—models delaing with areas less than a few square milesLocal—models dealing with areas greater than a few square miles but less than a few thousand square milesRegional—models dealing with areas greater than a few thousand square m!les

Abbreviationsw/—withw/o—without.sat—saturated ground waterfiow conditionsunsat —unsaturated flow conditionsP—porous mediaF—fractured or solution cavity media

Entr!esA a usable predictive tool having a high degree of rellablllty and credlb!l!ty given sufficient dataB a reliable conceptual tool capable of short.term (a few years) prediction with a moderate level of crediblltty gwen suff!ctent dataC a useful conceptual tool for helping the hydrologist synthewze complicated hydrologic and quality dataR a model that IS still In the research stage— no model existsBlank—model type not applicable to issue area


lecting data may prevent calculated results frombeing very credible. The ratings assigned for eachmodel category are a composite of these two con-siderations.

The key at the bottom of table 9 describes theterms employed, and briefly summarizes the modelrating scheme, the breakdown of model types, andthe measurements used to define different levels ofscale. Explanations of the rating scheme, and ofscale and time considerations in model evaluation,are provided below:

Model Rating

A rating of‘‘A ‘‘ indicates that models are reli-able and can be applied with credibility to a par-ticular problem. It also implies that data necessaryto use the model can be obtained at reasonablecosts. Models with ‘ ‘A’ ratings can be used effec-tively for making decisions on applicable problems.

Models rated “B” can be used for short-termpredictions with confidence. The lower level of cred-ibility implies that either some part of the processesdescribed is not fully understood, or that data nec-essary to use the model may be too expensive ortoo difficult to obtain. These models can be appliedto field problems if their limitations and capabilitiesare recognized. Further, if field data were collectedon a continuing basis and incorporated into themodel, model credibility would improve. Modelswith “B” ratings can also be used to investigategeneral problems (but not specific field applica-tions). Conceptual investigations can be used indesigning regulations and policy, e.g., for deter-mining landfill siting criteria.

Models rated ‘‘C” have not been sufficiently val-idated for analyzing specific problems. Both expen-sive data collection and inadequate understandingof important processes are likely for these models.Models with “C’ ratings have utility as concep-tual tools for investigating general problems.

Models having a rating of “R” are still in devel-opmental research stages. In the future, these mod-els should earn a higher rating as they are validatedthrough field use.

Models described by “-” are not presentlyavailable.

Area/ Scale. The credibility of ground watermodels is highly dependent on the geographic scaleof the study area. Most models are designed to op-erate at the local scale (area greater than a fewsquare miles but less than a few thousand squaremiles). Therefore, more confidence may be placedin models used for this scale.

Time Scales. Ground water models project futureconditions for widely varying intervals of time.Generally, the longer the range of the prediction,the less reliable it is. Ground water models normallyinvolve planning horizons of 20 to 30 years, andeach model varies in its ability to forecast futureconditions. For many hazardous waste problems,the time frames needed are much longer, sometimesranging to hundreds of years. Results from suchprojections are much less credible than results frommodels used for problems with shorter time frames.While time frames are not specifically consideredin the evaluations, the effects of different time pro-jections on the credibility of model results must beconsidered in evaluating specific models.

ECONOMIC AND SOCIAL MODELS

Introduction

Many different types of models and analytic tech-niques are used to determine the economic andsocial consequences of water resource activities, toforecast consumer and industrial water needs, andto analyze water resources for comprehensive riverbasin planning and management. Social and eco-nomic models address patterns of human behavior

using theories drawn from economics, sociology,social psychology, geography, and political science.

Economic models are used to estimate the overalleffects of water resource activities and regulationsat both the regional and national levels, as well asto forecast economic consequences to individualsand firms. For example, an economic model canforecast changes in an industry’s water use as the


cost of obtaining water changes, and determine theeffect of such changes on industrial output.

Social models can project population trends, esti-mate water demands, and analyze the social struc-ture of a given area. They can be used to identifythe groups likely to be affected by resource deci-sions, and their perceptions of these effects. Socialmodels can be coupled with economic models toevaluate the societal implications of water resourceregulations or projects.

The use of social and economic models is relative-ly new in the water resources field, as in other fields.Social and economic model use in water resourceanalysis has been prompted by two major regula-tions: 1) the Principles and Standards (P&S) of theWater Resources Council; and 2) the National En-vironmental Policy Act of 1969. The P&S are agroup of publications that presently require con-sideration of the likely effects on environmentalquality and national economic development of proj-ects proposed to receive full or partial Federal fund-ing. The P&S also require studies of the effects ofproposed projects on regional development and onthe social well-being of the affected area. The Na-tional Environmental Policy Act requires estimatesof the social and economic effects of proposed proj-ects. To make such estimates, social models can beused to identify the population that would be af-fected by the resource decision, and the extent ofthe likely effects. Economic models are also em-ployed to determine the economic impacts of a proj-ect on individuals, firms and the region overall.

Several factors account for the increasing use ofsocial and economic models. Models may providethe only available means of organizing complex in-formation for examining the effects of an action orpolicy. Information derived from the conditions andscenarios assumed in a model can provide insightsabout the effects that may occur, and serve as abasis for common discussion of assumptions andprobable outcomes. Finally, social and economicmodels can be used to compare the merits of pro-posals in terms of a particular objective, and helpdecisionmakers determine the costs and benefits ofa proposed decision.

Both social and economic models are limited by

the necessity of dealing with human behavior,which is not always predictable. Behavior is difficult

to incorporate in a model except in an abstractway—identifying behavioral tendencies with in aprobability of outcomes. Another problem, moreprevalent among social models, is that they aredata-limited. Available data often prohibit quantify-ing and analyzing all factors involved in determin-ing the ‘ ‘public interest ‘‘ in any given situation.Thus, ‘ ‘decision’ models of social and economicfactors can only be used as guides—they cannot besubstituted for the human decisionmaking process.

Because of the difficulty in evaluating social sci-ence models, and their less advanced state of devel-opment, these models were not formally evaluated.Few social science models are widely adaptable;moreover, such models are difficult to validate bycomparing predictions to results, as is routinely

done for models of physical processes. Assessing therelative utility of these models requires comparisonsof previous model applications under a variety ofconditions by different analysts, and necessarily in-volves a considerable component of subjective anal-ysis.

Basic Analytical Characteristics

Social science models are classified by the kindsof information they generate. Three major distinc-tions are used to identify significant characteristics:1) descriptive v. normative; ‘2) macroscale v. micro-scale; and 3) efficiency v. distribution of costs andbenefits.

1. Perhaps the most important dimension involvesthe distinction between descriptive and norma-tive models. A descriptive model is an empiricaland historical representation of ‘what is. De-scriptive models determine factual relationshipsas they exist or may be expected to occur. Theyare intended to include a minimum of subjec-tive assumptions and biases.

A normative model may be equally reliable andcredible, but it focuses deliberately on ‘‘whatshould be. Normative models include substan-tial judgments and assumptions about goals andobjectives. For example, a descriptive model ofthe Nation’s economic output would simply re-port actual or expected levels of gross nationalproduct (GNP), while a normative model mightinclude the assumption of a 5-percent annual in-crease in GNP as an economic goal. Most of the

2.

Photo credit: U.S. Department of Agr/cu/ture

Water resources development can have tremendous effects on an area’s ability to attract residents, industry, and relatedactivity. Models are available to estimate how construction expenditures may directly affect local or regional economies,as well as how water facilities could affect subsequent development. In addition, models can describe how water-related development could affect demands for a wide range of public services, for example, schools, hospital facilities,

roads, and other infrastructures

current social and economic models used inwater resource analysis are normative, i.e., sub-stantial a priori value judgments have been madeabout the goals, objectives, measures, and meth-ods used in the model.

Scale is the second feature by which social sci-ence models can be categorized. Two distincttypes are recognized—macroscale models andmicroscale models. Macroscale models address ag-gregate changes or activities. Macrolevel modelsinclude those that measure and forecast trendssuch as levels of national economic activity (e. g.,GNP), money supply, international trade, mi-gration patterns, etc. They are useful for pro-viding national and regional analyses of waterresource projects and programs.

3.

Microscale models focus on individual and/orenterprise-level behavior. They are often usedin water resources for feasibility studies, environ-mental impact statements and other project-plan-ning activities. Microscale models are used toaddress, for example, pricing, benefit/cost, socialimpact, and risk/benefit questions.

A third feature of social science models addressesthe dual questions of efficiency and distribution ofcosts and benefits. Water resource policies or activ-ities affect both economic efficiency and the dis-tribution of costs and benefits. Efficiency is de-scribable by economic models, while addressingthe distribution of benefits requires a broadersocial analysis, Models of economic efficiencyfocus on means of increasing the gross supply


of goods and services. Distributive models tracechanges in assets and/or income distributionamong either resource owners (e. g., labor, cap-ital, management) or major sectoral groups(e. g., farmers , industrial workers, the unem-ployed).

Types of Models Usedfor Economic Analysis

Four types of economic models are widely usedfor dealing with water resource issues: 1) input-output; 2) optimization; 3) econometric; and4)

1.

2.

3.

simulation.

Input-output models are based on a detailed ac-counting of sales and purchases among each ofthe industries or sectors being studied. Informa-tion on purchases and sales is used to determineeither the requirements for particular inputs(e.g., water) or the production of outputs (e. g.,manufactured products).

Optimization models are used to determine the allo-cation of resources that best meets a previouslyspecified objective (e. g., least cost), subject tosome specified constraints. The technique is par-ticularly well suited, therefore, to solving prob-lems where both the objectives and the con-straints are clearly defined. When more than oneobjective is considered, these models can describethe tradeoffs between the best solutions for eachrespective objective.

Econometric models are a less homogeneous groupthan the two previously discussed classes of mod-els. The term is generally used to describe fore-casting models, the structures of which have beencarefully estimated from historical data. Thelarge, national forecasting models (e. g., Chase,Wharton, Data Resource, Inc. (DRI), etc. ) areof this type, as are many models tailored toregional and State needs. Econometric modelsare typically based on the following macroeco-nomic principles: 1 ) production determines in-come; 2) income determines demand; and3) production, in turn, adjusts to demand. Theinteractions among production, income, and de-mand determine economic multiplier effects,which play an important role in economic im-pact analysis.

4. The fourth class of models is referred to here assimulation models. Economic simulation modelsare often input-output or econometric modelsthat are adapted to examine the implications ofdifferent sets of assumptions. Simulation modelsdescribe the highly involved pattern of cause-and-effect relationships that operates within mostsocial or economic systems. Once relationshipsare identified and the key factors have beenquantified, the model is used to simulate theperformance of a system over a period of time,under different sets of assumptions about thesystem’s internal relationships and the values ofexternal variables. Such models can calculate theincremental effects of price changes or im-provements in production methods, for example.

Other Social and EconomicAnalytical Techniques

In addition to traditional economic analysis andthe four model types identified above, an increas-ingly large set of social and economic analyticalmethods is being used in natural resource planningand policy evaluation. The methods are diverse,so they will be discussed here according to the kindsof relationships they are designed to explore.

A major consideration in planning and policyanalysis is the size and demographic structure of thepopulation. Demographic models, therefore, relateinformation about the present size and structureof the population to projected changes due to birthsand deaths or to population shifts. Most of thesemodels deal with specific age, sex, and racial groupsor cohorts, and are consequently referred to as co-hort survival models,

Another set of analytical techniques has been de-veloped to deal with the demands for, and supply ofinfrastructure—factors such as housing and publicfacilities and services. These techniques are usedby planners to determine the fiscal impacts on gov-ernments —including both expenditures and collec-tion of revenues—of providing various levels of in-frastructure services, Standard models are availableto carry out these infrastructure and fiscal impactcalculations, although variations among jurisdic-tional units require adjustment for the particularunit of government being considered.


Once economic, demographic, and public sec-tor behavior has been accounted for, a major re-maining concern is the social structure of an area. Fewcomputer models have been developed to analyzethis problem, but progress is being made in defin-ing social structure, and in understanding how itis affected by natural resource decisions.

The final major area of activity for socioeconomicanalysis is the integration of the various economicand social concerns discussed above. The modelsdiscussed above provide measures of change in theeconomic, demographic, fiscal, and social environ-ment. However, the significance of these changesultimately depends on the perceptions and valuesof the people who will be affected by them. Cur-rent research is underway in identifying groups thatmay be affected by resource decisions, and deter-mining their evaluation of the social and economicchanges that may affect them. Methods for quanti-fying these analyses, however, are in relatively earlystages of development.

Economic and Social Issuesin Water Resource Analysis

Effects of Water Pricing on Use

Severe water shortages in many locations haveprompted investigation into strategies for reducingthe demand for water. Water use restrictions havecommonly been used for managing water use, butother methods that rely on economic incentives(water pricing and conservation subsidies) havepotential for reducing the consumption of waterthrough nonregulatory approaches.

Water demand models, which predict the re-sponse of water demand to changes in water costs,have been developed for residential, industrial, andagricultural uses. The cost of using water, as con-sidered by these models, includes both prices paidfor water delivery and other acquisition and usecosts, such as costs of disposing of used water.

Residential/ water demand models are based on ac-tual household water use behavior. Consumer de-mand theory suggests that the quantities demandedare related to water price, consumer characteristics(income, family size), and factors such as theseason, and extent of outdoor use. Data are col-lected on household water use and on factors which

affect that use. Using statistical analyses, the ef-fect of price can be isolated from the effects of allother variables influencing residential water use.

The models analyze actual consumer responsesto water prices. However, because responses toprices vary among regions and among incomegroups over time, model estimates will be region-,time-, and income group-specific. These models areuseful planning tools, provided that adequate dataare available and that analysts recognize the theo-retical and statistical assumptions underlying themodel.

Industrial and agricultural! water demand can also beanalyzed with mathematical models. Because largewater users are often self-supplied, market pricesfor water in the conventional sense do not apply.However, analyses for these demand sectors arebased on the costs borne for using water. Thesemodels consider the objectives and constraints thatgovern agricultural and industrial decisions aboutlevels of production and amounts of raw materialsto be used, including water. The influence of waterprice on use is inferred by examining the models’predictions of water use changes as water costschange.

These models are not based on observed re-sponses to price change. Rather, they are simula-tions of responses that could be expected from ‘ ‘ra-tional’ water users with objectives and constraintssimilar to those described in the model. To the ex-tent that water users deviate from the objectives andconstraints assumed in the model, model predic-tions will be inaccurate. A number of these modelshave been developed; however, their use requireshighly skilled analysts and good data bases.

Both types of water demand models are usefultools for water resource decisionmaking. If properlydeveloped, they can organize complex informationabout the factors that determine water use, and as-sess the importance of price relative to other fac-tors in determining use. Information provided bysuch models is helpful for developing demand man-agement strategies, including changes in prices ofpublicly supplied water (e. g., at municipal systemsor Federal irrigation projects) or marketing of waterrights, where market prices are determined by will-ing buyers and sellers. These models are useful forcomparing alternatives, but are less reliable for pro-

Ch. 6—Modeling and Water Resource Issues 157

vialing quantitative estimates of actual volume de-mands.

Cost to Industry of Pollution Control

Pollution control costs, like the availability andcost of water, are one of many factors affecting theprofitability and location of industrial activity.Models are used to determine the effects of regula-tions on specific industries, as well as the impactof pollution control policies on the economy as awhole. Costs of pollution control can be assessedat both macroeconomic and macroeconomic levels.Macroeconomic costs are those associated with aparticular firm or industrial group, and include di-rect expenditures for pollution control equipment,costs of changing production processes, and fore-gone production. Macroeconomic costs are gagedby calculating the effects of industry expendituresto meet environmental regulations on employmentlevels, the Consumer Price Index (CPI) and GNP.

Macroeconomic models are the most complex ofall economic models. Their development and userequires highly skilled personnel. For example, themodels of DRI, and Chase Econometrics, Inc.,which are among the best known of this type, havebeen used to evaluate changes in macroeconomicvariables in response to industry expenditures forcompliance with environmental regulations. How-ever, some analysts consider it inappropriate to usethese models to measure ‘ ‘costs of pollution con-tro l . While the models can predict movements inthe CPI or GNP, they do not estimate the economicvalue of a cleaner environment (e. g., reduced healthcare costs, workdays lost due to illness, etc. ) as anoffset to the cost of pollution control equipment.The reliability of these models is difficult to test;their use depends largely on the plausibility of as-sumptions made about inputs and the lack of credi-ble analytical alternatives.

A4zc~oecomrnic moa!ds of costs to industry for pollu-tion control are most often optimization models,similar to those described in the above section onwater demand. Models of this type can be devel-oped for ‘‘typical firms ‘‘ in specific industries. Abaseline condition is first determined by applyingthe model without environmental regulations. Envi-ronmental regulations are then introduced as a con-straint on the firm’s resources and outputs. Prop-

er interpretation of the results can provide estimatesof the costs that firms incur as a result of regula-tions. Limitations and potentials of this type ofmodel are similar to those of water demand models.Models of this type are used for determining theleast-cost approach to environmental regulations.These models have been used to a limited extentby EPA in the water quality regulatory process. Itis likely that greater use of these models will bemade in the future, for reviewing existing or pro-mulgating new environmental regulations.

Benefit/Cost Analysis

Benefit/cost analysis measures the value of a pol-icy, program, project, or regulation in terms of eco-nomic efficiency. Procedures for calculating thebenefits and costs of Federal water resource activ-ities are outlined in the P&S of the Water ResourcesCouncil.

A relatively small portion of Federal activities inwater resource protection and development is nowcovered by the P&S. Affected agencies (principal-ly the Corps of Engineers, Soil Conservation Serv-ice, Bureau of Reclamation, and Tennessee ValleyAuthority) prepare estimates of some costs and ben-efits of their proposed investment projects. How-ever, some of the most common Federal activities—e. g., waterway and discharge permits, and sew-age treatment construction grants—are not re-quired to prepare benefit/cost analyses.

Although economists have developed rigoroustheoretical standards for determining the propermeasure of both costs and benefits, even the mostcompetent analysts face difficulties in conductingsound benefit/cost analyses. Many costs and bene-fits may be known, and yet be difficult to defineor quantify accurately— in water resource activities,more incommensurable benefits tend to be encoun-tered than incommensurable costs. Constructioncosts for building a dam or a sewage treatmentplant, for example, are easier to estimate than thevalue of decreased likelihoods of flooding, or thevalue of cleaner water to downstream users.

When no professional consensus exists as to themonetary value of a benefit, or the probable costof an activity, standards of accuracy for benefit/costanalysis are difiicult to establish. Estimating the val-

—


ue of less tangible benefits necessarily involves anelement of subjectivity; consequently, such esti-mates are affected by the assumptions of the analyst.The choice of a particular time frame or discountrate, for example, while not imparting intentionalbias, may heavily influence results.

As a general rule, benefits and costs of publicprojects are easiest to evaluate when the resources,goods, or services produced are traded in themarket economy (e. g., power production). Benefitsand costs are less easy to measure if the resource,good, or service either contributes directly to a goodwhich is traded (e. g., irrigation water as a factorin agricultural production), or if the private marketoffers a comparable substitute for the public proj-ect’s output (e. g., railroad transportation as asubstitute for river transportation). Benefits andcosts are very difficult to estimate for resources,goods, or services for which few market transac-tions exist (e. g., recreation, wildlife habitat). Inthese cases, the economic value of the public proj-ect cannot be inferred from observed market prices.

Institutional limitations on the alternatives thatcan be considered for achieving an objective consti-tute another constraint to effective use of ben-efit/cost analysis for Federal water activities.Benefit/cost analysis is most useful when it is usedas a screening device for comparing alternatives.If an agency, for example, is restricted to fundingflood control structures and cannot propose pur-chasing flood plain development rights as a non-structural alternative, the full power of theanalytical technique cannot be effectively used.

Benefit/cost analysis is often used to support nor-mative arguments that no actions should be takenunless benefits exceed costs. However, such argu-ments are often rejected for two reasons: First, com-plete measurements of economic efficiency, bene-fits, and costs of public actions are limited by dataand time for conducting the analysis. Therefore,a benefit/cost analysis will often not reflect alleconomic benefits and costs. Second, economic effi-ciency in resource allocation is only one of severalpossible aspects of the “public interest” which mustguide decisions. For example, the distribution ofthese benefits and costs among the public can beconsidered as important as the relative amounts ofthese benefits and costs. Nonetheless, benefit/cost

analysis is useful for comparing and screening alter-natives according to their relative contribution tothe Nation’s economy.

Implications of Water Resources Policyfor Regional Economic Development

The regional economic impact of water resourcedevelopment is an important concern that is notconsidered in ‘‘standard’ benefit/cost analysis. Tothe locality or region in which a water project isproposed, the regional economic effects may be asimportant as the costs or benefits to the nation asa whole.

Models have been developed that estimatechanges in the level of local or regional economicactivities (employment or income) and/or economicbase (development potential) due to projects or ac-tivities. Standard models include various forms ofsimple economic base studies, as well as the morecomplex input-output models.

In the past decade, advances have been madein regional development models for analyzing eco-nomic, demographic, and community effects associ-ated with water resources development. The Bu-reau of Reclamation, for example, has developedthe Bureau of Reclamation Economic AssessmentModel, an economic/demographic simulation mod-el used in both planning and impact assessment pro-cedures. Similar tools are used by the Corps of En-gineers and by regional and State water resourceagencies.

These models are used to evaluate the economiceffects of direct expenditures made in a region toimplement a program or build a project, and thecontinued effects of the spending generated by theseactivities. Such models simulate a complex and dy-namic process, accounting for multiplier effectsfrom expenditures made in direct support of theactivity (wages paid to labor, goods and servicespurchases locally, etc.), and assist in comparing theimpacts of alternative programs and projects on theregional economy. Such comparisons can be of valu-e for both planning and policy.

The use of these models is feasible for most skilledanalysts. The Water Resources Council has pub-lished multipliers developed by the U.S. Depart-ment of Commerce for simulation purposes. How-


ever, developing the models and multipliers them-selves requires special skills and extensive data.

The results of these models must be carefully in-terpreted. Such models are based on data that rep-resent the existing regional economy. If the waterresource activity being evaluated significantly altersthe region’s economic structure, the model may beinvalid. The smaller the public action relative tothe regional economy, the more reliable model re-sults will be. Moreover, these models should notbe used with the implicit assumption that economicactivity (e. g., a new industry) will be attracted tothe area solely on the basis of increased water re-sources development. Many economists considerwater projects to be uncertain means for redistribut-ing income, stimulating regional development, orachieving employment stability.

Clarification of the regional economic stake inwater development has been and can be furtheraided by careful model use. This type of analysisis best suited to planning activities, such as com-paring scenarios for different alternatives. If suchmodels are used to estimate impacts with more pre-cision, they should only assess the impact of cer-tain, direct expenditures resulting from the publicaction, and only for short (1- to 5-year) timeperiods.

Forecasting Water Use

Models for forecasting long-range water userange from simple extrapolations of past trends tocomplex models that project water use in responseto changing social, economic, and technologicalconditions.

Simple models, often termed the ‘ ‘requirementsapproach” to projection, have been favored by Fed-eral agencies in the past. These models extrapolatehistorical growth rates in water use, by use categoryor for total consumption. The models can be modi-fied to provide separate per capita use rates andpopulation projections, which are then combinedto produce a total water use projection. Under thelatter approach, per capita use is projected to growat historical rates and population projections aretaken from separate demographic studies. The re-quirements approach has been called into questionbecause it has failed to project actual water use ac-curately. The requirements approach also provides

little assistance to the decisionmaker, since it doesnot indicate why water use changes over time.

To remedy these shortcomings, more complexeconomic forecasting models have been developed.Complex models are simply applications of thewater demand models described above. First, thedemand models are used to determine the relativeimportance of the various independent factors(price, income, technology, etc. ) that determineconsumption levels for each major category of wateruser. Second, future changes in these factors areprojected and incorporated into a demand modelto predict future demands for water. A disadvan-tage of the complex model approach is that it re-quires projections into the future for many factors,a difficult task requiring a large, credible data base.

Water use projections are only guides—’ ’bestguesses’ about an uncertain future. The demandmodel approach does, however, serve a useful rolein planning and policy. Models can be used to testthe sensitivity of forecasts to different assumptions—e. g., they can identifyquences of overinvestmentwater supply capacity.

Risk/Benefit “Analysis

and assess the conse-or underinvestment in

The consideration of uncertainty in planning orpolicymaking processes is a significant recent devel-opment in water resources analysis. ‘‘Risk assess-ment, o r ‘ ‘risk/benefit analysis, is required bythe revised P&S for situations in which uncertain-ty is an essential element of the planning process.Risk/benefit analysis deals with uncertain eventsso as to reflect both the expected outcome (in aprobabilistic sense) and public attitudes towarduncertainty and risk. Public attitudes are particular-ly difficult to gage for those situations in which thereare low probabilities of highly serious accidents.

Since the year-to-year and day-to-day variabili-ty of the hydrologic cycle encourages the presen-tation of information in probabilistic terms, riskanalysis is a particularly suitable approach to waterresources decisionmaking. A flood or a drought ora pollutant spill of a particular magnitude will causequantifiable losses. Estimates of the probability ofthat size flood or drought or spill occurring trans-form the projected loss to a statement of risk. Safetyis generally paid for with time and money. Projects


and policies, with their associated costs, work toeither reduce damages or the probability of an un-desirable event. Judgments about acceptable levelsof risk and what should be spent to reduce themare a part of the politics of water resources. Modelscan help in clarifying those choices.

Risk/benefit analysis organizes information so thedecisionmaker can compare the reduced risk of al-ternative policies with the increased costs. The“benefit” side of risk/benefit analysis is generallya statement of net costs incurred by choosing a morecostly alternative over a less costly one. These costsare calculated using estimation models similar tothose used for benefit/cost analyses. The ‘‘risk’ sideof risk/benefit analysis is a statement of the proba-bility and consequences of a particular action oroccurrence. Consequently, risk/benefit analysis isnot the sole domain of social scientists, but mustrather be conducted by engineers, lawyers, and sci-entists from many disciplines.

Methods for estimating adverse health and safetyrisks are relatively new, but the cases in which thesemethods have been applied are relatively similar.One of the major shortcomings of this approach isthe inadequacy of historical data to construct prob-ability functions. Although subjective probabilitiescan be assigned by experts, such assignments canpotentially impart biases to the analysis. The highdegree of uncertainty about dose-response relation-ships, in particular, tends to reduce the credibilityof quantitative estimates of risk.

Social Impact Analysis

The potential social impacts of water resourcesprograms or projects have received increasing pub-lic attention in recent years. As a result, Federalagencies have begun to develop accounting methodsfor social-effects that consider two important factors:

1.

2.

The effects of a program or project fall un-evenly on different groups. For example, somegroups may benefit from increased employ-ment, some may experience shifts in recrea-tional opportunities, others may undergo taxincreases.The desirability of these effects will dependon the value structures of the groups affected.The impact of activities can be perceived dif-ferently by different groups.

These two factors mean that political decisionsare likely to affect certain groups differently thanothers. Decisionmakers need to understand not onlythe effects of a project, but also what the effects willmean to the affected individuals.

Regional economic development models (de-scribed above) provide a basis for considering com-munity-level effects—particularly effects on hous-ing, on the demand for public facilities and services,and on the overall fiscal condition of local govern-ments. Once these consequences of a project havebeen determined, consideration must be given towhat the Water Resources Council has referred toas ‘‘social well-being. The remaining questionsare of two kinds: First, what is the effect of the proj-ect on the social structure of an area? Second, howare the economic, demographic, community, andsocial effects of the projects perceived by the affectedpeople? Models and operational methods to answerthese questions are still in the research stage.

Current research indicates that social structureis definable in terms of: 1 ) the functional groupsin an area; 2) the characteristics of the groups (e. g.,size, attitudes towards growth); and 3) patterns ofeconomic, political, and social interaction amongthe groups (e. g., employee/employer relations andpolitical alliances). Questions can then be asked:Will a project introduce any new groups into anarea? Will it in any important way affect the char-acteristics of existing groups? Will it affect the wayin which economic, political, or social interactionoccurs among the groups? Answers to these ques-tions constitute the social effects of a project in thesame sense that economic/demographic and com-munity effects can be defined using the models andprocedures outlined above.

The next step in social well-being analysis is todetermine the significance of the changes to the peo-ple affected. This requires that the distribution ofeffects among the various groups be known and thattheir individual evaluations of these effects be deter-mined. Specifying the distribution of the effects(economic, demographic, community, social) isusually possible once both effects and groups havebeen clearly defined. Effects can then be evaluated,largely through direct questioning of group mem-bers or knowledgeable individuals. This part of thesocial assessment process constitutes ‘‘public in-volvement.


In projecting the social impacts of variouschanges, models can be used to: 1 ) organize infor-mation on the social factors that are affected, and2) qualitatively determine the direction of the im-pacts (positive, negative, or no change). Even thisqualitative information can be useful to a decision-maker. If a systematic approach is not used, theinventory of social impacts may be incomplete.

Unified River Basin Planning and Management

River basin models consider the simultaneous useof water resources and the competing values associ-ated with those uses. Such models are one meansof assessing the ‘‘value’ of water for alternativeuses—both for offstream purposes and recreational,wildlife, and water quality instream uses. Thesemodels form an analytical basis for examining alter-native planning and management strategies for anentire river basin. River basin models require in-put from a large number of disciplines as well asinformation from economic and social models.

Two principles are central to unified river basinplanning and management:

1.

2.

River basin planning stresses comprehensiveanalysis of the interrelationships among waterresources and social and economic activity,rather than the project-specific focus of mostplanning activities.River basin planning emphasizes monitoringand analyses on a continuing basis, insteadof only at times when specific projects arebeing considered.

Since the methods applied in this area are similarto, or the same as, the methods discussed in the

The first models developed for unified river basinplanning were river basin simulation models com-pleted during the 1960’s. These models linked waterresources to economic activity and demographictrends. The Susquehanna River basin model devel-oped in the early 1960’s was the first of these ef-forts, and demonstrated the applicability of a sys-tems approach to river basin analysis. The generalexample provided by that work has been repeatedmany times since.

Another related application of river basin analysishas occurred principally in the Western UnitedStates. Models have been developed to analyze theeconomic development implications of competitivedemands for water among agriculture, energy-re-lated mining or industrial development, and in rec-reational stream uses. Analysis of the implicationsof alternative allocation schemes has generally beenconducted at the river basin or State level, usingsimulation models with hydrologic, econometric,and demographic components. Models of this kindwere first developed for the purpose of analyzing

different resource management strategies in Utahin the early 1970’s with the Utah Process EconomicDemographic Model. Similar models now exist inmany States and, among other applications, areused to analyze water resource management al-ternatives.

Only in a few basins have there been modelingand data collection on the scale necessary to relatein detail both water quality and water demand tosubregions and sectors. To do this comprehensively

requires linking physical and social models that in-clude many subjective inputs from citizens and/ordecisionmakers.

previous sections, all of the justifications and limita-tions discussed in those instances apply here.

Appendixes

Appendix A

Summary of Findings From OTAWorkshops on Water Resource Modeling

During the fall of 1979, the Office of TechnologyAssessment held two series of workshops on water re-source modeling. The first series, held on October 24and 25, addressed issues raised by staff members from21 Federal agencies. The second series, held on Novem-ber 28 and 29, brought together 37 representatives ofuniversities and private consulting firms.

The two sets of workshops were identical in organiza-tion and operation. During the first day, both sets con-sidered problems in model development and applica-tion; on the second day, they considered problems inmodel management and in the use of model results. Par-ticipants in each workshop were divided into four topicaldiscussion groups: 1) surface water flow and supply;2) surface water quality; 3) ground water; and 4) eco-nomic and social factors. Each group, on each day itmet, identified a list of problems that emerged duringthe day’s discussion, and then used an idea-writing ses-sion to develop solutions to the problems identified.

This appendix synthesizes the results of the two setsof workshops. Because many of the same problems wereraised and discussed across topical groups and in bothsets of workshops, results will be summarized by prob-lem area. Concerns or suggestions specific to one of theseries or to a topical group will be so identified.

Research and Development (R&D)—Specific Areas

Participants in each of the four topical discussiongroups identified several specific research needs withintheir assigned areas. These needs are summarized be-low.

Surface Water Flow and Supply

Participants identified the following uses as researchpriorities:

● Online operations of water supply systems. Modelsneed to be developed to aid managers in determin-ing current operating rules on the basis of presentand historical flow and demand conditions.

● Prediction of regional low flows and droughts.Models for stochastic analysis of regional hydrologyneed improvement.

Surface Water Quality

Participants in both workshop series placed high pri-ority on two major research categories: 1 ) erosion andsedimentation; and 2) the fate and transport of toxicants.

For the first category, Federal participants suggestedseveral specific areas requiring model development:

● Erosion models that predict the outcome of man-agement alternatives, such as deforestation.

Models that determine the fate of chemicals beforethey reach the stream system.

● Physically based models for sediment detachment,transport, and channel erosion. Empirically basedmodels are currently being used.

● Sediment transport models linked with ecosystemmodels.

Participants agreed that improving the current stateof knowledge about toxicants is urgently needed beforebetter models can be developed to help in complement-ing major regulatory programs. Federal participants em-phasized the need to improve understanding of:

● transport mechanisms;● the long-term fate of toxic materials; and● the effects of toxics on biological organisms and

communities.Federal personnel identified two further categories re-

quiring research: reservoir and river mixing; and non-point source pollution. The group considered the firsttopic a high priority because reservoirs and rivers arereceptors of toxics, and because mixing is an importantcomponent of sediment transport.

Nonpoint source pollution was considered to be in-creasingly important, as control of this problem becomesmore cost effective than controlling point source pollut-ants. Specific model needs include:

nonpoint source models that include toxics as wel]as sediment runoff;models to predict reductions in nonpoint sourceloadings due to various control strategies;models that translate nonpoint source loadings intowater quality and ecological impacts; andmodels that qualify loadings under event-orientedconditions rather than on an annual basis.

Ground Water

Both series oi workshops advocated R&D of modelsto analyze flow through aquifers that are difficult to

165


characterize. The private sector group specifically iden-tified flow through fractured rock as a research need;one Federal participant gave the example of radioac-tive waste disposal assessment as an application in whichground water flow is a highly important component.

Understanding the transport of chemicals throughground water in order to assess concentrations of con-taminants was also identified as a research priority byboth workshop groups. Specific suggestions included:

. improving the numerical accuracy of ground watertransport models;

. incorporating chemical reaction terms into trans-port models; and

. researching the capability of aquifers to naturallycleanse themselves of pollutants.

The private sector group unanimously suggested thatthe Government sponsor research at specific waste dis-posal sites. Members suggested that this research be partof a national program to deal systematically with pro-duction, processing, and disposal of potentially hazard-ous waste.

Economic and Social

Federal representatives considered interregional mi-croeconomics to be a research priority. Participants dis-agreed about both the adequacy of economic theory andthe availability of data to describe interregional econom-ic effects. Private sector modelers focused on intra-regional concerns; specifically, developing methods toanalyze the distributional implications of water policies.They pointed out problems of cost and availability forobtaining comparable data on a regional basis, andproblems of determining the proper structure of mod-els—e. g., the proper level of geographical aggregation,and assigning relative weights to social, economic, andenvironmental concerns when characterizing the effectsof water resource activities.

R&D—Methods

Two major themes emerged from workshop discus-sions about modeling methods: 1 ) improving and char-acterizing predictive capability; and 2) integrating alter-native methods and improving their ease of use.

Methods to Measure Uncertainty

Participants in the private sector workshop stated thatresearch on quantifying the uncertainty of predictionsis needed. Specifically, they suggested that improved,standardized methods need to be developed and adoptedfor assessing the total uncertainty in model outputs dueto errors in data, sampling, model parameter estima-

tion, and calculation. Knowledge of risks policy makerswould most like to avoid would also aid in designingmethods for reporting uncertainties.

Federal participants in the area of ground water mod-eling identified a need to improve parameter estimationand methods for incorporating uncertainty into stochas-tic models. They suggested: 1) that parameter estima-tion procedures allow for interaction with the user topermit initial estimations, and to constrain the rangeof values being generated; and 2) that uncertainty ofinput and its impact on reliability or confidence in out-put always be considered during an analysis, to increasethe utility and aid in the acceptance of ground watermodels.

Risk Characterization Methods

The surface water flow and supply group in theprivate sector placed high priority on two items:developing methods to characterize both long- and short-term risk in water systems, including reservoirs; andconveying the concept of risk to the public. One par-ticipant noted that risk is relative, and asserted thatmodelers should therefore determine the cost of notmeeting some requirements when judging risk and itsimpacts. Another participant argued that this approachwould result in guessing with computer models, whichhe considered less reliable than experienced judgment.

The Federal surface water flow and supply group fo-cused on the relationships between extrapolation tech-niques and risk characterization. The group identifieda need to improve techniques for extrapolating short-term simulation results for long-term implications.These extrapolation techniques are critical for extendingthe use of available data bases.

Predictive Capability

The surface water quality group from the Federalworkshop recognized a need to make ecosystem modelspredictive at higher trophic levels. Participants statedthat development of predictive models appears stalled,even though the techniques are within the state of theart. Recently developed theory has not yet been incor-porated into predictive models.

-The same group identified a need to improve predic-tive capabilities and procedures for dealing with ‘ ‘non-predictive’ events. One participant suggested linkingstochastic models with physical models to generate longtime-series of simulated ‘ ‘data, which, along withprobability analysis, could help improve predictive capa-bilities, Probabilistic models could also be coupled withor used as complements to parametric and deterministicmodels.

App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 167

The surface water quality group was also concernedover the need to improve current capabilities to modeltransient effects.

Model Integration and Coordination

In the private sector workshops, both the surfacewater quality and economic/social groups focused on theneed to interrelate different types of modeling capacities.Participants in the surface water quality group statedthat research should be done on methods to improvecompatibility of components of water quality models.The major components of these models—sources of ma-terials, transport to and within receiving waters, andprocesses occurring within receiving waters—are mod-eled individually and independently, often at differenttimes and space scales. Research is needed to make theindividual components compatible over the longer timeand larger space scales needed for effective water qualitymodels.

Private sector economic/social modelers suggested theneed for methods to integrate their work with physicallybased models.

Higher Dimension Models

The need for two- and three-dimensional models forrivers and other water bodies was mentioned by the sur-face water quality group. One view was that for plan-ning or screening alternatives, one-dimensional modelsare often, though not always, sufficient. For design pur-poses, two- or three-dimensional models are frequentlyimportant.

Participants suggested developing a research programto determine the type of models needed for differenttypes of problems—relating the dimensionality of themodels to different water bodies and pollutants.

Methods To Improve Model Use

Workshop participants suggested several R&D areasthat might result in more efficient and productive usesof models. These include:

. using models that address a wider range of aherna-tives— this is of primary importance in economicmodels;

developing more efficient analytical methods to re-veal sensitivity relationships to the user; and

developing improved model calibration methods,including automated and user-interactive methods.

Finally, members of the private sector surface waterflow and supply group suggested that standard, acceptedmodels for routine tasks be identified and made avail-able. In addition, they advised that standard computerprograms be designed that include a set of random num-

bers already specified for comparative and reportingpurposes.

Data

One of the major concerns of both Federal and privateparticipants was that data are not available to develop,calibrate, validate, and apply models. Federal modelersidentified the intensive data needs of complex models,the cost of data collection, and the lack of coordinationand planning of data gathering as major reasons for theunavailability of data.

Private participants tended to agree that the data-gathering process should be related more directly to theneeds of models. Some suggested that modeling shouldprecede and guide data gathering. Federal participantsstressed the need for model developers to be more sensi-tive to the potential data requirements and data costsof their models, and suggested that data collection occurconcurrently with model development.

Federal participants also agreed that improved data-collection techniques are needed to facilitate more eco-nomical data acquisition. Some participants expresseda need for greater attention to the design of data net-works. Private modelers felt that the problem of inade-quate data often arises because Congress and govern-mental agencies are unwilling to conduct data collec-tion and review programs. Participants noted that manymodel types continue to be developed without adequatedata to support them. They felt that certain model typesshould not be developed without commitments to relateddata-gathering activities. However, private sector par-ticipants noted that if data collection is not funded, reg-ulations will need to be designed to accept qualitativeor semiqualitative solutions.

To improve data availability, Federal participantssuggested that developers, users, and data gatherersshould: 1) share data and identify cooperative dataneeds; 2) perform sensitivity analyses to identify themost critical data needs; and 3) develop mechanisms toidentify and collect long-term data. They also stressedthat continual reprogramming of research funds oftencauses long-term data needs to be neglected.

Existing Data Bases

Federal participants felt that it would be cost effec-tive to spend additional time analyzing existing databases. The surface water flow and supply group sug-gested that better agency coordination is needed to con-solidate existing data bases. The group recommendedthat data base management specialists be employed tomanage agency and interagency data systems.


National Data Bank

The private sector group held extensive discussionson the need for a national data bank. Speaking againstthe idea, participants stated that data banks in generalare not desirable because data collection should be donewith specific model formulation in mind. People in theground water group wanted a standard data base devel-oped for independent model comparisons. Suggestionsfor groups to manage a data bank included the Environ-mental Protection Agency (EPA) laboratory at Ada,Okla., or the Holcomb Research Institute, with fundingby EPA. Some people in the surface water group wanteda national data base to supply consistent, experimentaldata for establishing the interrelationships betweenquantity and quality parameters. In the economic/socialgroup, some members felt that an agency similar to theCensus Bureau should be established to obtain reliableand consistent water resource data.

Documentation

Federal and private sector modelers strongly believedthat inadequate documentation restricts the wide use ofgood models and contributes to the misuse of models.Participants agreed that the inadequate allocation ofresources for documentation and the lack of incentivesto promote good documentation greatly contribute tothe problem.

Federal participants suggested the following remedies:● Assign responsibility for documentation to an orga-

nizational unit to ensure that adequate resourcesare allocated. This unit might also handle technol-ogy transfer, users’ assistance, etc.

● Provide incentives to modelers to allocate time todocumentation efforts.

● Establish minimum guidelines for documentation.Private sector participants tended to advocate more

prescriptive approaches. They asserted that agenciesshould demand acceptable model documentation of allmodels developed with public funds. As an added incen-tive, agencies might withhold a percentage of the proj-ect costs until adequate documentation is received. Cur-rently, they complained, Federal agencies such as theOffice of Water Research and Technology and the Na-tional Science Foundation may end funding before thedocumentation project is complete.

Federal participants specified two separate compo-nents for adequate documentation: 1) a technical docu-ment; and 2) a users’ document. A separate programmers’document and an executive summary document weresuggested by a few participants. In the private sectorgroups, suggested components for complete documenta-tion of a model included: user’s manual; capabilities andlimitations (including explicit acknowledgments of the

failure to model phenomena that are not well enoughunderstood to be modeled); case studies and examplesrepresenting previous successes and failures; referencesto literature citations and names of people and organiza-tions who have used the model; operation costs; person-nel requirements; and a program listing and computerrequirements.

Validation/Credibility

Federal participants identified the lack of model vali-dation as one of the most important problems in waterresource modeling, and discussed three major factorscontributing to the problem.

First, resources are not adequately allocated for modelvalidation because of its high costs. These costs mightbe reduced if interagency cooperation increased (e. g.,cooperative interagency sampling and funding arrange-ments).

Second, the lack of necessary data for validation re-quires attention. The cost of data collection, the absenceof historic data, and the time necessary to collect valida-tion data are all limiting factors.

The third factor was the absence of guidelines for val-idation, identified specifically by the surface water flowand supply group. A majority of the group supportedguidelines, while recognizing that guidelines would bedifficult to establish because of the diversity of modeldesigns and applications. A lead agency might be givenresponsibility for suggesting appropriate guidelines.

The private sector groups advocated establishing ap-propriate incentives for validation. Other suggestionsfrom the private sector focused on specific proceduresfor model validation, requiring sensitivity analyses onall analyses made, and requiring followup investigationwhere model scenarios have been implemented.

Participants from the private sector also felt that mod-els should be subject to peer review. They suggested thatagencies contract for intensive review in key projectstages, such as definition, completion of model develop-ment, and review of results.

Technology Transfer and Training

The majority of participants in the Federal workshopconsidered improving technology transfer to be a toppriority; private sector participants agreed that appro-priate technology transfer and Federal agency policieson technology transfer do not currently exist.

While most Federal participants believed that respon-sibility for technology transfer lies with the model devel-oper, they also recognized that agencies need to pro-vide adequate resources for technology transfer pro-grams. They suggested that proper allocation of re-

App. A—Summary of Findings From OTA Workshops on Water Resource Modeling “ 169

sources might be expedited if responsibility for technol-ogy transfer were given to a lead agency. Modelers fromthe private sector suggested that for agencies currentlywithout technology transfer mechanisms, either in-housedevelopment or outside contracting would be appropri-ate.

Private sector participants tended to focus on train-ing in specific disciplines and related model use as animportant component of technology transfer. Partici-pants mentioned the federally supported universitytraining grant programs in environmental pollution andenvironmental health (now discontinued)—a compar-able training program in water resources is neededtoday. They felt that funding universities to transfer newdevelopments to the agencies should continue.

Participants from Federal agencies made a numberof suggestions regarding particular methods of accom-plishing technology transfer. Most agreed that the mostimportant mechanism is one-to-one interaction betweenthe user and the developer. For example, developersmight be temporarily assigned to a user’s organizationto assist the user, and in addition, provide feedback forthe developer. Using a central technical support staffto help solve operational problems was also suggested.

Workshops that give participants “hands on” interac-tion with models, and seminars, were considered goodtransfer techniques, especially if the developer is directlyinvolved. Workshops and seminars designed for differ-ent levels of users (e. g., managers, technical specialists,modelers, and laymen) were also deemed necessary.

Generally, Federal participants believed that agen-cies need to develop incentives for developers to investtime in technology transfer activities. Many acknowl-edged that current agency career evaluation systemsdiscourage modelers from providing adequate technol-ogy transfer.

Model Maintenance

Both Federal and private workshop participantsstrongly believed that adequate model maintenance isessential for effective model use. Private sector partic-ipants specified that Federal funding should be providedto support model maintenance and updating, but dif-fered in their views on appropriate institutional arrange-ments to provide such support. Proposals included:

●

●

●

designating a lead agency to track and disseminateFederal model information and revisions;requiring the sponsoring agency itself to maintainand update the model; andhaving the agency provide funds to the developer(or other outside group) to maintain and updatemodels.

Federal participants proposed several specific methodsto improve model maintenance:

establish minimum guidelines and standards formodel maintenance;prepare a written plan for long-term maintenanceand assurance of adequate resources to undertakesuch maintenance. Year-by-year requests are in-appropriate;assign responsibility for model maintenance to anorganizational unit and assure that appropriate re-sources are available to carry out this goal. Thisgroup might also be responsible for model docu-mentation, user assistance, and technology trans-fer; andestablish an interagency clearinghouse to conducta periodic survey of models, and to update and/orrevise model components as needed.

Clearinghouse

Perhaps the most controversial of the subjects ad-dressed at the workshop series was the concept of a clear-inghouse for information on available models. Most par-ticipants in the private sector agreed on the utility ofsome form of a model clearinghouse; Federal modelersin the surface water quality and surface water flow andsupply groups classified the concept as one of their 15priority categories. The latter groups stated that a clear-inghouse or inventory is needed to aid technology trans-fer and to serve as an information source for effectiveplanning for future model development.

In the Federal workshop, the clearinghouse conceptwas conceived as having various possible levels of opera-tion. At the simplest level, a periodic inventory mightbe established—e. g., a central catalog of models by sub-ject area, listing available models, the agencies that usethe model, and a contact person or agency. While suchan inventory might be adequate, it would likely be dif-ficult to administer.

A fully established clearinghouse could offer severalextra services. The participants felt that responsibilityfor the clearinghouse should be assigned to either an in-teragency group or a particular agency. The clearing-house could assist future model development by actingas a focal point for the questions of both developers andusers. It could help to isolate needs for cooperative stud-ies and determine areas of duplication.

Some Federal participants felt that technical litera-ture, conferences, and professional meetings could ade-quately serve the same function. Other participantsstrongly believed that these mechanisms were not suffi-cient, partly because some operational agencies seldompublish their modeling efforts. Additional skepticism was


expressed about the cost effectiveness of the clearing-house approach.

Private sector modelers who opposed the idea assertedthat it might cause centralization, resulting in red tape,regulation and ineffective action; and siphon limitedfunding that could be better spent elsewhere.

Coordination

Participants in both sets of workshops concurred onthe lack of coordination of resources and informationfor model development among Government agencies.Private sector participants, while dismissing the issueof duplication as a minor problem, proposed better re-gional and interagency cooperation to improve coordi-nation. Federal modelers noted the lack of mechanismsto promote interagency efforts, and the absence of incen-tives or precedents for agencies to work together.

Federal participants suggested a number of mecha-nisms for improving interagency coordination:

●

●

●

a national clearinghouse and periodically publish-ed information directory to provide users withinformation about the quality, availability, andcharacteristics of models;an interagency model development review commit-tee. This responsibility might be assigned to an ex-isting committee. Some participants felt that thecommittee should have only an advisory role, fear-ing infringement on agency and scientific freedom;anda centralized source of expertise to advise on inter-agency data base creation.

Questions arose as to the practical value of some ofthe suggested mechanisms in view of the diversity ofagency needs. Coordinating efforts through interagen-cy meetings were considered to be too broadly philo-sophical to aid with actual development. However, par-ticipants recognized the importance of avoiding newmodel development when an existing model can be mod-ified to serve the same purpose.

Educating Managers andDecisionmakers

The need to educate management and decisionmakersto the capabilities, assumptions, and limitations of mod-els was stressed by participants in both workshop series.Private participants emphasized the importance of dem-onstrating to managers/decisionmakers that models aresimply tools that provide information and insight, ratherthan solutions. Federal modelers were concerned aboutthe loss of credibility suffered by models as a result ofpoor user understanding. They noted that users’ lackof understanding of key concepts leads to model misuse

and distrust of good models. User understanding wasconsidered especially important for economic models,because they cannot be easily validated. In this case,it would be very important for the user to understandmodel construction in order to have confidence in themodel.

Workshop participants felt that managers/decision-makers must be provided with the following infor-mation:

●

●

●

●

the underlying conceptual basis of models (ratherthan detailed mathematics);a taxonomy of resource models matched to a cor-responding taxonomy of resource problems;the relative uncertainty of different models’ results;andalternative ways to use models to solve ‘‘ real-world’ problems.

Responsive Model Selectionand Development

Federal and private sector modelers concurred in con-sidering the selection and development of inappropriatemodels a major problem, and in the need for modelersto pay greatest attention to policymakers’ needs and ob-jectives in selecting/developing appropriate models. Oneparticipant estimated that 75 percent of all models arecreated without a suitable set of specifications definedby the problems toward which they are directed. Federalparticipants further emphasized the need for users tounderstand their own needs and the limitations andassumptions of the models they consider.

Users often want quantitative answers to specificmanagement questions and issues. However, accordingto Federal participants, the users may be unsure of whatinformation is necessary or may perceive that modelshave greater capabilities than they actually do. In gen-eral, good documentation can help users understandmodel capabilities. The participants suggested severalspecific mechanisms to help users gain a better under-standing of what models exist and how these models canbe used to solve specific problems:

● Summary documents listing models available ineach agency. These documents would briefly de-scribe operational and developmental models andtheir assumptions, capabilities, limitations, appro-priateness for specific applications, and the devel-opers’ names and phone numbers. These docu-ments could stress the specific questions that avail-able models can address.

● Seminars for users in each agency on state-of-the-art modeling efforts.

A final recommendation from private sector modelerswas that repeated interaction between modelers and pol-

App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 171

icymakers is necessary to respond to new objectives andproblems suggested by model results. Federal partici-pants suggested a number of specific mechanisms foraccomplishing these interactions. To develop general-purpose models, the participants recommended usingmodern group management techniques to solicit theneeds of potential users. For more specific models, im-proved communication between users and developerswas considered necessary. Several participants suggestedpredevelopment working sessions to help modelers de-termine users’ needs and help the users understand whatmodels can provide.

Legal and Regulatory Problems

Problems mentioned by conference participants fromthe private sector in this category ranged from legal lia-bilities associated with the use of models to interjurisdic-tional disputes over model use. Participants suggested

that agency contracts be more specific concerning thelegal liability of the model developer.

Conflict among Federal, State, and local decisionsbased on the use of different models was also considered.Communication and cooperation among agencies, in-cluding joint model development, was suggested to alle-viate these problems. However, participants also notedthat different and conflicting laws, delegations of author-ity, and organizational interpretation of laws and modelscontribute to interjurisdictional disputes.

Participants from the private sector emphasized thatregulations should not require specific methods. Manythought that models used in regulatory applicationsshould stress objectives, not specific methods. Othersthought that models used in regulatory applicationsshould be required to undergo peer review and valida-tion. Another suggestion was to establish a continuously

reviewed listing of models appropriate for certain regu-latory applications.

Appendix B

Summary of Model Use byIndividual Federal Agencies

Introduction

This appendix summarizes water resource modelingactivities of Federal agencies, using information suppliedby the agencies and reviewed by OTA contractors andstaff. The information was obtained from three sources:participants attending an OTA workshop, selected in-terviews with agency personnel, and a survey requestingagencies to indicate their model use under specific waterresource laws. Agency representatives to the OTA work-shop on Federal agency model use provided OTA witha written description of their agency’s model use andmodel documentation, when available. Further informa-tion about model use and model documentation was ob-tained through selected interviews with agency person-nel. The survey yielded information on legislation-related model use in Federal agencies as of June 1980,for agencies and ofllces in existence at that time (see sur-vey form, attachment II).

This appendix describes, by agency, the water re-source programs in which models are used and the typesof models generally employed. The summary table ofagency model use (table B-1 ) provides an overview ofthe water resource modeling activities of most of theagencies discussed in the text. The 33 water resourceissues used to construct the table are listed in their unab-breviated form in table 1 of chapter 2. References forthe text are listed by agency in attachment 1.

U.S. Department ofAgriculture (USDA)

Economics and Statistics Service (ESS)

ESS provides economic projections of short-term andlong-range agricultural demands for land and water re-sources. Its analyses focus on how alternative develop-ment of such resources could affect the agricultural andrelated sectors of the economy. ESS responsibilities in-clude basinwide and interregional economic aspects ofcomprehensive river basin planning.

ESS is involved in programs under the Federal WaterPollution Control Act of 1972 (Public Law 92-500), asamended by the Clean Water Act of 1977 (Public Law95-217, hereinafter referred to as the Clean Water Act);the Soil and Water Resources Conservation Act (PublicLaw 95-192, hereinafter referred to as the Resource

Conservation Act); and the Water Resources PlanningAct (Public Law 89-80). It uses models in each programarea.

Under section 201 of the Clean Water Act, whichdeals with construction grants for treatment plants, ESShas used models to assist local groups in Pennsylvaniain choosing among alternatives for treatment facilities.ESS also uses these models as part of its own generalresearch and development effort. For its programs inareawide waste treatment management planning, undersection 208 of the act, ESS has developed a large policymodel to evaluate alternatives for improving water qual-ity in the San Joaquin Valley in California. Among thefactors the model considers are land-use options, zon-ing, and application of irrigation water. ESS uses modelsunder section 209 of the act as well, which addressesnationwide river basin planning. Models are also usedto determine the minimum cost of comporting sewagesludge in evaluating different projects under section 405(disposal of sewage sludge) of the Clean Water Act.

ESS is also involved with regional or river basin plan-ning under section 102 of the Water Resources Plan-ning Act. The service uses models to estimate economicimpacts of section 102 programs (regional or river basinplans). The models help project future economic condi-tions in rural areas under various scenarios. As is thecase with all USDA river basin studies, these studiesare carried with the cooperation of local sponsors.

In planning conservation programs under section 6of the Resource Conservation Act, ESS uses models toproject the likely effects of different economic conditionsand conservation programs on land and water use, onerosion, and on the national economy.

ESS develops and applies computer programs for suchother agencies as the Soil Conservation Service, the Wa-ter Resources Council, and the Environmental Protec-tion Agency (EPA). These models generally incorporateeconomic criteria and are often of the optimizing orprescriptive type. An increasingly important service ofESS is to maintain the Land and Water Resources andEconomic Modeling System (LAWREMS) described inchapter 4 of this report. This directory aids commu-nication and technology transfer among agencies inorder to reduce duplication in model development.LAWREMS contains models and data sets developedand maintained by ESS and other agencies and non-governmental bodies.

172

App.

B—

Sum

mary

of M

odel U

se by

Individual F

ederal A

gencies ●

17

3

GWYum

a3P3znsII

Water resource of Q:c:.l1~C: ESS

~ M I" -_. <- --_... ..... --_. --, 0

r-;

T rtrnl1aht"JlntJ ~lntJ rnr~("'.::tR.r

.--i I-< Q) ~ '0 streamLlow reQ:ulat10n U ~ ~ I i nQ t-rp;:!m f 1 nw nPM R C1l ~ !:Ij ~ Ul

i1nmgcr-1r-

~ "I Qllnnlv ~ ~

'" ,..,...; rrnt-.o.A ftlT .... ; ".111 ~,"_a r.Il 0 Q) .--i UJ ~ ::J I nr rRrrp;:!m l1RP

ettlclenc~ and conservat10n IlTM n TlInnf f

" 1-'< wl·rno.nn < o,.'=n',"nn Q) o::s .j.J 0."-; H~LV C1l :>, p..-; ~ .j.J 0 0 ;:!O'ri 1',,1 t"l1r.,l rl1nnf f

• .-i za...

C1l ~,~ ~ tJ'i+J 1-1 ~ r.Il

8 o p o u w

,-.-i r-; ~ :l 0'

~ +J P 0' I-Ir-

C.J ~ .j.J+J cU-,-I ~r-;

~ :l 0'

u -,-I

8 a p a u t.]

I~

!!I ... .,..hnY'"no nnl 111~!:In""C!

waste load allocation m

rna nld g

imnAC'.t:A nn AnIlAt:iC'. li fp

ava~~aD~e supp~y

"'l"\n""1;1"", ... -I",o uClA

nT' nK' nl7 w;:!rPT nll::ll' I:V gr po

me po

ru

cost ot nollutlon control benefit/cost anal~sis

8I -F,..,. ..... a_n,r,+-.f rllT ... __

SOCl.al 1moacts r.l.HK.1 rv>nprll: ::Ina..1.VQl Q r omn~r-1 r 1 UQ .,ag t1gm.anrlc:.

_1 ....... _ ---~- ma--------

Table B-1 - Federal Agency Model Use - January 1981

National Forest Weather Corps of Bureau of Sprvic~ SEA S S Service Emdneers DOE FWS Reclamation USGS CEQ EPA WRC

y y y y y y x x To. To. To. A LI..

x x x X I\.

X X X X x x X To. To. LI..

Y Y Y Y Y To.

To. To. A A- Il.. A

x x x X I\. I\.

X X X X X X X X X X X X X

LI.. LI..

X X X X X X X

X X X X X X X -- -- --

X X X X X X X X X

A I\. A LI.. LI.. LI.. .l\.

X .l\. A A

X X

X X X X X X X X

V Y Y Y x

x I\. I\. LI..

LI..

To. A A A A


Forest Service

The Forest Service is responsible for developing, man-aging, and protecting lands in the national forest system.Its objectives include fostering multiple use and sus-tained yield of forest and rangeland resources. Beyondits research and data-gathering functions, the ForestService coordinates planning for the forest~ componentof river basin surveys and investigations, as well as forthe small watersheds program under the Watershed Pro-tection and Flood Prevention Act (Public Law 83-566).It is also responsible for managing flood plains and pro-tecting wetlands on national forest system lands.

The Forest Service carries out a large number of pro-grams authorized under water-related legislation, anduses models in connection with many of these programs.These include:

Under the Clean Water Act:● section 107—mine-water pollution control;. section 208—areawide waste treatment;● section 209—river basin planning;. section 303—water quality standards and imple-

mentation plans; and. section 3 14—clean lakesoUnder the Endangered Species Act (Public Law

93-205):● section 7—minimizing impacts of Federal activities

modifying critical habitats.Under the Surface Mining Control and Reclamation

Act (Public Law 95-87):. section 506—surface coal mine reclamation per-

mits; and● section 51 5—environmental protection perform-

ance standards for surface coal mine reclamation.Under the Resource Conservation Act:● section 5 —collection of data about soil, water, and

related resources; and. section 6—soil and water conservation programs.Under Executive Order No. 11988:. sections 5 and 6—flood plain management.Under the Water Resources Development Act of 1974

(Public Law 93-251):● section 73—planning nonstructural measures.Under the Flood Control Act of 1936 and amend-

ments (33 U.S. C. 701, et. seq.):. sections 1 -3—choosing and designing flood control

structures.The Forest Service provided detailed information on

models used under the Forest and Rangeland Renew-able Resources Planning Act of 1974, as amended (Pub-lic Law 93-378). Under this act the Forest Service cre-ates and implements long-range land and research man-agement plans at local, regional, and national levels.Models are used to estimate changes in water qualityand supply under alternative management practices,

and to project the economic effects of such managementpractices on localities. Models also aid in determiningNational Forest Management Act regulations—themodels are used to analyze potential standards andguidelines and compare results of their applications.

Under planning activities mandated by the Forest andRangeland Renewable Resources Act of 1978, the For-est Service uses models to compute soil moisture andstreamflow in forests and rangelands. Information onsoil moisture is used to determine whether and whento plant trees, and to determine viable levels of livestockper acre of rangelands. The effects of timber harvestingon streamflow are evaluated using water yield models,which determine the maximum levels of harvest consist-ent with preventing excessive peak flows in rivers. Mod-els are also used to determine harvest designs which in-crease the water yield in watershed areas.

Science and Education Administration (SEA)

SEA is actively involved in water resources model-ing as part of its mission in natural resources research.The agency’s water resource modeling activities em-brace a wide range of topics: climate and weather, thehydraulics of overland and channel flows, rill and in-terrill erosion, sediment yields from agricultural water-sheds, infiltration, evapotranspiration, irrigation sched-uling, subsurface drainage, and the transport of agri-cultural chemicals, among other topics.

In its program under section 208 of the Clean WaterAct, SEA uses models to estimate the effects of land-use practices on agricultural nonpoint source pollution.This information is made available to USDA ofilces andto the public through USDA technical assistance pro-grams. The agency also uses water resource models inthe agricultural research it conducts under section 1402of the Food and Agriculture Act of 1977 (Public Law95-1 13). Models are used to predict the effects of differ-ent land-use practices on agricultural and nonpointsource pollution.

SEA extramural funds are used for scientific researchat universities to assist in developing water resourcemodels for resolving local, State, and regional water andwater-related problems. The research may producecomponents and mathematical techniques for use in de-veloping models or in checking the scientific validity ofmodels. SEA scientists coordinate these research effortsamong the respective States and the intramural researchprograms of SEA. In a number of cases, State and Fed-eral scientists are cooperating on the same regional proj-ect, working on mutually developed objectives, andsharing ongoing research progress at least annually.

For the most part, SEA’s modeling program aims toimprove understanding of the fundamental physical,chemical, and biological processes that control or con-

App. B—Summary of Model Use by Individual Federal Agencies . 175

strain crop production; assist resource conservation; andreduce present or future impacts of agricultural activitieson the environment. In selected areas such as erosionand nonpoint source pollution, model development hasreached the point that applying the models to resourcemanagement, planning, and policymaking is consideredboth feasible and justified. Examples of these modelsare the Universal Soil Loss Equation (USLE) model,and the Chemicals, Runoff, and Erosion from Agricul-tural Management System (CREAMS) model.

Soil Conservation Service (SCS)

SCS is authorized to develop and carry out a nationalsoil and water conservation program in cooperation withlandowners and operators and local, State, and Federalagencies. Its programs assist farmers, ranchers, andState and local organizations to prepare plans for re-source management, including structural and nonstruc-tural improvement for flood protection, water conser-vation, use and disposal of water, agricultural pollutioncontrol, environmental improvement, and rural com-munity development.

SCS has a background of mathematical modeling dat-ing back to the 1950’s. It has applied models to floodand irrigation water control and to erosion and sedimen-tation problems. The principal physical models deallargely with hydrologic phenomena: generation of hy-drography; flood routing; calculation of areas, eleva-tions, and frequencies of floods; and the mechanics ofirrigation. One model is devoted entirely to applicationsof the universal soil loss equation, although this function-al relationship also appears in many other models.

Recently, several models for economic evaluationhave been developed. In fact, approximately one-halfof the 30 models SCS currently uses are physical/eco-nomic integrative models that serve as planning toolsto help evaluate and select conservation strategies. Theyare used, for example, to project floodwater damage tourban and agricultural areas, and the costs and benefitsof various cropping, conservation, and land-treatmentmethods.

SCS reported model use under a number of legislativemandates. Under the Rural Development Act of 1972(Public Law 92-419), the agency uses models to assistqualified local sponsors in initiating and sponsoring re-source conservation and development areas.

Through the Watershed Protection and Flood Preven-tion Act (Public Law 83-566), SCS has primary respon-sibility for USDA’s cooperation with local organizationsin small watersheds throughout the Nation, and has spe-cific responsibility for flood prevention measures. Tocarry out these responsibilities, two types of models areused—a management information model and models todetermine the effects of water quality projects. The first

type is a System of Watershed Automated ManagementInformation (SWAMI), used to evaluate present pro-grams and assess needed changes.

SCS river basin and area planning activities use mod-els for planning and evaluating the physical, environ-mental, and economic aspects of water resources. Mostactivities include an inventory of existing resources,projections of future resource uses, and the evaluationof alternatives. Some studies develop specific models torepresent unique physical processes where no existingmodel can be used.

Other programs involving model use that are author-ized

●

●

●

●

●

●

under water-related legislation include:The Rural Clean Water Program (Public Law96-108), which uses models to evaluate the qualityand quantity of runoff from agricultural watershedsand to evaluate alternative systems of best man-agement practices.The Resource Conservation Act (Public Law95-192), under which models are used to predictthe effects of conservation programs on erosionrates and land and water use.The Clean Water Act (Public Law 95-217; sec.208j), under which models are used to determinethe effects of conservation practices on nonpointsource pollution from agricultural land.The Colorado River Basin Salinity Act (Public Law93-320), under which models are used to determinethe effects of irrigation practices in specific areason salinity levels in the Colorado River Basin.The Flood Control Act of 1950 (Public Law81-516), under which models are used to select anddesign floodwater-retarding structures built underthis authority.Floodplain Management (Executive Order No.11988), under which models are used to delineateflood plains and to predict the river stage effectsof different levels of flood plain encroachment.

Department of Commerce

National Oceanographic and AtmosphericAdministration (NOAA)

NOAA uses models extensively to support its numer-ous activities under current water resource legislation.Under the Clean Water Act, for example, NOAA’s ac-tivities in basin planning, secondary treatment re-quirements, water qualty standards, standards forpretreatment of toxic effluents, and clean lakes (sees.219, 301, 313, 307, and 314, respectively) all involvesome model use. NOAA also uses models in its soil andwater programs under the Resource Conservation Actand in its programs under the Water Resources Plan-ning Act.


Information from NOAA models is also supplied toFederal agencies concerned with fish and wildlife habitatprotection under the Fish and Wildlife Coordination Act(16 U.S.C. 661). These models help project effects onfish and wildlife habitats when planning or evaluatingprojects. NOAA also uses models under sections 101and 102 of the National Environmental Policy Act(Public Law 91-190). Models are used to estimate ef-fects on instream flow, evaluate effects on habitats andon an ecosystem’s trophic relationships, and predict theprobable dispersion of an oil spill.

NOAA’s hydrologic service programs are managedby the National Weather Service (NWS) under author-ity of its Organic Act ( 1890) and the Flood Control Actof 1936($ 1,2,3j, 15 U.S. C. 313, 33 U.S. C. 706). NWSis responsible for issuing weather and river forecasts andwarnings. Federal, State, and local agencies rely heavilyon NWS for river and flood information for manage-ment planning, and for probable maximum precipita-tion estimates used in designing river and flood controlstructures. NWS hydrologic forecasts are important forreservoir operations, water supply management, naviga-tion, irrigation, power production, recreation, and waterquality management. Most of the information suppliedis output from models.

The agency’s concentrated ongoing effort to imple-ment a system of interrelated mathematical models andpredictive techniques is known as the National WeatherService River Forecast System (NWSRFS). The systemincorporates models already in use and new hydrologicforecast techniques. Included are models of snow accu-mulation and ablation, soil moisture, streamflow rout-ing, and unsteady open channel flow. The system alsoincludes programs for handling and processing data andfor model calibration and verification. Planned additionsto NWSRFS are an enhanced reservoir operation mod-el, and an extended streamflow prediction technique forwater supply forecasting based on a conceptual water-shed model. The extended streamflow prediction tech-nique will eventually complement the current water sup-ply forecasting procedures, which are based on statisticalmethods.

The first version of NWSRFS was implemented in1971 and used for river forecasting in the lower Missis-sippi River basin. When fully implemented, NWSRFSwill be used by all 13 NWS River Forecast Centers(RFCS) in preparing daily streamflow forecasts for morethan 2,500 river forecast points and drainage areas cov-ering approximately 97 percent of the United States.

Department of Defense

U.S. Army Corps of Engineers

The Corps of Engineers is authorized to investigate,develop, conserve, and improve the Nation’s water andwater-related land resources. Its programs include plan-ning and development activities for protecting navigablewaters, flood control, hydroelectric power production,flood damage reduction, flood hazard information,urban land drainage, wastewater management, shoreand beach restoration and protection, fish and wildlifeconservation, outdoor recreation, aquatic weed control,and environmental protection. These responsibilities in-clude consideration of the economic, social, and en-vironmental impacts of public works alternatives.

The Corps’ mandates are based on a wide variety ofwater-related legislation and many are carried out withthe use of models. Under the Clean Water Act, theCorps uses models to help evaluate costs and designsfor water treatment facilities proposed for Federal fund-ing pursuant to section 201 of that act. The Corps alsouses models under section 1444 of the act (Federal facil-ity pollution control).

The Corps employs models in its water resource plan-ning activities. It uses models in its regional or riverbasin activities under section 102 of the Water ResourcesPlanning Act (Public Law 89-80) and in planning andevaluating nonstructural measures under section 73 ofthe Water Resources Development Act (Public Law93-251).

The Corps makes major use of models in connectionwith its flood control and management function. Modelsare used in designing and selecting flood control struc-tures to be built pursuant to the Flood Control Act andin planning or evaluating flood-control projects. Themodels help assess flood peaks, compute water surfaceprofiles, and supply data for flood damage assessment.The Corps also uses models to assist the Federal Insur-ance Administration in conducting flood insurance stud-ies under the Flood Control Act.

The Corps’ flood plain management programs underExecutive Order No. 11988 also make use of models.Models are used to delineate the 100-year flood plainso that Federal and non-Federal interests may complywith current regulations. For example, one regulationrequires that flood plain encroachment should not resultin an increase in water surface elevation of more than1 ft. The models help predict the relationship between

App. B—Summary of Model Use by Individual Federal Agencies ● 177

extents of encroachment and the rise in surface watersurface elevation.

The Corps’ research and development in water re-source modeling focuses on solving field problems. Inhydrologic analysis, the Corps’ Hydrologic Engineer-ing Center (HEC) has developed a number of computermodels for evaluating the expected magnitude and fre-quency of runoff from urban and nonurban watersheds.The principal urban runoff models are HEC-1 andSTORM. HEC models have also been used to improvethe operation of reservoirs during floods. Both HEC andthe Corps’ Waterways Experiment Station (WES) havedeveloped several models relating to river mechanics.These models simulate hydrodynamic and sedimenttransport processes in rivers, lakes, and estuaries. TheCorps’ WES and the Coastal Engineering ResearchCenter (CERC) have also developed and applied variousmodels to compute hurricane surges and wave heightsfor design and planning purposes.

HEC has developed two reservoir-system analysismodels: HEC-3 and HEC-5. These are multipurposereservoir operation models used in planning and oper-ating reservoir systems for flood control, hydropower,and water supply. The models have been used at theplanning level to evaluate the water-supply performanceand hydropower potential of existing and proposed res-ervoirs, and to study flood control. The HEC-5 modelis currently being used in operational studies of hydro-power sites selected from the Phase I screening of theNational Hydropower Survey. The Corps also usesmodels to assess the potential impact of a partial or com-plete dam failure.

Both HEC and WES are developing water qualitymodels. These models are applied to proposed Corpsprojects to predict overall water quality conditions andto develop appropriate design and operational criteriafor attaining desired water quality levels. Models arealso used to evaluate design of operational modificationsfor projects in which water quality problems exist.

The Corps’ water resource planning models focus onflood control. Flood-damage computation proceduresare part of several of HEC flood forecast and controlmodels. These procedures evaluate the expected damagefrom a series of flood events, with and without variousproposed management measures. An optimization rou-tine in the HEC-1 model analyzes various sizes andcombinations of flood-control measures and allows forthe evaluation of tradeoffs among facilities, perform-ance, and cost. The HEC interactive nonstructural anal-ysis model focuses on analyzing and formulating flood-damage reduction measures other than traditional con-struction projects.

Department of Energy (DOE)

Office of Environmental Assessments

Within the water resources area, DOE’s OffIce of En-vironmental Assessments is concerned with the impactsof energy technologies on water resources, including theeffects of energy-related pollutants on biological systems.The office is also involved in defining water and landresource requirements for energy technologies includingcoal gasification, coal liquefaction, uranium enrichment,geothermal development, small-scale hydroelectric de-velopment, enhanced oil recovery, and shale oil produc-tion.

The majority of the water resource models DOE usesare deterministic simulations of physical systems, andthey deal primarily with three subjects: assessing sur-face water supply related to the potential for energyfacilities development; analyzing energy-related envi-ronmental impacts including thermal effects and trans-port of various pollutants; and determining the econom-ic and social effects of water use for energy development,

The Ofllce of Environmental Assessments uses severalwater resource models. The Water Assessment System(WAS), located at Oak Ridge National Laboratory, isused principally for large-scale regional impact assess-ments. This model projects variations in streamflow,water use, and water availability over time to assesswater availability for various energy scenarios. The basicgeographic unit is the Water Resources Council (WRC)aggregated subregion (ASR) level. In support ofWAS, the Automated Downstream Accounting Model(ADAM) calculates cumulative water availability andconsumption data for surface streams in hydrologicsequence.

The Water Use Information System (WUIS) of Han-ford Energy Development Laboratory is used for a num-ber of DOE assessments. This is a computerized infor-mation system containing comprehensive data on waterresources, on water availability and quality, and on elec-trical generating plant characteristics and operationalcharacteristics relating to water use. Its basic geographicresolution is the WRC cataloging unit. The Los AlamosCoal Use Modeling System (LACUMS) incorporateswater supply and demand sectors into a linear program-ing model of energy supply to facilitate water- andenergy-related policy analysis. Water S UPP IY is ac-

counted for by coal demand regions.For large-scale water quality impact assessments,

Argonne National Laboratory has de~eloped the Ar-gonne Water Quality Accounting System (AQLJAS), anew regional screening model. The model utilizes


streamflow data, measured water quality data, and re-sidual discharge data at the accounting unit level to esti-mate changes in concentrations of selected pollutants.These several models are used by other agencies andorganizations within and outside of DOE.

The Strategic Environmental Assessment System(SEAS) is not a water resource model per se, but it cal-culates wastewater residuals and regional water use forenergy scenarios during the course of general environ-mental assessments. DOE has supported Fish and Wild-life Service development of an instream flow calcula-tion system to quantify the effects of water consumedby the energy industry and to determine the effect onaquatic species, habitat, and the like. Its purpose is toestimate instream flow requirements that might con-strain energy development.

Aquifer modeling, though not a major program, isbeing developed to investigate the migration of pollut-ants, particularly radioactive materials, from waste-disposal sites. Energy storage in aquifers has also beenmodeled to determine geothermal reservoir dynamicsin support of this energy source. Other models investi-gate the effects of thermal energy releases on localizedmeteorology —including effects on rainfall and cloud for-mation—which could influence water supply.

Federal Energy Regulatory Commission (FERC)

FERC in DOE uses models under two major pro-grams of the Federal Power Act (16 U.S.C. 803(f)):Dam Safety and Headwater Benefits.

A number of models are used to plan or evaluate proj-ects under the Dam Safety Program. Some determinewater surface profiles and downstream water velocitiesresulting from a dam break. Other models are used forpreparing flood hydrography, reservoir routing, and de-sign analysis.

Payments under the Headwater Benefits Program aredetermined with information provided by models. Thesemodels are used to determine the energy gains at down-stream hydropower plants resulting from the operationof headwater reservoirs.

FERC also indicated model use for its cooperative ac-tivities program under the Water Resources PlanningAct, and for its participation in planning Federal waterresources projects under the Flood Control Act of 1936and amendments. Models are used to plan, evaluate,and review projects, and for data acquisition, statisticalanalysis, and water resources/hydropower system anal-ysis.

Department of the Interior

Bureau of Land Management (BLM)

BLM is responsible for managing, conserving, anddeveloping 174 million acres of publicly owned land inthe 11 Western States and an additional 162 millionacres in Alaska, BLM also administers the subsurfaceminerals underlying approximately 370 million addi-tional acres throughout the Nation managed by otheragencies or owned by private citizens, and on the 1.1billion acres of Outer Continental Shelf owned by theFederal Government.

BLM’s use of computer-based resource models is oc-casional, and is confined to selected models for site-specific analyses. Stochastic hydrologic models are usedto evaluate alternate grazing systems in preparing graz-ing environmental impact statements. Hydraulic modelsare used to evaluate instream flow needs for adjudicatingwater rights, designing fishery habitat improvementsand water facilities such as dams and water distribu-tion systems, and in analyzing overburden materialsassociated with surface mining. In addition to thesemodels, BLM uses technological guidelines developedthrough the use of hydrologic models to analyze variousresource problems, including timber harvesting andplanting techniques and their impacts on water quanti-ty and quality; fishing improvements associated withspawning areas; flood plain identification; soil erosion;analysis of potential mineral leasing tracts; and the sitingof campgrounds associated with water-based recreation.

BLM currently contributes financially to researchwithin USDA and the Department of the Interior, aswell as to various university investigators. These re-search projects are expected to produce a series of waterresource models that will be used on a continuous basis,and to develop an additional technological guideline toaddress routine multiple-resource problems. In addition,BLM expects to continue to use models developed byothers for solving problems related to public lands.

Bureau of Mines

The Bureau of Mines’ principal responsibilities areto develop mineral resources, promote mine safety, andmaintain healthful working conditions and environmen-tal quality in the mineral industries. The bureau is con-cerned with the quality of water discharges in all phasesof mineral production, and it engages in research to de-velop and improve mining technology, including meth-


ods of protecting water resources used or affected bymining.

The bureau uses models in two of the programs it car-ries out related to the Clean Water Act, section 107,which authorizes mine-water pollution control demon-stration projects. Models are used to predict the effectsof iron ore mining in the Mesabi Range of Minnesotaon the area’s hydrologic system. Another program in-volving model use is designed to develop managementpractices to minimize water quality problems during andafter open pit mining of copper ore in Arizona. The in-formation these models generate is furnished to miningcompanies to help them comply with mine-water pollu-tion regulations.

The bureau also uses models in several other pro-grams concerned with the effect of mining on waterquality. These programs stem from various acts deal-ing with water resources:

Under the Safe Drinking Water Act (Public Law93-523), section 1421 —the bureau has used modelsto help predict the effects of surface coal miningon the ground water regime of western Tennessee.This information is made available to mine opera-tors to aid them in complying with existing regu-lations.Under the Surface Mining Control and Reclama-tion Act, section 515—the bureau is using modelsto predict the effect of coal mining on hydrologicregimes in Coshocton, Ohio.Under the Resource Conservation Act, section 6—the bureau uses models to predict the effects of coalmining on the hydrologic system, particularlyground water, in the Power River Basin in Wyo-ming. This information is also made available tomine operators to assist them in preparing EISS,and in complying with regulatory standards set bydifferent agencies. This work is also related to theSurface Mining Control and Reclamation Act.

One Bureau of Mines model, UNSAT2, is used topredict seepage patterns and quantities from mine-wasteimpoundments. Applications of this model include anal-yses of the stability of spent oil shale deposits and theflow of leachates into ground water systems.

Office of Surface Mining

The Office of Surface Mining administers portionsof the Surface Mining Control and Reclamation Act,using models in connection with several of its programsunder title V of the act—Control of the EnvironmentalImpacts of Surface Coal Mining.

Section 515 authorizes environmental protection per-formance standards for surface coal mine reclamation.The office and its contractors use models in assessingthe cumulative effect of surface coal mining on an area’s

hydrologic regime to determine regulations and stand-ards for protecting water quality and quantity. Thisinformation is provided to State and local agencies andto private sector interests. Under section 510 of the act,the office uses models to evaluate permit applicants’assessments of the hydrological consequences of theirproposed mining activities, and as a basis for approv-ing or denying permits. The office aiso uses models toevaluate protection of the hydrologic balance under theenvironmental protection standards set pursuant to sec-tion 515 of the Surface Mining Control Act.

Office of Water Research andTechnology (OWRT)

The principal functions of OWRT are to improvetechnologies and methods for addressing water resourceproblems, train water scientists and engineers, coordi-nate water research, and disseminate water resource in-formation. These tasks, carried out under the State In-stitute Program by university water resources researchinstitutes in each State, are aimed at resolving local,State, and regional water and water-related problems.The State water resources research institutes and theState Institute Program are described in detail in chapter4 of this report.

Because OWRT is not a mission-oriented agency, itdoes not itself use water resource models. It is activein funding model development, however. Water re-source models developed by OWRT grantees and con-tractors span almost the entire range of issue areas andmodel uses. At present, OWRT is assessing the needto develop simpler, less data-intensive models than thosethat now exist. A concomitant concern is to adapt exist-ing models to specific applications.

Fish and Wildlife Service

The primary responsibilities of the Fish and WildlifeService consist of conserving and protecting fish andwildlife resources and ensuring their equal considera-tion with other aspects of water development planning

as required by the Fish and Wildlife Coordination Act(16 U.S.C. 661). The service has a vital interest in waterand related land-use programs, including diversions,impoundments, facilities development, and streamflowregulation. The service participates actively in studiesleading to the formation of national, regional, or riverbasin plans for using water and related land resources.

The service uses models in several of its programsconcerned with managing water resources for the benefitof fish and wildlife. When asked to analyze construc-tion projects and alternatives proposed by other agen-cies in EISS, the service uses models to project the rel-ative impacts of the proposed construction and its alter-


natives over a number of years. Models also help deter-mine the potential effects of a project on endangeredand threatened species, as well as on water flow require-ments for these species. The service also uses modelsin surveys and investigations of the fish and wildlife im-pacts of water resource projects under the Federal Recla-mation Act (43 U. S.C. 421 and 422), dealing with irri-gation distribution systems and construction of smallwater resource projects, respectively.

The Fish and Wildlife Service uses models for severalpurposes in its programs in accordance with the Fishand Wildlife Coordination Act. Under this legislationthe service recommends modifications in project designand operation consistent with sound wildlife manage-ment principles.

Some of these uses are:●

●

For water resources planning: the service usesmodels to help assess water availability and in-stream flows, to predict the effects on habitats sur-rounding such projects, and to assess the impactsof water development projects.For operation and management activities: the serv-ice uses models to help determine waterflow re-gimes and how to mitigate impacts from construc-tion projects.

The service also acts in an advisory capacity to Stateand local agencies that use models to assess instreamflow needs and the effects of construction and energy-related activities on aquatic populations.

For evaluating the effects of powerplant design andsiting, the Fish and Wildlife Service principally uses twotypes of models. One type includes fairly large simula-tion models for investigating and predicting physical im-pacts of powerplant operation (specifically, cooling) onthe aquatic environment. Such impacts include fishentrainment-impingement, as well as habitat modifica-tion. The service also uses a Multiple-Objective Pro-graming (MOP) model to study regional alternativesfor powerplant location. The regional energy locationmodel (RELM) was recently modified to incorporatebiological/ecological considerations into an economic op-timization model. This modified model is intended toinclude ecological criteria in siting decisions at theearliest possible planning stage, thus reducing the like-lihood of expensive litigation over the development offuture energy resources.

Bureau of Reclamation

The Bureau of Reclamation is involved in develop-ing water and related land resources in the 17 WesternStates. Planning such development is a multiobjectiveand multipurpose activity directed at irrigation, munic-ipal and industrial water supply, hydroelectric power,

flood control, navigation preservation, propagation offish and wildlife, outdoor recreation, drainage, pollu-tion abatement, water quality control, streamflow aug-mentation, watershed protection, and erosion control.All the bureau’s water and land resource developmentactivities are authorized under the Federal ReclamationAct (43 U.S.C. 421).

During the last 15 years, considerable attention hasbeen directed toward developing and managing Westernresources. As a result of this attention, a large body ofwater-related legislation has been passed that relates to,and has some impact on, the basic water and land re-sources development mission of the bureau. Sections208, 209, and 303 of the Clean Water Act require thebureau to consider areawide wastewater treatment facil-ities and management, river basin planning and man-agement, and quality standards and implementation inplans, respectively. The National Environmental PolicyAct of 1969 in section 102 requires evaluation of im-pacts from water resource development projects bothduring construction and for the long term.

The Colorado River Salinity Control Act was estab-lished to define and implement effective salinity controlmeasures to meet established water quality standards.Other legislative acts affecting the bureau’s water re-source development activities include: the EndangeredSpecies Conservation Act; Executive Order No. 11988,sections 2 and 3 (flood plain management); the WaterResources Development Act, section 73, (nonstructuralmeasures); and the Flood Control Act (building floodcontrol structures).

To assist in accomplishing its basic water and landresource planning, development, and management mis-sion, the Bureau of Reclamation has developed severalwater resource-related models. These models are usedin the planning, design, and operational phases of theagency’s mission, and are employed extensively to eval-uate the effects of planned actions as they relate to andaffect the legislation described previously. These modelswere not developed for any specific legislation or as aresult of it, but are used as tools to assess the impactsof planned actions or change in operating strategies tosee how they relate to and comply with the various stat-utes.

The bureau uses physical/ecological ground and sur-face water models, as well as various economic/socialmodels. All of the bureau regional offices and manyof its project offices use surface water models. Thesemodels are usually developed or adapted by the officeusing them. Most of these models are project-specific,and simulate project operations over various time peri-ods and with various hydrological inputs. The modelsare used for single projects, multiple projects, or entireriver basins. Model applications include developing res-ervoir operation strategies; hydropower simulation; and


water quality, water rights, water availability, and floodcontrol studies.

The bureau uses models to help determine how tem-perature changes or peaking power releases resultingfrom various reservoir operation, release, and withdraw-al schemes would affect downstream fisheries and recrea-tion and power users. This information is communicatedto States, localities, and other Federal agencies so thatreservoir operations can comply with State and Federalfish habitat temperature guidelines, optimize power gen-eration, and meet water user contract agreements.Models are also used to evaluate the impact of reser-voir and stream operations on fish habitat and popula-tions.

The bureau makes extensive use of simulation modelsto evaluate the impacts and effectiveness of irrigationsystems. The models provide information for determin-ing whether projects should be modified to exclude landsthat irrigation would affect adversely. They are also usedto help predict the quality and quantity of irrigationreturn flows and the effects of project development onaquifer quality, receiving stream quality, and chemical,physical, and biologic properties of project soils. TheReturn Flow Quality Simulation model has been usedto calculate salinity and other ground and surface waterquality changes from major irrigation projects in Cali-fornia, Colorado, and the Dakotas. This model can alsobe used to schedule the timing and amounts of waterrequired for a variety of crops and climates.

Models are used in developing salinity level stand-ards and in evaluating the effects of specific actions onsalinity levels in the Colorado River Basin. Specifical-ly, the models estimate the effect of future water useson salinity and the cost effectiveness of salinity controlmeasures for meeting established standards. The modelsalso help determine the technical feasibility of proposedsalinity control measures at point, nonpoint, and agri-cultural sources. In addition, the models are used todevelop operating strategies for reservoirs, determinethe optimum size of desalting plants and reservoirs, andmaximize the water supply for all competing uses, in-cluding power, municipal and industrial, irrigation, in-stream flows for fisheries and recreation, and water qual-ity.

Other types of surface water models used by the bu-reau include unsteady flow routing models to predictoutflows and downstream routings of floods from hypo-thetically breached dams. These models assist in devel-oping maps of expected inundation areas for emergencypreparedness planning. The bureau also employs andcontinues to develop synthetic models to describe ex-treme storm precipitation and meteorologic conditions.These are used to determine maximum probable floodvalues for sizing spillways and to describe atmosphericmodification potential for precipitation augmentation.

The bureau also uses a wide variety of ground watermodels in water resource planning, system design, andproject operation. With few exceptions, these are theo-retically based models that simulate the movement ofboth water and solutes.

A major recent effort by the Bureau has been to devel-op and implement the Bureau of Reclamation EconomicAssessment Model (BREAM), a simulation-type model.BREAM’s basic function is to provide a systematic,theoretically sound approach to projecting population,employment, and income. The bureau envisions using

BREAM principally for alternative futures analyses,public involvement, projection of municipal and indus-trial water requirements, and economic/demographicimpact assessments related to water resource construc-tion activities and long-run uses and outputs of waterresource development. The economic and demographicoutputs of BREAM are also major inputs and drivingvariables necessary for evaluating the social impacts ofwater resource development activities. The bureau usesother economic models to analyze and optimize farmenterprises in determining irrigation benefits and pay-ment capacity, and to analyze hydropower additions toexisting power system networks.

The bureau has also developed data management andscheduling systems based on models of managementfunctions. These provide for scheduling program activ-ities, and funding and manpower requirements.

U.S. Geological Survey (USGS)

USGS conducts research on the physical features ofthe Nation, including its mineral and water resources.This research is based on the fields of hydroloW, geol-ogy, geochemistry, and geophysics, and aims at develop-ing new technologies and methods for appraising andconservin g minerals and water. The Water ResourcesDivision of USGS is responsible for investigating andappraising the source, quantity, quality, distribution,movement, and availability of both ground and surfacewater. The legal authority for this work stems from theact of October 2, 1881 (25 Stat. 505, 526), augmenting

the organic act establishing USGS in 1879, and has beenreinforced by the general language of annual appropria-tion acts for the Department of the Interior since 1894.AIso, USGS has been the indirect recipient of programresponsibilities under many different water resource lawsthat are primarily directed toward resource managementagencies.

USGS uses models in connection with many of itsprograms. Models are used to study flow, ion transport,and geochemistry in aquifer systems; information thusgenerated is made available to Federal and State agen-cies, and to the general public. Modeling activities ofthe USGS Water Resources Division—in particular, the


Federal-State Cooperative Program—are described indetail in chapter 4 of this report. Models are used inconnection with USGS activities relating to sections ofthe Clean Water Act, namely:

● section 201 —grants for construction of treatmentplants;

. section 3 I l—oil and hazardous substances liability;

. section 3 14—clean lakes;

. section 3 16—thermal discharges and exemptions;and

. section 404—guidelines and permits for use ofdredge or fill materials.

USGS also develops models for use by itself andothers in programs under the Resource Conservationand Recovery Act (Public Law 94-580).

USGS develops models to study many aspects of qual-ity in selected rivers of the United States. These modelsanalyze flow and transport, dissolved oxygen, and ther-mal discharges. Use of these models is generally relatedto provisions of the Water Resources Planning Act,which requires a continuing study of the adequacy ofthe Nation’s water supply. USGS is also developingmodels that will be used to assess the impact of surfacecoal mining on the hydrology of mined river basins, anactivity relating to section 515 environmental protec-tion standards under the Surface Mining Control andReclamation Act.

USGS is also concerned with flood control and usesmodels in connection with its activities under the FloodControl Act and sections 2 and 3 of Executive OrderNo. 11988, dealing with flood plain management.USGS models determine flood discharges for specifiedrecurrence intervals, flood profiles, and flood routings.The information the models produce is available to ap-propriate Federal, State, and local authorities and tothe public.

In addition to these uses of models, USGS indicatedthat it uses or is developing models in connection withits activities under the following acts:

● The Safe Drinking Water Act (Public Law 93-523):— section 1421—protection of underground

sources of drinking water; and— section 1444—special study and demonstration

project grants for wastewater reuse, reclama-tion, and recycling processes.

The Surface Mining Control and Reclamation Act:— section 506—surface mining permits; and— section 5 15—environmental protection stand-

ards for reclamation.● The Resource Conservation Act:

— section 5—data collection about soil, water, andrelated resources;

— section 6—soil and water conservation pro-grams.

● The Water Resources Development Act of 1974:— section 73—nonstructural measures.

● The Federal Reclamation Act:— 43 U.S.C. 421—irrigation distribution systems.

USGS has made significant contributions to the devel-opment of models for analyzing ground water problems.Specific areas include: physical characteristics of groundwater flow, effects of ground water depletion on surfacelands, flow in coupled ground water/stream systems, in-tegration of rainfall-runoff basin models with soil mois-ture accounting and aquifer-flow models, interaction ofeconomic and hydrologic considerations, prediction ofpollutant transport in aquifers, and estimation of theeffects of development schemes for geothermal systems.USGS is actively involved in updating and improvingmost of these models.

USGS surface-water modeling efforts include: flowrouting in streams, estuaries, lakes, and reservoirs; sedi-mentation; transport of physical, chemical, and bio-logical constituents; coupled stream-aquifer flow sys-tems; physical hydrology for rainfall-runoff relations,stream simulations, channel geometry, and water qual-ity; statistical hydrology for synthetic streamflows,floods, reservoir storage, and water quality; manage-ment and operations problems; and water quality prob-lems that result from environmental pollution, such asthermal loading, pesticide pollution, and freshwatereutrophication.

Independent Agencies

Council on Environmental Quality (CEQ)

CEQ has responsibilities for national overviews ofenvironmental quality conditions and trends. To satisfythese responsibilities, CEQ with the cosponsorship ofother agencies and organizations, has developed theUPGRADE computerized environmental analysis sys-tem. This system of models and data bases is used toanalyze water quality, air quality, environmental health,and socioeconomic data. The system permits cross-anal-ysis (e. g., water pollution vs. health) at the county level.It is an interactive system and is completely English-language prompted. Data bases on wide-ranging sub-ject areas are being added to the system in order tobroaden and deepen the system’s analytical capabilities.

Environmental Protection Agency (EPA)

The responsibilities of EPA include establishing andenforcing environmental standards, conducting researchon the impacts of pollution and ways to control it, andassisting CEQ in developing and recommending to thePresident new policies for protecting the environment.


With respect to water resources, EPA is concerned withproviding water supplies that are adequate in qualityfor all beneficial purposes. The following EPA officesindicated use of water resource models in connectionwith program responsibilities.

1. Office of Research and Development (ORD)—ORD is actively involved in developing and using waterresource mathematical models and predictive tech-niques. The major thrust of its modeling activity is todevelop capabilities to translate water quality standardsinto maximum allowable pollution loadings, select themost cost-effective combination of controls, and assessenvironmental risks associated with production, trans-port, use, and disposal of toxic chemicals. ORD has con-ducted special studies of the Great Lakes, ChesapeakeBay, James River, and other areas where other EPAoffices have requested technical assistance.

Two principal types of models have been developedas part of the ORD Great Lakes program. The first,a series of physical/ecological models, focus on the re-lationship of phytoplankton biomass to nutrient load-ings. These models were developed to understand andcontrol accelerated eutrophication in portions of theGreat Lakes; they are being used to recommend guide-lines for nutrient discharges. The second type of modeldescribes the transport and fate of toxic pollutants in-troduced into the Great Lakes, in order to determinethe levels of control required to keep environmental riskswithin acceptable levels.

ORD has also developed nonpoint source, toxic pol-lutant, eutrophication, and circulation models for theChesapeake Bay. These address the problems of acceler-ated eutrophication in portions of the bay, the declineof submerged aquatic vegetation, and associated impactson aquatic life and commerce.

ORD assists EPA’s operational programs in selectingand using models to deal with specific problems. Thesemodels include urban and rural runoff models and re-ceiving-water quality models. The models are used indetermining control requirements to be placed on dis-charges and in planning studies required under section208 of the Clean Water Act. ORD also provides techni-cal assistance with the Exposure Analysis Modeling Sys-tem (EXAMS), a major mathematical model for assess-ing the primary pathways, persistence, and fate of toxicorganic chemicals in freshwater systems.

Future water resource modeling needs ORD is ad-dressing concentrate on providing the capability to assessenvironmental risks associated with toxic chemicals inground and surface water, and identifying cost-effectivepollution control measures to attain and maintain waterquality goals.

2. Office of Water Regulations and Standards(OWRS)—EPA’S OWRS uses some models in devel-

oping guidelines for toxic and pretreatment effluentstandards pursuant to section 307 of the Clean WaterAct. The models OWRS currently uses address threemain problem areas: the fate of pollutants dischargedinto receiving waters, and their effect on water quality;the quantity and quality of runoff from urban and agri-cultural areas, and its impact on receiving waters; andthe economic effects of water pollution regulations onindustries.

A principal model in the first category is EXAMS.The Water Quality Analysis Branch of OWRS currentlyuses EXAMS to evaluate different control strategies forselected pollutants in order to determine whether thesepollutants should be subject to best available technology(BAT) requirements or to more stringent controls. TheEXAMS model is being used in conjunction with agri-cultural runoff models, such as ARM-II, and receiv-ing-water quality models, such as QUAL-H, for screen-ing analyses of new pesticides.

Another major use of models of this type is in estab-lishing and enforcing wasteload allocations for NationalPollutant Discharge Elimination System (NPDES) per-mits. These models are used to assess the assimilativecapacity of a water body and to relate stream water qual-ity levels to pollutant discharges. The models are alsoused to determine whether dischargers are complyingwith permit allocations.

OWRS’S Office of Analysis and Evaluation assessesthe economic impact of water pollution regulation onindustrial sectors by one of two techniques, dependingon industry size. For small industries, the office performsindustry-specific financial analyses to determine if com-pliance with point-source BAT regulations will forcefirms to close. The office uses econometric models tostudy larger industries. These models deal with capitalrequirements, pricing, future demand for products, andthe effects of regulation on industry growth.

3. Office of Water Program Operations (OWPO)—Urban and agricultural runoff models are used to a lim-ited degree by the national office of the Water PlanningDivision of OWPO in planning studies. These modelsare used at the State level to estimate potential runoffand to evaluate different pollution control strategies, asrequired under section 208 of the Clean Water Act.

4. OffIce of Water and Waste Management—EPA’sDrinking Water Program in the Office of Water andWaste Management has the responsibility to implementprovisions of the Safe Drinking Water Act, and it usessome models to improve the decisionmaking process.Under section 1412, for example, it uses health effectsmodels as part of the background information base for

setting standards and promulgating regulations. Thesemodels provide data on the health risk from exposureto contaminants in drinking water. Information from


such models has been used in the standard-setting proc-ess for radioactive and organic contaminants. The pro-gram also uses economic and benefit/cost models todetermine the economic effects of alternative policy andregulatory options on the water supply industry.

Protection of underground sources of drinking water,prescribed in section 1421 of the Safe Drinking WaterAct, is also a responsibility of the Drinking Water Pro-gram. Hazardous and toxic wastes have frequently beendisposed of through injection into underground forma-tions. The program uses models to provide informationon the impact of injection practices on the natural sys-tem, the costs of constructing new wells, and the eco-nomic costs of shutting down existing wells. By compar-ing regulatory and remedial alternatives available, pro-grams can be developed to balance the risks and costsof contamination prevention measures.

The Drinking Water Program has also conducted amajor surface impoundment assessment authorized bysection 1442 of the act. The assessment includes a na-tionwide survey of surface impoundments in order todetermine their potential for contaminating groundwater. Uniform criteria were developed and used toassess current and potential leakage of contaminants intoground water. These criteria include, among others,type of geology underlying the site, type of waste in-volved, proximity of aquifers, and capability of soil toattenuate pollutants. Based on data collected, groundwater models can be developed to account for these fac-tors in predicting an impoundment’s potential for con-taminating ground water.

The Drinking Water Program also uses models toevaluate State needs and capabilities in order to deter-mine the appropriate grant amounts States receiveunder section 1443 of the Safe Drinking Water Act.These are financial models, but they take into considera-tion such factors as the number and type of injectionwells in the State, the number of wells used as part ofa water supply system, the geographic area, and themanpower available in the State.

Models have also been used to develop a more com-plete understanding of sole-source aquifers. Theseground water resources may, in some parts of the coun-try, provide the only available source of water. Modelsprovide information on the impact of discharges andother economic activities on these sources of drinkingwater. Facilities that may adversely affect these aquifersinclude: leaking underground gasoline storage tanks,waste disposal sites, improper land use, construction ofroads and buildings in the recharge zone, and pollutionof adjacent streams. Once the relative impacts of sourcesof contamination are determined and evaluated, EPAworks with State agencies and communities to establishand enforce procedures to prevent future aquifer con-tamination.

5. Office of Toxic Substances (OTS)—EPA’S OTSuses models in several of the programs it carries outunder current water resource legislation. The principalfocus of its model use is the transport and fate of toxicchemicals released into the aquatic environment. Cur-rently, models are being used in OTS for risk assess-ment studies, to estimate the movement of pollutantsthrough the environment and their expected environ-mental concentrations. The office uses models in con-nection with activities under the Toxic Substances Con-trol Act. Its models help measure the effectiveness ofregulatory options in order to set standards accordingto sections 4, 5, and 6 of the act, which deal with test-ing, issuing manufacturing and processing notices, andregulating hazardous chemical substances and mixtures.

OTS uses a three-step analysis to determine whethera substance should be regulated, and, if so, how strin-gent the regulation should be—such regulation couldrange from labeling a substance as hazardous to ban-ning its use entirely. The office first determines the ex-posure of human and nonhuman populations to the toxicsubstance. It then combines this exposure informationwith estimates of health and ecological effects for variousexposures. Finally, the office weighs these costs againstthe benefits of using the substance. Models are used inaccomplishing the first step of the analysis.

In addition to this use of models, OTS uses modelsto help design chemical testing programs and to developmonitoring studies carried out under provisions of theToxic Substances Control Act.

OTS is also involved in programs under the FederalInsecticide, Fungicide, and Rodenticide Act of 1972(Public Law 92-516), and uses models in conductingthese programs. In its review of pesticide product regis-trations, OTS must consider the potential effect of thesubstance on ground and surface waters. In this con-nection, OTS uses models to assess pesticide runoffpotential and the likelihood of ground water contamina-tion by pesticides, and to predict pesticide concentra-tion in streams. OTS also uses models for advising Stateand local agencies of the likelihood of ground water con-tamination by pesticides.

OTS mainly uses the EXAMS model, although itsEvaluation Division makes limited use of ARM-II inpesticide screening studies. OTS is developing multi-media (water, air, land) models for preliminary assess-ments of a chemical’s behavior in the environment.These models provide concentration estimates used inthe exposure calculations that support risk analysis. Themultimedia formulations are capable of accommodatingvarious types of chemicals and modes of release into theenvironment. In addition, two ground water contamina-tion models are being developed for OTS.

6. Office of Water Enforcement—EPA’s Office ofWater Enforcement uses models in connection with its


activities under the NPDES permit program and sec-tions 301 and 316 of the Clean Water Act. The NPDESprogram under section 402 of the Clean Water Act re-quires issuance of permits to regulate discharge of pol-lutants into the Nation’s waters. Permit limits are eithertechnology or water quality based. When technol-ogy-based limits are unavailable or inadequate to meetwater quality standards, permits are based on ‘‘best pro-fessional judgment, ’ which may include the use ofwasteload allocation or other water quality models. Inaddition, water quality models, dispersion models, andhydrological models are used to measure compliancewith water quality standards.

Under section 316 of the Clean Water Act, whichauthorizes variances from thermal discharge standards,the office uses predictive studies of entrainment and im-pingement losses to populations of fish and shellfish inenforcing regulations governing powerplant siting. Italso uses fish population models and hydrological modelsfor the cooling intake structures program.

Section 301, which includes environmental and eco-nomic variances, demands the use of models when pre-dictive demonstrations are needed to establish ambientconcentrations of nonconventional pollutants.

National Science Foundation (NSF)

NSF does not use water resource models, nor doesit directly fund the development of specific models. Itdoes, however, fund basic research at universities thatmay contribute to the formulation of water resourcemodels. Such research may also produce componentsand mathematical techniques that can be used in de-veloping such models or in checking their scientificvalidity.

The research NSF funds in the area of water resourcesis for the purpose of building a firm scientific founda-tion, wherever possible, for empirical procedures andpractices that are used in developing water resourcemodels. Well-known examples are rainfall-runoff rela-tionships and rainfall-soil erosion relationships.

NSF responds only to unsolicited basic research pro-posals in water resource engineering. During fiscal year1979, NSF supported hydrologic and water resourcestudies on hydrologic data, irrigation, planning, floodforecasting, reservoir control, and surface runoff, amongothers. Any or all of these topics may have models as-sociated with the project.

Water Resources Council (WRC)

WRC encourages Federal, State, and local govern-ments and private enterprise to conserve, develop, anduse water and related land resources on a comprehen-sive and coordinated basis. WRC also conducts periodic

national water assessments to identify the Nation’s criti-cal water problems.

For its Second National Assessment in 1978, WRCdeveloped a water supply adequacy model. This modelis based on the concept of a balance between water useand water supply for both ground and surface water.The model is comprised of 21 water resource regionsand 106 subregions. The subregions have data on waterinflow or supply from upstream subregions, interbasinimports, precipitation runoff, and ground water. Wateruses include interbasin exports, consumption, andevaporation. Ground water recharge is accounted forin the model and is not considered a loss. The hydrologicand water-use data fed into this model were derivedthrough models incorporating precipitation records,runoff estimates, economic growth projections, andother measured or calculated variables at the water-accounting-unit level (352 nationwide). These modelswere produced or operated for WRC by various Federal,State, and regional agencies.

The water supply adequacy model helped identifyseveral water supply problems. These included shortagesresulting from poor distribution of supplies, instream -offstream conflicts, competition among various off-stream users, ground water overdraft, quality degrada-tion of ground and surface water, and institutional con-flicts that prevent a unified approach to water manage-ment.

WRC’S Water and Energy Program was authorizedby the Federal Nonnuclear Energy Research and Devel-opment Act of 1974 (sec. 13 of Public Law 93-577),which directs WRC to conduct regional and site-specificwater resource assessments of potential energy develop-ments. For this purpose, a number of computerizedmodels have been used by various WRC contractors andother Federal and State agencies, e.g. , the ColoradoRiver System Simulation (CRSS) of the Bureau ofReclamation and the respective models of the WhiteRiver developed separately by Utah and Colorado.These, and similar models, evaluate flow regime, hydro-power impacts, salinity and suspended solids concen-trations, and other water quantity and quality changesanticipated from energy developments.

WRC presently evaluates river basin plans pursuantto section 209 of the Clean Water Act. It is testing amodel that assesses water quality impacts of existing orproposed river basin management schemes—specific-ally, in its Yadkin-Pee Dee Level-B study.

Some river basin commissions under the purview ofWRC use models to help plan or evaluate projects devel-oped under section 102 of the Water Resources Plan-ning Act. This section deals with regional or river basinplans and programs and their relationship to other con-siderations. The commissions use models to analyze theimpacts of potential projects on water supply, to esti-mate depleted flows at key gaging stations, and to com-

186 . Use of Mode/s for water Resources Management, Planning, and Policy

pare the cost effectiveness of alternative wasteload reduc-tion strategies.

Federal Emergency Management Agency

The Federal Emergency Management Agency,through the Federal Insurance Administration (FIA),administers the National Flood Insurance Program asestablished by the National Flood Insurance Act of 1968(Public Law 90-488). The program provides flood insur-ance availability to property owners within communitiesthat adopt and enforce minimum flood plain manage-ment measures to mitigate future flood losses. The actalso requires the identification of flood-prone areas andrisk zones within such areas.

Flood insurance studies are conducted for individualcommunities to establish flood plains, floodways, regu-latory flood elevations, and insurance risk zones. Thesedata are often developed using models and are subse-quently provided to participating communities as thebasis for their flood plain management program. Theyare also used to establish actuarial flood insurance rates.

Several different hydrologic models have been usedby FIA to establish flood flow frequencies and for floodhydrography routing. The most commonly used hydro-logic models are the HEC-1 Flood Hydrography Pack-age, developed by the Corps of Engineers, and theTR-20 Computer Program for Project Formulation, de-veloped by SCS. These models simulate the rainfall-runoff process on watersheds and flood hydrography pro-gression in downstream channels.

Several hydraulic models have been used to establishflood elevations and floodways in streams. The mostcommonly used hydraulic models are the HEC-2 WaterSurface Profile Package, developed by the Corps of En-gineers, WSP-2 (TR61) and FLDWY (TR-64), devel-oped by SCS, and E431, developed by USGS. Thesemodels simulate open channel steady uniform flow usingthe standard step backwater method.

FIA has also developed two coastal storm surge mod-els, including one for northeasters and one for hurri-canes. These models utilize joint probability techniquesand coastal hydrodynamic principles to establish regula-tory flood elevations on the Atlantic and Gulf coasts ofthe United States. A finite element model has also beenestablished to simulate storm surges in the ChesapeakeBay.

Nuclear Regulatory Commission (NRC)

NRC water resource activities are related to deter-mining hydrologic factors in nuclear facility site evalua-tions, ecological effects of water use, and radionuclide

transport in ground and surface waters. NRC has usedmodels in connection with all of these programs. Forexample, to comply with regulations under section 102of the National Environmental Protection Act, NRCused models to evaluate powerplant intake effects onHudson River striped bass.

NRC has specific responsibilities under the UraniumMill Tailings Radiation Control Act and the Atomic En-ergy Act. Under the first act, NRC uses models to deter-mine the movement and concentration of ground waterpollutants from uranium mill tailings. Information pro-vided by these models was used to prepare a generic en-vironmental impact statement on uranium milling andassociated rule changes. NRC also uses models to sup-port various licensing actions. Models help supportlicensing decisions for uranium mills, tailings disposalsystems, and uranium extraction operations. Modelsalso help measure compliance with regulations and li-cense conditions.

Under the Atomic Energy Act, NRC uses models tohelp it evaluate proposed sites for nuclear powerplants,fuel cycle facilities, and waste disposal sites. Models areused to help determine whether a plant’s water supplyis adequate for safety-related functions, as specified inregulations. NRC also uses models to evaluate whetherproposed nuclear facilities are in compliance with regula-tions governing flood protection.

Models have been used by NRC in carrying out itsresponsibilities under the Atomic Energy Act to limitradioactive liquid effluents to ground and surface waters.NRC is using models to help prepare an EIS and to for-mulate proposed regulations governing the disposal oflow-level radioactive waste and low-activity bulk solidwaste. The models are presently being used to evaluatesiting criteria and alternative disposal techniques interms of radionuclide transport and concentrations atsite boundaries. When disposal site regulations areadopted, site-specific models will be used to determinewhether adequate protection exists to prevent radio-nuclide migration from exceeding acceptable limits.Models are also used to help determine whether othertypes of nuclear facilities are in compliance. These mod-els help evaluate potential concentrations of radionu-clides in ground and surface waters as a result of bothaccidental and normal releases.

NRC provides assistance to States in the use of modelsto evaluate radionuclide migration from disposal sites.This is done as part of the agreement State program,through which certain States, pursuant to section 274of the Atomic Energy Act, have entered into an agree-ment with NRC for assuming regulatory control of by-product, source, and small quantities of special nuclearmaterials.


ATTACHMENT I.—REFERENCES BY AGENCY

Department of Agriculture

Economics and Statistics Service

1. Dyke, P., and Hagen, L., Resource Systems Pro-gram, Natural Resource Economics Division, ECO-

nomics, Statistics, and Cooperative Service,USDA, Land and Water Resource and EconomicModeling System, LA WREMS Directoxy, version1, January 1979.

2. Land and Water Conservation Task Force,‘‘LAWREMS, Land and Water Resources andEconomic Modeling System, Current Capabilities,Conceptual System, Future Options, Final Draft, ”USDA, December 1978.

3. Weisz, R. N., National Systems Section, NaturalResource Economics Division, Economic, Statis-tics and Cooperative Service, USDA, October1979.

Forest Service

4. Forest Service, USDA (unknown title), sec. 2, Hy-drologic and Soils Simulation Programs, pp.32-65.

5. Group Leader, Watershed Systems DevelopmentGroup, Forest Service, USDA, Userguide Ab-stracts.

Science and Education Administration

6. Data Systems Application Division of AgriculturalResearch Service, USDA, File of A.gricultural Re-search Models (FARM), November 1977.

7. Knisel, W. G., “A Field Scale Model for Esti-mating Chemicals, Runoff, and Erosion FromAgricultural Management Systems, Science andEducation Administration, USDA.

8. Wischmeier, W. H., and Smith, D. D., “Predict-ing Rainfall Erosion Losses—A Guide to Conser-vation Planning, Science and Education Ad-ministration, USDA, agriculture handbook No.537, 1978.

Soil Conservation Service

9. Ecology Simulations, Inc. , Athens, Ga. ,“SECWATS: A Simulation Concept and Modelfor Assessment, Evaluation and Optimization ofSoutheastern Coastal Plain Stream ModificationProjects, With Application to Horse RangeSwamp, South Carolina. ” contract No. AG

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23

24,

SCS-001 11, submitted to: SCS, USDA, June 1,1978.King, Arnold D., ‘‘Universal Soil Loss Equation,Soil Conservation Service, 1979.Pasley, R. M., Dempster, T., Stierna, J., Cald-well, B., King, A., and Evans, G., interviews withSoil Conservation Service and USDA personnel,Aug. 30, 1979.Soil Conservation Service, “Executive Summaryof Responses to Objectives, USDA, Oct. 19,1979.Soil Conservation Service, Farmer Decision andConservation Simulation Model, draft RLC: PEB,USDA, Aug. 23,1979.Soil Conservation Service and Stanford ResearchInstitute, draft, “Documentation of the SRI Meth-odology for RCA Evaluation, September 1979.Soil Conservation Service, West Technical ServiceCenter, User’s Guide to the Irrigation MethodAnalysis Program, IRMA, Colorado River BasinSalinity Control Studies and Irrigation Planning,USDA, February 1978.Metcalf and Eddy, Inc. (sponsored in part byUSDA), Process Design Manual for Land Treat-ment of Municipal Wastewater, October 1977.Soil Conservation Service, USDA, “LandDamage Analysis, ” attachment, 1976.Soil Conservation Service, Engineering Division,WSP-2 Computer Program, technical release No.61, USDA, May 1976.Soil Conservation Service, Special Projects Divi-sion, User Guide to the SCS Automated Irriga-tion Water Use Requirements Model Utilized inthe 1975 National Water Assessment Program,USDA, May 1975.Soil Conservation Service, Engineering Division,Urban HydroZogy for Small Watersheds, technicalrelease No. 55, USDA, January 1975.Soil Conservation Service, ‘ ‘Urban FloodwaterDamage, Economic Evaluation, attachment 28,USDA, 1976.Soil Conservation Service, Engineering Division,Computer Program for Project Formulation,Structure Site AnaZysis, technical release No. 48,USDA, February 1971.Soil Conservation Service, Economics Division,ECON2, Economics—Floodwater Damages, pro-gram description, Apr. 1, 1969.Soil Conservation Service, Engineering Division,Computer Program for Project Formulation, Hy-drology, technical release No. 20, 1965.

188 ● Use of Mode/s for water Resources Management, Planning, and Policy

25. Soil Conservation Service, Applied ConservationEffects System, briefing paper, USDA.

Department of Commerce

NOAA: National Weather Service

26.

27.

28.

29.

30.

31.

32.

33.

34.

Curtis, D. C., and Schaake, Jr., J. C., “The NWSExtended Streamflow Prediction Technique, ” pre-sented at the Engineering Foundation Conference:Water Conservation-Needs and ImplementationStrategies, held at Franklin Pierce College,Rindge, N. H., July 9-13, 1978.Fread, D. L., ‘ ‘National Weather Service Opera-tional Dynamic Wave Model, presented at Nu-merical Modeling for Engineers Symposium,Vicksburg, Miss., U.S. Army Corps of Engineers,Waterways Experiment Station, Apr. 17-21, 1978.Fread, D. L., ‘ ‘The NWS Dam-Break Flood Fore-casting Model, presented at Dam-Break Model-ing Seminars at Kansas City, Mo., Sept. 18-22,1978.Hydrologic Research Laboratory, NationalWeather Service River Forecast System ForecastProcedures, NOAA technical memorandumNWS-HYDRO-14, Silver Sring, Md., Depart-ment of Commerce, 1972.Krsysztofowicz, R., Davis, D. R., Ferrell, W. R.,Hosne-Sanaye, S., Perry, S. E., and Robotham,H. R., “Evaluation of Flood Forecasting ResponseSystems II, report to Hydrology Laboratory, Of-fice of Hydrology, National Weather Service,NOAA, Department of Commerce, contract No.6-35229, Reports on Natural Resource SystemsNo. 33, University of Arizona, Tucson, Ariz.,1979.Office of Hydrology, National Weather Service,“Response to OTA Questionnaire: Task Force onWater Resource Modeling in Federal Agencies,personal correspondence, October 1979.Ostrowski, J. T., National Weather Service,“Products Useful for Reservoir Regulation, ”Hydrologic Research Laboratory, NationalWeather Service, NOAA, Silver Spring, Md.,mimeograph, 1979.Peck, E., and Hudlow, M., staff, Ofilce of Hydrol-ogy, National Weather Service, NOAA, Depart-ment of Commerce, personal interview, Aug. 29,1979.Schaake, Jr., J. C., “Use of Mathematical Modelsfor Hydrologic Forecasting in the NationalWeather Service, ‘‘ in Proceedings of the EPA Con-ference on Environmental Modeling and Simula-tion, W. R. Ott (cd.), report No. EPA-600 /9-76-

35

106 (Cincinnati, Ohio: Environmental ProtectionAgency, 1976).Twedt, T. M., Schaake, Jr., J. C., and Peck,E. L., “National Weather Service ExtendedStreamflow Prediction, ” in Proceedings of theWestern Show Conference, Albuquerque, N. M.,Apr. 19-31, 1977.

Department of Defense

U.S. Army Corps of Engineers

36. Boyd, M. B., ‘‘Response to OTA Questionnaire:Task Force on Water Resource Modeling in Fed-eral Agencies, personal correspondence, October1979.

37. Eichert, B. S., and Bonner, V. R., HEC Con-

38

39,

40,

41,

42,

43,

44,

tribution to Reservoir System Operation, technicalpaper No. 63 (Davis, Calif.: Hydrologic Engineer-ing Center, U.S. Army Corps of Engineers,August 1979).Gundlach, D. L. and Thomas, W. A., “Guide-lines for Calculating and Routing a Dam-BreakFlood, ‘‘ research note No. 5 (Davis, Calif.:Hydrologic Engineering Center, U.S. Army Corpsof Engineers, May 1977).Hydrologic Engineering Center, Urban Storm-water Runoff ‘STORM, Generalized ComputerProgram 723-58-62520 (Davis, Calif., HydrologicEngineering Center, U.S. Army Corps of Engi-neers, May 1976).Hydrologic Engineering Center, Computer Pro-gram Abstracts (Davis, Calif.: Hydrologic Engi-neering Center, U.S. Army Corps of Engineers,December, 1978).Hydrologic Engineering Center, “Response toOTA Questionnaire: Task Force on Water Re-source Modeling in Federal Agencies, personalcorrespondence, October 1979.Robey, D. L., “Response to OTA Questionnaire:Task Force on Water Resource Modeling in Fed-eral Agencies, personal correspondence, October1979.Roesner, L. A., Nichandros, H. M., and Shubin-ski, R. P., ‘‘A Model for Evaluating Runoff-Qual-ity in Metropolitan Master Planning, technicalpaper No. 58 (Davis, Calif.: Hydrologic Engineer-ing Center, U.S. Army Corps of Engineers, April1974).Walski, Thomas M., “MAPS-A Planning Toolfor Corps of Engineers Regional Water SupplyStudies, ” Water Resources Bulletin, vol. 16, No.2, April 1980.

App. B—Summary of Model Use by Individual Federal Agencies 189

Department of Energy

Office of the Environment

45,

46,

47,

48,

49,

Osterhoudt, Frank H., “Response to OTA Ques-tionnaire: Task Force on Water Resource Model-ing in the Federal Agencies, personal correspond-ence, November 1979.Owen, P. T., Dailey, N. S., Johnson, C. A., andMartin, F. M., ‘ ‘An Inventory of EnvironmentalImpacts Models Related to Energy Technologies,ORNL/EIS-147, February 1979.Shepard, A. D., “A Spatial Analysis Method ofAssessing Water Supply and Demand Applied toEnergy Development in the Ohio River Basin, ”ORNL/TM-6375, August 1979.Shriner, C. R. and Peck, L. J. (eds. ), “Inventoryof Data Bases, Graphics Packages, and Models inDepartment of Energy Laboratories, ” ORNL/EIS-144, November 1978.Shriner, C. R. and Peck, L. J. (eds.), “Water Re-source Management, Planning and Policy Modelsin Department of Energy Laboratories, Novem-ber 1978.

Department of the Interior

Bureau of Land Management

50. Bureau of Land Management, ‘ ‘Water ResourceModeling in the Bureau of Land Management,personal correspondence, 1979.

Bureau of Mines

51.

52.

53.

Bloomsburg, G. L. and Wells, R. D., “SeepageThrough Partially Saturated Shale Wastes: FinalRepor t , contract No. H0252965, September1978.Bureau of Mines, ‘ ‘Response to OTA Question-naire: Task Force on Water Resource Modeling,personal correspondence, November 1979.Hittman Associates, Inc., “Monitoring and Mod-eling of Shallow Groundwater Systems in the Pow-der River Basin: Second Annual Technical Re-port, ” No. H-D0166-78-757F, February 1979.

Office of Water Research and Technology

54. Reefs, Theodore G., ‘ ‘Response to OTA Ques-tionnaire: Task Force on Water Resource Model-ing, ” personal communication, October 1979.

U.S. Fish and Wildlife Service

55.

56.

57.

Hyra, Ronald, ‘ ‘Methods of Assessing InstreamFlows for Recreation, ” FWS/ORS-78/34, Fishand Wildlife Service, Fort Collins, Colo. , June1978.U.S. Fish and Wildlife Service, annotated list ofwater resource models developed for or by the U.S.Fish and Wildlife Service, 1979.U.S. Fish and Wildlife Service, “Response toOTA Questionaire: Task Force on Water Re-source Modeling, personal correspondence, Oc-tober 1979.

U.S. Geological Survey

58.

59.60.

61.

62.

63,

64.

65.

66.

67.

Appel, Charles A., and Bredehoeft, John D.,“Status of Ground-Water Modeling in the U.S.Geological Survey, ” Geological Survey circularNo. 737, 1976.Baltzer, Bob, personal interview, August 1979.Carrigan, Hadley, personal interview, August1979.Faust, Charles R. and Mercer, James W., “Finite-Difference Model of Two-Dimensional Single- andTwo-Phase Heat Transport in a Porous Medium—version 1, U.S. Geological Survey report77-234, 1977.Federal Interagency Work Group on Water Qual-ity Data Needs for Small Watersheds, ‘‘WaterQuality Data Needs for Small Watersheds: Sur-face Water Data, Draft, ’ August 1978.Grove, David B., ‘ ‘Ion Exchange Reactions Im-portant in Groundwater Quality Models, ” sym-posium proceedings, Advances in GroundwaterHydrology, 1976.Jackman, Alan P. and Yotshkura, Nobuhiro,“Thermal Loading of Natural Streams, ” U.S.Geological Survey professional paper 991, 1977.Jennings, Marshall E. and Yotshkura, Nobuhiro,“Status of Surface-Water Modeling in the U.S.Geological Survey, ’ Geological Survey circularNo. 809, 1979.Konikow, Leonard F., “Modeling ChlorideMovement in the Alluvial Aquifer at the RockyMountain Arsenal, Colorado, ” U.S. GeologicalSurvey water supply paper 2044, 1977.Konikow, L. F. and Bredehoeft, J. D., “Com-puter Model of Two-Dimensional Solute Trans-port and Dispersion in Ground Water, USGSbook 7, ch. 2, 1978.


68.

69.

70.71.

72.

73,

74.

75.

76

77.

Konikow, Leonard F., and Bredehoeft, John D.,“Modeling Flow and Chemical Quality Changesin an Irrigated Stream-Aquifer System, WaterResources Research, vol. 10, No. 3, June 1974.Laird, L. B., “Response to OTA Questionnaire:Task Force on Water Resource Modeling in theFederal Agencies, ” personal correspondence,October 1979.Larson, Steve, personal interview, August 1979.McKenzie, Stuart W., et al., “Steady-State Dis-solved Oxygen Model of the Willamette River,Oregon, ” U.S. Geological Survey circular 715-J,1979.Plummer, L. Niel, et al., ‘ ‘ WATEQF-AFORTRAN IV Version of WATER, A ComputerProgram for Calculating Chemical Equilibrium ofNatural Waters, ” USGS, Water Resources Inves-tigations 76-13, September 1976.Trescott, Peter C., ‘‘Documentation of Finite-Dif-ference Model for Simulation of Three-Dimension-al Ground-Water Flow, ” U.S. Geological Surveyreport 75-438, September 1975.Rickert, David A., and Hines, Walter G., “RiverQuality Assessment: Implications of a PrototypeProject, ’ Science, vol. 200, pp. 1113-1118, June1978.Trescott, Peter C., ‘‘Documentation of Finite-Dif-ference Model for Simulation of Three-Dimension-al Ground-Water Flow, U.S. Geological Surveyreport 75-438, September 1975.Trescott, P. C., Pinder, G. F., and Larson, S. P.,‘‘Finite-Difference Model for Aquifer Simulationin Two Dimensions with Results of Numerical Ex-pediments, ” ch. 1, book 7 of Techniques ofWater-Resources Investigations of the U.S. Geo-logical Survey.U.S. Geological Survey, “Computer Programs forModeling Flow and Water Quality of SurfaceWater Systems, ” September 1978.

Bureau of Reclamation

78.

79.

Bureau of Reclamation, ‘‘Response to OTA Ques-tionnaire: Task Force on Water Resource Model-ing, ” personal communication, November 1979.Bureau of Reclamation, “Response to OTA Ques-tionnaire: Task Force on Water Resource Model-ing in Federal Agencies, personal correspond-ence, October 1979; Bureau of Reclamation, Bu-reau of Reclamation Economic Assessment Model(BREAM) Technical Description, January 1978;Ribbens, Richard W., Technical Description ofReturn Flow Quality Simulation Model, Waterand Power Resources Service, January 1980.

Independent Agencies

Council on Environmental Quality

80

81

82

Buffington, J. D., Milask, L. J., “An Overviewof the UPGRADE Data Analysis System.CEQ Executive Summary, response for OTAWater Resources Workshop.C E ~ “ ‘Strawman’ Responses to Objectives ofthe OTA Task Force on Water Resourses Model-ing, “ Oct. 24-25, 1979.

EPA: Office of Research and Development

83.

84.

Office of Research and Development, “Responseto OTA Questionnaire: Task Force on Water Re-source Modeling in Federal Agencies, personalcorrespondence, October 1979.Richardson, W. L., and Thomas. N. A.. “AReview of EPA’s Great Lakes Modeling ‘Pro-gram, ‘‘ in Proceedings of the EPA Conference onEnvironmental Modeling and Simulation, W. R.Ott (cd.), report No., EPA-600/9-76-106 (Cincin-nati, Ohio: Environmental Protection Agency,1976).

EPA: Office of Toxic Substances

85.

86<

87.

Wood, B., “Response to OTA Questionnaire:Task Force on Water Resource Modeling in Fed-eral Agencies, personal correspondence, October1979.Survey and Analysis Division, Office of Toxic Sub-stances, “Response to OTA Questionnaire: TaskForce on Water Resource Modeling in FederalAgencies, personal correspondence, October1979.Zweig, G., “Response to OTA Questionnaire:Task Force on Water Resource Modeling in Fed-eral Agencies, personal correspondence, October1979.

EPA: Office of Water Planning and Standards

88.

89.

90.

Athway, D., and Somers, P., staff, Urban RunoffProgram, Implementation Branch, Water Plan-ning Division, Office of Water Planning andStandards, EPA, personal interview, Aug. 17,1979.Cogger, B., “Response to OTA Questionnaire:Task Force on Water Resource Modeling in Fed-eral Agencies, personal correspondence, October1979.Dupuis, L., staff, Office of Analysis and Evalua-tion, Water Planning and Standards, EPA, per-sonal interview, Aug. 17, 1979.


91.

92.

93

94.

95.

96

Ehreth, D., Callahan, M., Frederick, R., andSlimak, M., staff, Water Quality Analysis Branch,Monitoring and Data Support Division, Office ofWater Planning and Standards, EPA, personal in-terview, Aug. 17, 1979.Myers, C., staff, Implementation Branch, WaterPlanning Division, Office of Water Planning andStandards, EPA, personal interview, Aug. 17,1979.Office of Analysis and Evaluation, “Response toOTA Questionnaire: Task Force on Water Re-source Modeling in Federal Agencies, personalcorrespondence, October 1979.Stuart, T., Chief, Monitoring Branch, Office ofWater Planning and Standards, EPA, personal in-terview, Aug. 17, 1979.Swader, F., staff, Agricultural Runoff Program,Implementation Branch, Water Planning Division,Office of Water Planning and Standards, EPA,personal interview, Aug. 22, 1979.Water Quality Analysis Branch, “Response toOTA Qestionnaire:” Task Force on Water Re-source Modeling in Federal Agencies, personalcorrespondence, October 1979.

EPA: General References

97.

98<

99.

100.

101.

Beckers, C. V., Parker, P. E., Marshall, R. N.,and Chamberlain, S. G., ‘‘ RECEIV-11, A Gener-alized Dynamic Planning Model for Water QualityManagement, in Proceedings of the EPA Confer-ence on Environmental Modeling and Simulation,W. R. Ott (cd.), report No. EPA-600/9-76-100(Cincinnati, Ohio: Environmental ProtectionAgency, 1976).Environmental Protection Agency, ‘‘A StatisticalMethod for the Assessment of Urban Storm-water, report No. EPA 440/3-79-023, preparedfor Environmental Protection Agency, Washing-ton, D. C., May 1979.Falco, J. W., and Mulkey, L. A., “Modeling theEffect of Pesticide Loading on Riverine Ecosys-tems, ‘‘ in Proceeding-s of the EPA Conference onEnvironmental Modeling and Simulation, W. R.Ott (cd.), report No. EPA-600/9-76- 106 (Cincin-nati, Ohio: Environmental Protection Agency,1976).Leytharn, K. M., and Johnson, R. C., “Water-shed Erosion and Sediment Transport Model,Report No. EPA-600/3-79-028, prepared for En-vironmental Protection Agency, Athens, Ga. ,March 1979.Pechan, E. H., and Luken, R. A., “WatershedErosion and Sediment Transport Model, ’ report

102.

103

104

No. EPA-600/3-79-028, prepared for Environmen-tal Protection Agency, Athens, Ga., March 1976.Taylor, P. L., “STORET: A Data Base forModels, ‘‘ in Workshop on Verification of WaterQuality Models, report No. EPA-600/9-80-016,prepared for Environmental Protection Agency,Athens, Ga., April 1980.True, H. A., ‘ ‘Planning Models for Non-PointRunoff Assessment, in Proceedings of the EPAConference on Environmental Modeling and Sim-ulation, W. R. Ott, (cd.), report No. EPA-600/9-76-106 (Cincinnati, Ohio: Environmental Pro-tection Agency, 1976).Versar, Inc., ‘‘ Environmental Assessment of Pri-ority Pollutants: A Review of Evaluative Modelsin Assessing the Fate of Pollutants, Final Report,contract No. 68-01-3852, prepared for Environ-mental Protection Agency, Washington, D.C.February 1979.

National Science Foundation

105. Ezra, A. A., “Executive Summary and ‘Straw-man’ Responses to Objectives of the OTA TaskForce on Water Resource Modeling, ’ Oct. 24-25,1979.

Water Resources Council

106. Walker, Lewis D., Water Supply Adequacy Anal-ysis Model, for the OTA Task Force on Water Re-source Modeling in the Federal Agencies, Oct.24-25, 1979.

General References

107.

108.

109

110,

111,

Brandstetter, A. G., ‘ ‘Assessment of MathematicalModels for Storm and Combined Sewer Manage-m e n t , report No. EPA-600/2-76- 175a, preparedfor Environmental Protection Agency, Cincinnati,Ohio, August 1976.Bugliarello, G., and Gunther, F. C., Devel-opments in Water Science I: Computer Systemsand Water Resources (New York: Elsevier Pub-lishing Co., 1974).Chung, Sang Chu, et al., Computer programs in

Water Resources, Minnesota University WaterResources Research Center, November 1977.Grimsrud, G, Paul, et al., Evaluation of WaterQuality Models: A Management Guide for Plan-ners (Palo Alto, Ca]if.: Systems Control Inc.,1976).Hinson, M. O., and Basta, D. J., “Analyzing Re-ceiving Water Systems, ‘‘ in Analysis for Residuals


112

113

—Environmental Quality Management: Analyz-ing Natural Systems, Resources for the Future,D. J. Basta and B. T. Bower (eds. ), Washington,D. C,, prepared for the Office of Research and De- 114.velopment, Environmental Protection Agency,December 1979.Horton, M. L., et al., Analysis and Dissemination 115.of Water Resources Information, South DakotaState University Water Resources Institute, 1979.Huber, W. C., and Heaney, J. P., “AnalyzingResiduals Generation and Discharges From Urbanand Nonurban Land Surfaces, in Analysis for 116,Residuals-Environmental Quality Management:Analyzing Natural Systems, Resources for theFuture. D. 1. Basta and B. T. Bower (eds.\. Wash-

ington, D. C., prepared for the Office of Researchand Development, U.S. Environmental ProtectionAgency, December 1979.Marks, David H., “Models in Water Resources,in A Guide to Models in Governmental Planningand Operations, EPA, August 1974.U.S. Environmental Protection Agency, Environ-mental Modeling and Simulation, Washington,D. C., Office of Research and Development andOffice of Planning and Management, EPA-600/9-76-016, 1976.Viessman, W., Jr., Knapp, J. W., Lewis, G. L.,and Harbaugh, T. E., Introduction to Hydrology,2d ed. (New York: Harper & Row, 1977).

, “ \ / >

App. B—Summary of Model Use by Individual Federal Agencies 193

ATTACHMENT II. —SURVEY OF FEDERAL AGENCYMODEL USE RELATED TO MAJOR LEGISLATION

July 1 4 , 1 9 8 0

CONGRESS OF THE UNITED STATES

Office of Technology AssessmentWashington, D C 20510

1 .

7. .

3 .


?. . pro~rarn T f t 1 e and l,e~ is la t ive Autbor ~ za t ion——————.—— —.— ——

Fi 11 in the proqram t i tle a t the top of eacb q u e s t i onna ire .P r o v i d e t h e a u t h o r i za t ion i f i t is not on the “a ter ?ro~ramC h e c k l i s t o r otber t h a n a u t h o r i z a t i o n 1 istecl .

3. —- —.—>.—_—.—.-–?.-r~~plete the O~]est i onna ire (s)

A part ia 1 example quest ionna ire is c iven bel ow:

LeCi slat i ve Author 5 za t i on - Puhl ic law Q5-? 17

T’elevant qec t ion ofS p e c i f i c P u r p o s e Law, Rule, Renul a t ion T<ane o f ‘!o Ae 1 (s ~

Act i vitv lfode 1s are Used -or ARency C(I i de 1 i nr— — - . or Cener ic Tvpe— . — — — — . . .——. . ——.— J——.

En fore e Power P l a n t Sect i on 316 t enp. mode 1s~e~u- S i t infi 1!SP and l!n ECWlat ions,St an[la rcls,Cu ide 1 ines

4 . .4c!cI i t i ona 1 Comments - Any add i t i o na 1 c omnc n ts may be wr i t t e n o n———————t h e hack o f t h e Tncl i vidual Pro~ram (?uest i onna i r e s .

I f yotl h a v e a n y q u e s t i o n s ahout t h e s u r v e y , pl e a s e do not hesi tatc t ocal 1 Robe r t F r i edman , P ro j ec t D i r ec to r , a t ( 2n? ) 2?4-7031 .

?1 ease ma i 1 the compl e ted !.!a ter Vropram Checkl i st and Intlividuall’roflram Q u e s t i o n n a i r e ( s ) t o :

-—

IX. Rot~ert ~~. Frje~man

Project DirectorOff ice of TechnoloFv A s s e s s m e n tU . S . ConRressIIashinpton, ~.C. ?(-151~

—

App. B—Summary of Model Use by lndividual Federal Agencies ● 195

PART I : WATER PROGRAM CHECKLIST

- .Co I umn

One

ProgramI n v o l v e -ment

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

L]

[1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

Lo 1 umnTwo

ModelUse

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

FEDERAL WATER POLLUTION CONTROL ACT AMENDMENTS OF 1972(AS AMENDED BY THE CLEAN WATER ACT OF 1977)

Grants for pollution control programs

Mine water pollution control programs

Grants for construction of treatment works

Areawide waste treatment management

Basin planning

Water quality related effluent limitations

Water quality standards and implementation plans

Toxic and pretreatment effluent standards

Oil and hazardous substances liability

Clean lakes

Thermal discharges and exemptions

Guidelines. . . permits for dredged or fill material

Disposal of sewage sludge

SAFE DRINKING WATER ACT

Protection of underground sources of drinking water

Special study and demonstration project grants for wastewater reuse, reclamation and recycling processes

TOXIC SUBSTANCES CONTROL ACT

Testing of chemical substances and mixtures

Regulation of hazardous chemicals and mixtures

Section

S. 106

s. 107

s. 201

S. 208

S. 209

S. 302

s. 303

s. 307

s. 311

s. 314

S. 316

s. 404

s. 405

S. 1421

s. 1444

s. 4

S. 6

196 ● use of Mode/s for water Resources Management, planning, and Policy

Column ColumnOne Two

ProgramInvolve- Modelment Use

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

RESOURCE CONSERVATION AND RECOVERY ACT

Solid waste management guidelines

Ident i f i ca t ion and l i s t ing o f hazardous wastes

Standards for owners and operators of hazardoust r e a t m e n t , s t o r a g e a n d d i s p o s a l f a c i l i t i e s

Page 2

Section

S. 1008

s. 3001

waste

Consolidated permits for hazardous waste managementfacilities

Grants for state resource recovery and conservation

Full scale demonstration facilities grants

Resource recovery systems and improved solid wastedisposal facilities

ENDANGERED SPECIES ACT

Minimizations of impacts of Federal activitiesmodifying critical habitats

SURFACE MINING CONTROL AND RECLAMATION ACT

Surface coal mine reclamation permitting

Environmental protection performance standards forsurface coal mine reclamation

SOIL AND WATER RESOURCE CONSERVATION ACT OF 1977

Data collection about soil, water and relatedresources

Soil and water conservation programs

WATER RESOURCES PLANNING ACT

s. 3004

s. 3005

plans S. 4008

S. 8004

s. 8006

s. 7

S. 506

s. 515

s. 5

S. 6

Regional or river basin plans and programs and theirrelation to larger region requirements s. 102

Coordinating Federal water and related land resourcesprograms and policies s. 102


Page 3

Column ColumnOne Two

ProgramInvolve- Modelment Use Section

COASTAL ZONE MANAGEMENT ACT

[1 [1 State coastal zone land and water resources managementprogram development and management grants s. 305

EXECUTIVE ORDER 11988

Floodplain management S. 2&3[1 [1

FLOOD CONTROL ACT OF 1936 AND AMENDMENTS

Flood control structures S. 1,2,3[1 [ 1

WATER RESOURCES DEVELOPMENT ACT OF 1974

Nonstructural measures[1 [ 1 s. 73

FEDERAL RECLAMATION ACT OF 1902 AND AMENDMENTS

Irrigation distribution systems

Construction of small projects

[1

[1

[ 1

[1

(43 U.S.C. 421)

(43 U.S.C. 422)

OTHER ACT

Other Programs[1

[ 1

[1

[1 s.

s.

s.[1

[1

OTHER ACT

[1

[1

[1

[1

[1

[1

Other Programs s.

s.

s.


PART I I : INDIVIDUAL PROGRAM QUESTIONNAIRE

PROGRAH Respondent(fill inonly one program on each Questionnaire)

— — — — —

OffIce

Legislative authorization Agency(If not on OTA program list or other than

— — — — —

authfi~zation listed on Water Program Checklist) Phone Number

●

Relevant Section of Law,Actlvlties Specific Purposes for which Models are Used Rule, Regulation or Name of Model(s

Agency Guideline or Generic Type—

Program Planningand Scope

Promulgate Regulations,Set Standards, OevelopGuidelines

Enforce Regulations,Standards, Guidelines

Comply with Regulations,Standards, Guidelines

Plan or EvaluateProjects, Activities

Allocate Plannlng orConstructIon Funds

State or LocalAdvisory Assistance

Operation and Management

Other Program Activities

.

.

Appendix C

Summaries of Related Modeling Studies

This appendix summarizes five previously completedstudies of model development, use, and dissemination—three conducted wholly within the United States, onefrom Canada, and one international assessment. Thefive were chosen for their currency and relevance to theissues raised in this report, and largely corroborate OTAfindings regarding current modeling issues. They are:

1.

2.

3.

4.

5.

“Federally-Supported Mathematical Models: Sur-vey and Analysis, National Science Foundation(NSF), 1974.“Ways to Improve Management of Federally-Funded Computerized Models, ” General Ac-counting Office (GAO), 1976.‘‘A Study for Assessing Ways to Improve the Utili-ty of Large-Scale Models, ’ National Bureau ofStandards (NBS), 1978.“Survey of Environmental Management Simula-tion Models in Canada, ’ R. D. Miller.“SCOPE International Assessment Project onGroundwater Model Modeling”

1. “Federally-Supported MathematicalModels: Survey and Analysis” (Fromm,Hamilton, & Hamilton)

This survey was completed in 1974 by NSF. It sur-veyed a universe of over 650 models which addressedsome aspect of social decisionmaking, and which wereused by or developed for nondefense Federal agencies.Responses were received for 222 models, from over 230project directors and 80 Federal agency monitors.

Respondents indicated that the most important con-straints limiting model utility were: 1 ) data availabil-ity, and 2) ease of use by nontechnicians. Responses alsoindicated a prevailing tendency for actual use of modelsto fall short of intended use. Policy-related model usesappeared to have the greatest shortfall—between one-third and two-thirds of the models failed to achieve theirstated purposes with respect to direct application to pol-icy problems.

Based on survey responses, staff attributed low policyutilization rates for models primarily to lack of commu-nication between model builders and potential policy-makers during model development, and secondarily topolicy makers’ limited capabilities to use models oncethey had been developed. The study found very littleinteraction between developers and users during modeldevelopment— actual briefings were held in only 19 per-cent of the projects, and user agencies ran models andanalyzed results in only 34 percent; written reports alone

were provided in over 50 percent of surveyed modelingprojects. Most of the projects were supported by grants,with very infrequent specification of performance re-quirements or desired detail and characteristics by thefunding agency.

The survey identified two dimensions to the “easeof use” problem: 1) decisionmaker understanding ofmodels, and 2) the adequacy of developer-supplied in-structions for operating the model. Both developers andagency personnel noted that policy makers frequentlylack the training that would equip them to use modelsappropriately. On the other hand, in about 75 percentof the surveyed cases, the documentation supplied bythe developer was considered inadequate to enable non-project personnel to set up and run the model. The ma-jority of the documentation efforts failed to include usermanuals, operating instructions, or computer programs.Use rates were found to be highest for models havinguser manuals; these tended to be produced when fund-ing agencies specified desired model characteristics, andwhen funding was carried out under contracts ratherthan grants.

2. “Ways to Improve Management ofFederally-Funded Computerized Models”

This 1976 survey conducted by GAO was based onresponses to questionnaires regarding 519 federallyfunded models developed and/or used in the U.S. PacificNorthwest. Fifty-seven of those models costing over$100,000 to develop were selected for detailed review—and 33 of these were described by respondents as hav-ing encountered ‘‘major problems’ in development.GAO characterized these problems as being due to:

. inadequate management planning (70 percent);

. inadequate management commitment (15 percent);and

● inadequate management coordination (15 percent).GAO found that model development problems tended

to result in models not being used once they are devel-oped, cost overruns for models, and prolonged develop-ment time, The reasons most frequently given for modeldevelopment problems were: 1) the unreliability of mod-el results, 2) developers’ inability to obtain necessarydata, and 3) users’ failure to allocate enough funds tocomplete the model. GAO further outlined developmentproblems stemming from deficiencies in managementplanning, commitment, and coordination:

● Problems attributable to inadequate managementplanning:

199


— Management did not clearly define the problemto be modeled; thus, the developer had to guesswhat had to be modeled.

— The developer was not able to obtain the dataneeded to make the model function.

— Management allocated insufficient funds tocomplete the model.

— Management did not make workable provisionsfor updating the model for future use; thus, themodel soon began to produce outdated informa-tion.

— Management did not make provisions for evalu-ating the model.

— Management did not clarify documentation re-quirements for the model. As a result, only thedeveloper understood how it worked and the re-lationship maintained by the variables incor-porated into it.

● Problems attributable to inadequate managementcommitment:— Management did not actively participate in

planning of the model. Thus, the model did notclearly reflect their needs.

— Management did not understand computermodeling techniques and applications. Conse-quently, they could not effectively use informa-tion obtained from the models.

● Problems attributable to inadequate managementcoordination:— Management did not monitor the model devel-

opment effort on a cent continuous basis. Thus,management allowed development efforts tocontinue after they should have been termi-nated.

— Managers did not coordinate the developmenteffort with the developer. As a result, the modelwas developed without reasonable assurancethat it would meet user needs.

Two major solutions for these problems were pro-posed in the GAO report: First, the use of a phased ap-proach to model development, requiring the fundingagency to review projects and decide whether to con-tinue development at the end of each of five stages:1) problem definition, 2) preliminary design, 3) detaildesign, 4) evaluation, and 5) maintenance. This sug-gested procedure is seen as promoting a more thoroughearly investigation of the nature of the problem and ofpossible solution methods, as well as providing a methodof controlling commitments to modeling efforts.

GAO’s second proposal was that the Department ofCommerce and the General Services Administration,using their respective authorities under the Brooks Act(Public Law 89-306), formulate Government-widestandards and guidance on developing and procuring

computerized models, and coordinate with other Federalagencies to obtain advice regarding such standards andguidance.

3. “A Study for Assessing Ways to Improvethe Utility of Large-Scale Models”(S. I. Gass, Z. F. Landsdowne,R. P. Harvey, and A. J. Lemonine)

This study, completed in December 1978 for NBS,surveyed a group of modelers selected for their recog-nized expertise and their interest in the modeling pro-fession. Of 57 modelers who were requested to partici-pate, 39 responded, yielding the following cross-sectionof affiliations and expertise:Affiliation ExpertiseUniversity 8 Analytic . . . . . . . . . .......19Not-for-profi[ . . . . . . 8 Simulation . . . . . . . .. ....12Profit . . . . . 9 Economics . . . . . 9Government . . . . . . .*

T o t a l . . . . . . . . . . . . 3 9 Total . . . . . . . . . . . . . ~

These participants, responding to propositions andstatements in 18 model improvement area categories,gave highest priority to proposals to clarify the relation-ship between model developer and user, and increasethe interaction between them. Strongest support wasvoiced for such specific proposals as:

1.

2.

3.

4

5.

Model developers should specify a documenta-tion plan in their contract, detailing the documentsto be produced, the resources allocated, and per-sonnel responsibilities.The Federal Government should establish a flexi-ble set of model documentation guidelines that canbe used by model developers and sponsors to createa project’s documentation plan.Requests for proposals (RFPs) should indicate theultimate user of the model, and require meetingsbetween model developers and users to aid in de-signing models to meet user requirements.Model developers should be required to prepareverification and validation test plans, report resultsof the tests, and describe their implications for fu-ture use of their models.Model forums should be established by profession-al organizations, industrial groups, and-the Feder-al Government.

Participants also indicated strong support for coordi-nated model development and data collection. They sup-ported mandatory data availability and costing assess-ments prior to the issuance of an RFP for a model, andrequirements for parallel data collection efforts to bespecified in the ‘ ‘scope of work ‘‘ if necessary data arenot already available.

Moderate support was also expressed for: 1) requir-ing greater specificity in the RFP statement of work,

App. C—Summaries of Related Modeling Studies ● 201

including explicit statements of model scope and objec-tives; 2) Federal exploration of phased management ap-proaches to model development; and 3) requiring allmodel development contracts to address the issue of usertraining.

Participants strongly disapproved of centralized Gov-ernment-sponsored review and analysis relating to mod-els, specifically rejecting model clearinghouses; a modeltesting, verification, and validation center; and a Gov-ernment modeling research center.

4. “Survey of Environmental ManagementSimulation Models in Canada”(R. D. Miller)

Simulation modelers in Canada who were involvedwith developing environmental management modelswere requested to complete questionnaires regarding themodels they had developed. Questions were directed to-ward

1.

2.

3.

4.

5.

five general areas:purpose of the model, including the audience towhich it was directed;degree of success, including implementation of themodel and its use in decisionmaking;problems encountered during model developmentand implementation;planning and managerial factors that might serveas predictors of success; andtechnical details of how the simulation was car-ried out.

The overall results of the survey suggest that the sur-veyed model development projects suffered from lackof involvement and meaningful contribution by deci-sionmakers in the early stages of model development.A lack of user credibility accorded to the model was re-ported only in cases where users had not been involvedin managing the project. In these cases, user credibil-ity was cited as a problem with far greater frequencythan the modeler’s willingness to help, suggesting thatmodelers neglect to involve decisionmakers more oftenthan decisionmakers refuse to consider the advantagesof developing models.

Specific correlations were found between:perceived success and attempts to involve users atearly stages of development, specifically by givingsystem managers some voice in managing the simu-lation project;perceived success and preproject literature searchesor state-of-the-art surveys;perceived success and intended audience. Caseswhere model output was to be used by technicalor research staff had a significantly better successlevel than cases where model results were to be usedby policy formulation groups, or middle- or high-level management; and

● model purpose and difficulties encountered duringthe project. Where models were constructed pri-marily for research purposes, lack of understandingof mechanisms, and lack of available data, weremost often cited as problems; where models wereintended for policy recommendations, lack of usercredibility was the most frequently named problem.

5. “SCOPE International Assessment Projecton Groundwater Model Modeling’

The SCOPE project was carried out between 1975and 1977, primarily through surveys of two groups:1) active model developers, and 2) those active inapplying models to management problems. Reports onapproximately 250 models were submit ted in responseto the project survey.

The purpose of the assessment was to provide guid-ance on measures for improving the utility of modelsin ground water management. Four major problemareas were identified during the course of the project,and were ranked by project staff and an internationalsteering committee in the following order of importance:

1. accessibility of models to users;2. communications between managers and technical

personnel;3. inadequacies of data; and4. inadequacies of modeling.The survey found difficulties in gaining access to exist-

ing models to be the most serious impediment to effec-tive use of models in ground water management. Majorproblems of accessibility revolve around the usabilityof model documentation, model distribution, adequatetraining in the use of models, and user certification.Project staff suggested that improvements in these areaswould require shifts in the incentive structures of institu-tions, or even modifications to the institutions them-selves. Their primary recommendation involved estab-lishing public agency requirements for adequate docu-mentation as a prerequisite for funding any model devel-opment effort.

To improve communication between managers andtechnical personnel, the study staff recommended meas-ures to increase interactive participation in problem def-inition and model application, so that managers becomedirectly involved in developing the models they commis-sion. Additional recommendations included designingmodel outputs to be easily understandable by nontechni-cal personnel, and encouraging further development ofmanagement “decisionmaking” models.

Data-gathering recommendations stressed improvedmethods for routine data collection, storage, and retriev-al, and sensitivity analysis as a method of determiningthe most critical data needs for modeling purposes.

. .- I .r{ - 11,

Appendix D

Additional References to Modelsand Modeling Studies

Surface Water Flow andSupply References

Table of Model Types (withreference numbers)

General (50, 54, 66, 75, 82, 86, 112)1.

2.

3.

4.

5.

6.7.

8.

9.10.

11.12.13.14.15.

16.17.

18.

19.

20.

21.22.23.

24.

202

Watershed Soil/Water Process Models (5, 7, 9, 16,18, 19, 23, 40, 41, 43, 53, 57, 59, 61, 88, 91, 95,97, 98, 104, 108, 116, 117, 118, 119)Snow Accumulation and Melt Models (1, 2, 3, 9,16, 23, 40, 41, 43, 53, 59, 61, 98, 106, 118, 119)Baseflow Models (5, 7, 9, 16, 19, 23, 34, 40, 41,43, 52, 53, 57, 59, 61, 88, 98, 117, 118, 119)Channel Routing Models (5, 9, 16, 18, 19, 28, 40,41, 43, 47, 74, 91, 95, 97, 98, 104, 108, 119)Lake and Reservoir Routing Models (19, 43, 47,57, 97, 98)Flood Formulae (24, 32, 37, 39,62, 73,80,93, 108)Regional Flood Equations (24, 26, 48, 62, 64, 73,87, 92, 115)Regional Flood Simulation Models (24, 45, 62, 65,125)Flow Frequency Models (73, 78, 85)Evapotranspiration Models (5, 9, 16, 18, 19, 23,31, 40, 41, 43, 53, 57, 58, 59, 60, 61, 76, 77, 83,91, 96, 97, 98, 107, 116, 117, 118, 119)Unit Hydrography Models (22, 24, 39, 62, 94, 108)Dam Failure Models (5, 10, 44)Reservoir Water Accounting Models (9, 57, 98)Annual Data Generation Models (27, 67,68,69, 79)Regional Data Generation Models (20, 26, 36, 51,64, 70, 79, 87, 111)Reservoir Sedimentation Models (8, 15, 57, 98)Ice Formation and Breakup Models (21, 25, 33, 71,72, 81, 89, 102, 103, 120)Freezing and Breakup Formulae (12, 21, 25, 33, 72,81, 89, 102, 103, 120)Plot Size Soil/Water Process Models (29, 31, 53,57, 58, 59, 60, 61, 88, 95, 96, 108)Plot Snow Accumulation and Melt Models (31, 53,59, 60, 61, 96)Bank Sloughing Models (109)Flood Inundation Models (46)Channel Erosion and Deposition Models (4, 84, 90,101, 105)Channel Geometry Equations (63, 99)

25. Irrigation Water Demand Models (57, 100)26. Land Drainage Models (49, 57, 110, 114)2728.29.30<

31,

32,

1.

2.

3

4.

5.

6.

7.

8.

9.

(11

Conduit Capacity Models ( 11)Pipe Network Models (56, 113)Regional Water Use Relationships (30, 42)Annual Use Generation Models (17)Plant Water Use Models (6, 13, 14, 35, 38, 55, 76,77, 83, 107)System Water Need Models (56)

References

Anderson, E. A., ‘ ‘The Synthesis of ContinuousSnowmelt Runoff Hydrography on a Digital Com-puter, technical report 36, Department of CivilEngineering, Stanford University, Stanford,Calif., 1964.

, “National Weather Service River Fore-cast System: Snow Accumulation and AblationModel, ” NOAA technical memorandum, NWSHYDRO- 17, Department of Commerce, SilverSpring, Md., 1973.

> “A Joint Energy and Mass Balance Mod-el of a Snow Cover, NOAA technical report,NWS 19, Department of Commerce, SilverSpring, Md., 1976.Beer, C. E., and Johnson, H. P., “Factors Relatedto Gully Growth in the Deep Loess Area of West-ern Iowa, ” Department of Agriculture, miscellane-ous publication 970, 1965, pp. 37-43.Betson, R. P., ‘‘A Continuous Daily StreamflowM o d e l , TVA research paper No. 8, Knoxville,Term., 1972.Blaney, H. F., and Griddle, W. D., “Determin-ing Water Requirements in Irrigated Areas FromClimatological and Irrigation Data, ” Departmentof Agriculture, Soil Conservation Service, TP-96,1950.Bowles, D. S., and Riley, J. P., “Low Flow Mod-eling in Small Steep Watersheds, Journal ofthe Hydraulics Division, proceedings of ASCE102( HY9):1225- 1239, 1976.Brune, G. M., ‘ ‘Trap Efficiency of Reservoirs,Transactions of the American Geophysical Union,34(3):407-418, 1953.Burnash, R. J. C., Ferrall, R. L., and McGuire,R. A., “A Generalized Streamflow Simulation

App. D—Additjonal References to Models and Modeling Studies ● 203

10

11.

12.

13.

14

15

16.

17.

18.

19.

20.

21

22.

23.

System: Conceptual Modeling for Digital Comput-e r s , unnumbered publication, California Depart-ment of Water Resources, 1973.Chen, C-L, and Armbruster, J. T., Darn-BreakWave Model: Formulation and Verification, pro-ceedings of ASCE, 106( HY5):747-768, 1980.Chow, V. T., Open Channel Hydraulics (NewYork: McGraw-Hill, 1959).

Handbook of Applied Hydrology (NewYork: McGraw-Hill, 1964).Christensen, J. E., ‘ ‘Pan Evaporation and Evapo-transpiration From Climatic Data, proceedingsof ASCE, 94( IR2):243 .265, 1968.Christensen, J. E., and Hargreaves, G. H., “Irri-gation Requirements From Evaporation, Inter-national Commission on Irrigation and Drainage,Seventh Congress, 25.569-23.596, 1970.Churchill, M. A., “Discussion of ‘Analysis andUse of Reservoir Sedimentation Data, by L. C.Gottschalk, proceedings of the Federal Inter-agency Sedimentation Conference, Denver, CO1O.,1945, pp. 139-140 (published by Department of theInterior, Bureau of Reclamation, Denver).Crawford, N. H., and Linsley, R. K., “DigitalSimulation in Hydrology: Stanford WatershedModel IV, ” technical report 39, Department ofCivil Engineering, Stanford University, Stanford,Calif., 1966.Cruz, S-L, and Yevjevich, V., “Stochastic Struc-ture of Water Use Time Series, Colorado StateUniversity hydrology paper No. 52, 1972.Dawdy, D. R., Lichty, R. W., and Bergman,J. M., ‘‘A Rainfall-Runoff Simulation Model forEstimation of Flood Peaks for Small DrainageBasins, U.S. Geological Survey professionalpaper 506-6 (Washington, D. C.: U.S. Govern-ment Printing Office, 1972).Dawdy, D. R., Schaake, Jr., J. C., and Alley,W. M., “Distributed Routing Rainfall-RunoffModel, ” U.S. Geological Survey Water ResourcesInvestigations 78-90, 1978.DeWalle, D. R., and Rango, A., “Water Re-sources Applications of Stream Channel Charac-teristics on Small Forested Basins, Water Re-sources Investigations 78-90, 1972.Dilley, J. F., “Lake Ontario Ice Modeling, ”IFYGL Phase 3, General Electric Co., Philadel-phia, Pa., NTIS PB-264 998, 1976.Dooge,, J. C. I., ‘ ‘Linear Theory of HydrologicSystems, ’ Department of Agriculture TechnicalBulletin 1468 (Washington, D. C.: U.S. Govern-ment Printing Office, 1973).Eggleston, K. O., Israelsen, E. K., and Riley,J. P., ‘ ‘Hybrid Computer Simulation of the Ac-

24

25.

26.

27

28.

29.

30.

31.

32.

33.

34.

35.

36.

37

cumulation and Melt Process in a Snowpack,Utah Water Research Laboratory PublicationPRWG65-1, 1971.Eychaner, J. H., “Estimating Runoff Volumesand Flood Hydrography in the Colorado River Ba-sin, Southern Utah, U.S. Geological Survey Wa-ter Resources Investigations 76-102, 1976.Ficke, E, R., and Ficke, J. F., “Ice on Rivers andLakes: A Bibliographic Essay, ” U.S. GeologicalSurvey Water Resources Investigations, 1977.Fields, F. K., ‘‘Estimating Strearnflow Character-istics for Streams in Utah Using Selected Channel-Geometry Parameters, ” U.S. Geological SurveyWater Resources Investigations 34-71, NTISPB-241 541, 1975.Fiering, M. B., and Jackson, B. B., SyntheticStreamflows, Water Resources Monograph 1,American Geophysical Union, Washington, D. C.,1971.Fread, D. L., ‘ ‘Technique for Implicit DynamicRouting in Rivers and Tributaries, ” Water Re-sources Research 9(4):918-926, 1973.Gifford, G. F., and Hawkins, R. H., “Determinis-tic Hydrologic Modeling of Grazing System Im-pacts on Infdtration Rates, ” Water Resources Bul-letin 15(4):924-934, 1979.Gleason, G. B., “Consumptive Use in Municipaland Industrial Areas, proceedings of ASCE 77,separate No. 99, 1951.Goldstein, R. A., Mankin, J. B., and Luxmore,R. J., “Documentation of PROSPER: A Modelof Atmosphere-Soil-Plant Water Flow, EDFB-IBP-73-9, Oak Ridge National Laboratory, OakRidge, Term., 1974.Grunsky, C. E., “Rain and Runoff Near SanFrancisco, California, ” transactions of ASCE,1090, 1908.H. G. Acres, Ltd, “Review of Current Ice Tech-nology and Evaluation of Research Priorities,report to Inland Waters Branch, 105, EnvironmentCanada, 1971.Hall, F. R., “Base-Flow Recessions: A Review.Water Resources Research, ” 4(5):973-983, 1968.Hargreaves, G. H., ‘ ‘Consumptive Use DerivedFrom Evaporation Pan Data, proceedings ofASCE, 94( IR1):97-105, 1968.Hedman, E. R., “Mean Annual Runoff asRelated to Channel Geometry of Selected Streamsin California, U.S. Geological Survey WaterSupply report 1999-E (Washington, D. C.: U.S.Government Printing Office, 1970).Helvey, J. D., “Interception by Eastern WhiteP i n e , Water Resources Research, 3(3):723-729,1967.


38.

39.

40.

41.

42.

43.

44.

45.

46,

47.

48.

49.

50

51

52.

53.

54.

Hendricks, D. W., and Hansen, V. E., “Mechan-ics of Evapotranspiration, transactions of ASCE,128 (111):422-443, 1962.Hewlett, J. D., Cunningham, G. B., and Troen-dle, C. A., “Predicting Stormflow and PeakflowFrom Small Basins in Humid Areas by the R-Index Method, ” Water Resources Bulletin, 13(2):231-253, 1977.Holtan, H. N., and Lopez, N. C., “USDAHL-70Model of Watershed Hydrology, ” U.S. Depart-ment of Agriculture Technical Bulletin 1435, 1971.

, ‘‘USDAHL-73 Revised Model of Water-shed Hydrology, Department of AgriculturePlant Physiological Institute report 1, 1973.Hughes, T. C., and Gross, R., “Domestic WaterDemand in Utah. Utah Water Research Labora-tory report UWRL/P-79/04, 1979.Hydrocomp, Inc., “Hydrocomp Simulation Pro-graming Operations Manual, ” Hydrocomp, Inc.,Palo Alto, Calif., 1969.

“FULEQ Full Equations HydraulicsDam Failure, ” Palo Alto, Calif., 1976.

“Planning and Modeling in Urban WaterManag~ment, Palo Alto, Calif., 1978.Hydrologic Engineering Center, ‘‘HEC-2, WaterSurface Profiles: User’s Manual, ” U.S. ArmyCorps of Engineers, Davis, Calif., 1972.

‘‘HEC-5C, Reservoir System Operationfor Flood Control and Conservation, U.S. ArmyCorps of Engineers, Davis, Calif., 1975.Hydrology Committee, Water Resources Council,‘ ‘Guidelines for Determining Flood Flow Frequen-cy, ” bulletin 17, 1976.International Institute for Land Reclamation andImprovement, Drainage Principles and Applica-tions, publication No. 16, 4 vols., Wajeninen,Netherlands, 1972.James, D. E. (cd.), U.S. National Report to theIUGG, American Geophysical Union, Washing-ton, D. C., 1979.James, L. D., Bowles, D. S., James, W. R., andCanfield, R. V., Estimation of Water Surface Ele-vation Probabilities and Associated Damages forthe Great Salt Lake, Utah Water Research Lab-oratory publication UWRL/P-79/03, 1979.James, L. D., and Thompson, W. O., ‘‘ LeastSquares Estimation of Constants in a Linear Re-cession Model, ” Water Resources Research, 6(4):1062-1069, 1970.Jaynes, R. A., ‘‘A Hydrologic Model of Aspen-Conifer Succession in the Western United States. ”Department of Agriculture Forest Service researchpaper INT213, 1978.Jennings, M. E., and Yotsukura, N., ‘‘ Status ofSurface-Water Modeling in the U.S. Geological

55.

56.

57.

58.

59.

60.

61.

62.

63.

64.

65.

66.

67.

68.

69.

Survey, ” U.S. Geological Survey circular 809,1979.Jensen, M. E., and Haise, H. R., ‘ ‘EstimatingEvapotranspiration From Solar Radiation, pro-ceedings of ASCE, 89( IR4): 15-41, 1963.Jeppson, R. W., Analysis of Flows in Pipe Net-works, Ann Arbor Science, 1976.Knisel, W. G. (cd.), CREAMS: A Field ScaleModel for Chemicals, Runoff and Erosion FromAgricultural Management Systems, Departmentof Agriculture Conservation Research Report 26,1980.Larson, N. M., and Reeves, M., “Analytic Anal-ysis of Soil-Moisture and Trace ContaminantTransport, ” Oak Ridge National Laboratory re-port ORNL/NSF/EATC-12, undated.Leaf, C. F., and Alexander, R. R., “SimulatingTimber Yields and Hydrologic Impacts ResultingFrom Timber Harvest on Subalpine Watersheds,1975.Leaf, C. F., and Brink, G. E., “Computer Simu-lation of Snowmelt Within a Colorado SubalpineWatershed, Department of Agriculture ForestService research paper RM-99, 1973.

7 “Hydrologic Simulation Model of Colo-rado Subalpine Forest, Department of Agricul-ture Forest Service research paper RM-107, 1973.Lee, B. H., Reich, B. M., Rachford, T. M., andAron, G., “Flood Hydrograph Synthesis for RuralPennsylvania Watersheds, ” Department of CivilEngineering, Pennsylvania State University, 1974.Leopold, L. B., and Maddock, T. G., “The Hy-draulic Geometry of Stream Channels and SomePhysiographic Implications, ” U.S. Geological Sur-vey professional paper 252, 1953.Lowham, H. W., “Techniques for EstimatingFlow Characteristics of Wyoming Streams, U.S.Geological Survey Water Resources Investigations76-112, 1976.Lumb, A. M., and James, L. D., “Runoff Filesfor Flood Hydrography Simulation, proceedingsof ASCE, 102 (HY1O): 1515-1531, 1976.McCuen, R. H., Rawls, W. J., Fisher, G. T., andPowell, R. L., ‘ ‘Flood Flow Frequency for Un-gaged Watersheds: A Literature Evaluation, De-partment of Agriculture, Agriculture ResearchService, ARS-NE-86, 1977.Mandelbrat, B. B., ‘‘A Fast Fractional GaussianNoise Generator, Water Resources Research,7(3):543-553, 1971.

“Broken Line Process Defined as an Ap-proxim~tion to Fractional Noise, Water Re-sources Research, 8(5): 1354-1356, 1972.Mejia, J. M., Rodriguez-Itunbe, 1., and Dawdy,D. R., ‘‘Streamflow Simulation 2: The Broken

App. D—Additional References to Models and Modeling Studies ● 205

70.

71.

72.

73.

74.

75.

76.

77.

78.

79.

80.

81.

82.

83.

84<

Line Process as a Potential Model for HydrologicSimulation, Water Resources Research, 8(4):931-941, 1972.Mejia, J. M., and Rousselle, J., “DisaggregationModels in Hydrology Revisited, ” Water Re-sources Research, 12(2): 185-186, 1976.Muller, A., ‘‘Frazil Ice Formation in TurbulentFlow, ‘‘ report No. 214, Iowa Institute of HydraulicResearch, Iowa City, Iowa, 1978.Muller, A., and Calkins, D. J., “Frazil Ice For-mation in Turbulent Flow, ” proceedings of IAHRSymposium on Ice Problems, Lulea, Sweden, vol.II: 219-234, 1978.National Environmental Research Council, FloodStudies Report, Volume I: Hydrological Studies,London, England, 1975.

Flood Studies Report, Volume II; FloodRouting Studies, London, England, 1975.Nieber, J. L., Walter, M. F., and Black, R. D.,‘‘A Review and Analysis of Selected HydrologicModeling Concepts, OWRT completion report,project No. A-061-NY, 1975.Nimah, M. N., and Hanks, R. J., “Model forEstimating Soil, Water, Plant, and AtmosphericInterrelations, 1: Description and Sensitivity, ”proceedings of SSSA, 37:522-527, 1973a.

‘ ‘Model for Estimating Soil, Water,Plant, and Atmospheric Interrelations, 2: FieldTest of Model, ” proceedings of SSSA, 37:528-532,1973b.North, M., ‘ ‘Time Dependent Stochastic Modelof Floods, ” proceedings of ASCE, 106(HY5):649-665, 1980.O’Connell, P. E., “Stochastic Modeling of Long-Term Persistence in Streamflow Sequences, ” in-ternal report, Hydrology Section, Civil Engineer-ing Department, Imperial College, London, 1974.01’ deKop, E. M., ‘ ‘On Evaporation From theSurface of River Basins, Tr. IUr’ev Obs. Lenin-grad, 1911 (cited in Sellars, 1965).Osterkamp, T. E., ‘‘Frazil Ice Formation: A Re-v i e w , proceedings of ASCE, 104( HY9): 1239-1256, 1978.Peck, E. L., Bochin, N. A., Kouzel, A., Lennox,D. H., and Sundblad, B. (eds. ), State of the Artin Transposable Watershed Models, proceedingsof Third Northern Research Basin SymposiumWorkshop, International Hydrological Program,Quebec City, 1979.Penman, H. L., “Natural Evaporation FromOpen Water, Bare Soil, and Grass, ” proceedingsof Royal Society of London, Series A 193: 120-145,1948.Pfankuch, D. J., ‘ ‘Stream Reach Inventory andChannel Stability Evaluation, ” Department of Ag-

85.

86.

87

88

89.

90.

91.

92.

93.

94.

95.

96.

97

riculture Forest Service, Region 1, Missoula,Mont., 1975.Rae, D. V., ‘ ‘Log Pearson Type 3 Distribution:A Generalized Evaluation, ” proceedings of ASCE,106( HY5):853-872, 1980.Renard, K. G., Rawls, W. J., and Fogel, M. M.,“Currently Available Models, ” ch. 13 in Hydro-logic Modeling of Small Watersheds, ASAE mono-graph, St. Joseph, Mich., 1980.Riggs, H. C., ‘‘Streamflow Characteristics FromChannel Size, ” proceedings of ASCE, 104( HY1):87-96, 1978.Riley, J. P., and Hawkins, R. H., “HydrologicModeling of Rangeland Watersheds, ” in Water-shed Management on Range and Forest Lands,proceedings of the Fifth Workshop of the UnitedStates/Australia Rangelands Panel, Boise, Idaho,published by Utah Water Research Laboratory,1975.Rogers, J. C., “Evacuation of Techniques forLong Range Forecasting of Air Temperature andIce Formation, NOAA technical memorandumERL GLERL-8, 1976.Rosgen, D. F., “Mass Wasting, ” ch. III inWRENS: U.S. Forest Service Report to EPA,agreement EPA-IAG-D6-0060, Review Draft.Ross, B. B., Shanholtz, V. O., Contractor, D. N.,and Carr, J. C., ‘‘A Model for Evaluating the Ef-fect of Land Uses on Flood Flows, ” bulletin 85,Virginia Water Resources Research Center, 1975.Saah, A. D., et al., ‘ ‘Development of Regional Re-gression Equations for Solution of Certain Hydro-logic Problems in and Adjacent to Santa ClaraCounty, ” Santa Clara Valley Water District, SanJose, Calif., 1976.Sellars, W. D., Physical C)imato]ogy, Universityof Chicago Press, 1965.Sherman, L. K., ‘ ‘Stream-Flow From Rainfall bythe Unit-Graph Method, Engineering News-Record, 108:501-505, 1932.Simons, D. B., Li, R. M., and Stevens, M. A.,‘ ‘Development of a Model for Predicting Waterand Sediment Yield From Storms on Small Water-sheds, Department of Agriculture Forest Service,Rocky Mountain Forest and Range ExperimentStation, Flagstaff, Ariz., 1975.Solomon, R. M., Ffolliott, P. F., Baker, Jr., M.B., and Thompson, J. R., “Computer Simulationof Snowmelt, Department of Agriculture ForestService research paper RM-174, 1976.Spencer, D. W., and Alexander, T. W., “Tech-nique for Estimating the Magnitude and Frequen-cy of Floods in St. Louis County, Missouri, U.S.Geological Survey Water Resources Investigations78-139, 1978.


98.

99.

100.

101

102.

103.

1044

105 4

106.

107.

108,

109.

110.

111,

1124

Staff, Hydrologic Research Laboratory, “NationalWeather Service River Forecast System, ForecastP r o c e d u r e s , NOAA technical memorandumNWS HYDRO-14 and HYDRO-17, Departmentof Commerce, Silver Spring, Md., 1972.Stall, J. B., and Fok, Y. S., “Hydraulic Geometryof Illinois Streams, ’ University of Illinois WaterResources Center research report 15, 1968.Stewart, J. I., et al., “Optimizing Crop Produc-tion Through Control of Water and Salinity Levelsin the Soil, Utah Water Research Laboratorypublication PRWG151-1, 1977.Swanson, J. F., and Swanston, D. N., “A Con-ceptual Model of Solid Mass Movement SurfaceSoil Erosion and Stream Channel Erosion Proc-esses, ” Coniferous Forest Biome Erosion Model-ing Group, biome report No. 72, 1973.Tatinclaux, J. C., ‘ ‘Equilibrium Thickness of IceJams,” proceedings of ASCE, 103( HY9):959-974,1977.

“River Ice Jam Models. ” proceedings ofIAHR symposium on Ice Problems, Luela, Swe-den, vol. 11:449-460, 1978.Terstriep, M. L., and Stall, J. B., “The IllinoisDrainage Area Simulator, ILLUDAS, ” IllinoisState Water Survey bulletin 58, 1974.Thompson, J. R., “Quantitative Effects of Water-shed Variances on the Rate of Gully Head Ad-vancement, transactions of ASAE, 7(1):54-55,1964.Thomsen, A. G., and Striffler, W. D., “Hydro-graphy Simulation With Spatially DistributedInput, ” presented at the American GeophysicalUnion fall meeting, San Francisco, Calif., 1979.Thornthwaite, C. W., ‘ ‘An Approach Toward aRational Classification of Climate, GeographicalReview, 38(1):55-94, 1948.USDA, Soil Conservation Service, National Engi-neering Handbook, sec. 4, ‘‘Hydrology’ (Wash-ington, D. C.: U.S. Government Printing Office,1972).USDI, Bureau of Reclamation, “Design of SmallD a m s , A Water Resources Technical Publica-tion, sees. 135 to 139 (Washington, D. C.: U.S.Government Printing Office, 1977).

‘‘A Guide to Integrated Plant, Soil andWater ‘Relationships for Drainage of IrrigatedLands, ’ Drainage ManuaZ, Washington, D. C.,1978.Valencia, D., and Schaake, Jr., J. C., “Disaggre-gation Processes in Stochastic Hydrology, ” WaterResources Research, 9(3):580-585, 1973.Van Haveren, B. P., and Leaveslen, G. H., “Hy-drologic Modeling of Coal Lands, ’ Departmentof Interior, Bureau of Land Management, Denver,Colo., 1979.

113.

114,

115,

116,

117<

118.

119.

120.

Wake, A., and Rumer, R. R., “Development ofa Thermodynamic Model for Ice Regime in LakeE r i e , proceedings of IAHR Symposium on IceProblems, Luela, Sweden, vol. II: 143-162, 1978.Walker, W. R., ‘‘Identification and Initial Evalua-tion of Irrigation Return Flow Models, ” Irriga-tion Hydrology Co., Fort Collins, Colo., 1978.Watt, W. E., “A Relation Between Peak Dis-charge and Maximum 24-Hour Flow for RainfallFloods, Journal of Hychdology, 14:285-292, 1971.Williams, J. R., and LaSeur, W. V., ‘‘WaterYield Model Using SCS Curve Numbers, ” pro-ceedings of ASCE, 102( HY9): 1241-1254, 1976.Wilson, T. V., and Ligon, J. T., “Prediction ofBaseflow for Piedmont Watersheds, ” technical re-port 80, Clemson University Water Resources Re-search Institute, 1979.Woodward, D. E., “Hydrologic and WatershedModeling for Watershed Planning, ” transactionsof ASAE, 99(3):582-584, 1973.World Meteorological Organization, ‘‘Intercom-parison of Conceptual Models Used in OperationalHydrological Forecasting, ” WMO No. 429,Geneva, 1975.Yen, B. C., and Pansic, N., “Surcharge of SewerSystems, Illinois Water Resources ‘Center re-search report 149, 1980.

Surface Water Quality Model References

The following tables and figures are from:D. J. Basta and B. T. Bower (eds. ), Analysis for

Regional Residuals— Environmental QualityManagement: AnaJyzing Natural Systems,Resources for the Future Research Paper(Baltimore, Md.: Johns Hopkins University Pressfor Resources for the Future, 1982).

Figure D-1 displays 14 of the most widely used sur-face water runoff models, and the types of problems eachmodel is capable of analyzing. The following table (tableD-1) lists and identifies the originator of over 40 sur-face water runoff models, including the 14 from figureD-1. Table D-1 is organized by the following categories:screening procedures, simplified computer models, con-tinuous simulation models, and single event simulationmodels. The table includes those models that havereceived most extensive use (both private and govern-mental models) and less widely used models developedby governmental agencies.

Figure D-2 displays 27 of the most widely used receiv-ing water quality models and the types of water bodiesand problems they address. Again, table D-2 followswith a more extensive list of models, concentrating onthose most widely used and/or developed by a Govern-ment agency.

App. D—Additional References to Models and Modeling Studies . 207

● 0 0 ● a ● , ●

“ 0 0 ●

● ● ● 0 ● 0● ● O ●

●

● ● ● 0 ● 0● o e a ● ●

m ● ● m o a e o e e e a● o e e e o ● 0 0

I

● ● 0 ● ● 0 0

● 9


TABLE D-1Commonly Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

SCREENING PROCEDURES

Hydroscience Simplified Model

Storm Water Management Model,Level I

Midwest Research InstituteLoading Functions

SIMPLIFIED COMPUTER

Rational Method

Los Angeles Hydrography Method

Santa Barbara Urban HydrographyMethod

--- Hydroscience, Inc.,Westwood, N.J.

SWMM-Level I Dept. of EnvironmentalEngineering Science,University of Florida,Gainesville, Florida

MM

-—

---

SBUH

Environmental Pollution Assessment- EPARRBErosion, Sedimentation and RuralRunoff Model

TVA Stormwater Model

Midwest Research Institute,Kansas City, Missouri

---

City of Los Angeles,Los Angeles, California

Santa Barbara County FloodControl and WaterConservation District,Santa Barbara, California

National Environmental ResearchCenter, EnvironmentalProtectIon Agency, Athens,Georgia

Division of Water ControlPlanning, Tennessee ValleyAuthority, Knoxville,Tennessee

Simplified Storm Water Managemnt Simplified SWMM Metcalf and Eddy, Inc.,Model Palo Alto, California

CONTINUOUS SIMULATION

Stanford Watershed Model Variants

Stanford Watershed Model IV SUM-IV Department of Civil Engineering,Stanford University, PaloAlto, California


TABLE D-1 (Continued)Commnlv Used Surface Water Runoff Models


Kentucky Watershed Model KWM University of Kentucky,Lexington, Kentucky

Self-Optimizing, Continuous OPSET University of Kentucky,Hydrologic Simulation Model Lexington, Kentucky

National Weather Service River NWSRFS Office of Hydrology, NationalForecast System Weather Service, Silver

Spring, Maryland

Sacramento Model

TVA Daily Flow Model

Hydrocomp Simulation Program

Pesticide Transport and RunoffModel

Agricultural Runoff ManagementModel

Nonpoint Source Model

Terrestrial Ecosystem HydrologyModel

Other Continuous Simulation Models

Agricultural Chemical TransportModel

Streamflow Synthesis and ReservoirRegulation

---

TVA

HSP

Pm

ARM

NPS

TEHM

ACTMO

SSARR

National Weather Service RiverForecast Center and State ofCalifornia Dept. of WaterResources, Sacramento,California

Division of Water ControlPlanning, Tennessee ValleyAuthority, Knoxville,Tennessee

Hydrocomp, Inc.,Palo Alto, California




Oak Ridge National Laboratory,Oak Ridge, Tennessee

Agricultural Research Service,USDA, Beltsville, Maryland

North Pacific Division, Corpsof Engineers, Portland,Oregon


TABLE D-1 (Continued)Commnlv Used Surface Water Runoff Models


Conversational Streamflow Synthesis COSSARR North Pacific Division, Corpsand Reservoir Regulation Program of Engineers, Portland,

Oregon

Storage, Treatnusnt, Overflow, and STORM Hydrologic Engineering Center,Runoff Model Corps of Engineers, Davis,

California

Quantity-Quality-Simulation Model QQS Dorsch Consult, Munich, Germanyand Toronto, Ontario

MIT Catchment Model MITCAT Dept. of Civil Engineering,Massachusetts Institute ofTechnology, Cambridge,Massachusetts and ResourceAnalysis, Inc., Waltham,Massachusetts

SINGLE EVENT SIMULATION

U.S. Dept. of Agriculture USDAHL-74Hydrological Laboratory Model

Problem Oriented Computer Language HYMofor Hydrologic Modeling

Computer Program for Project TR-20Formulation Hydrology

Urban Hydrology for Small TR-55Watersheds

Agricultural Runoff Model AGRUN

U.S. Geological Survey Rainfall USGSRunoff Model for Peak FlowSynthesis

Calcul des Reseaux D’assainissement CAREDAS(Calculation of Sewage Networks)

Agricultural Research Service,USDA, Beltsville, Maryland

Agricultural Research Service,USDA, Soil and WaterConservation ResearchDivision, Riesel, Texas

C-E-I-R, Inc., for SoilConservation Service, USDA,Washington, D. C.

Soil Conservation Service,USDA, Washington, D. C.

Water Resources Engineers, Inc.Walnut Creek, California

U.S. Geological Survey,Reston, Virginia

SOGREAH, Grenoble, France(also New York, New York)


TABLE D-1 (Continued)Commonly Used Surf ace Water Runoff Models


Chicago Hydrography Method City of Chicago Bureau of(also NERO) Engineering, Chicago,

Illinois

Chicago Flow Simulation Program FSP Metropolitan Sanitary Districtof Greater Chicago, Chicago,Illinois

HEC-1 Flood Hydrography Package

Hydrography Volume Method

Illinois Urban Drainage AreaSimulator

Road Research Laboratory Model

Storm Water Management Model

University of Cincinnati UrbanRunoff Model

HEC-1

HVM

ILLUDAS

RRL

UCUR

Hydrologic Engineering Center,Corps of Engineers, DavisCalifornia

Dorsch Consult, Munich, Germanyand Toronto, Ontario

Illinois State Water Survey,Urbana, Illinois

Transport and Road ResearchLaboratory, London, UnitedKingdom

Metcalf and Eddy, Palo Alto,California; University ofFlorida, Gainesville,Florida; Water ResourcesEngineers, Walnut Creek,California

Dept. of Civil Engineering,University of Cincinnati,Cincinnati, Ohio

212 . Use of Mode/s for Water Resources Management, Planning, and Policy

E

$ d

!j ● 3a

.m—

● 00 ● ● ● 0 0 0 ● 0 0 0 0 0 , gS W

. :● 0 0 0 0 ● 0 0 ● 0 0 0 ● 000 ● {

—35-

Z *

; ~

● 0 0 ● 0 ● 0

=* ● 0 0 0 0 ● 0 u

-

3b = ● 0 0 0 ● 0 0 0 0 0 0 g

● 0 0 0 ● 0 0 0 0 0 0 ;

—~

● 00 ● 0 ● 0 0 ● 00 ● ● 000 ● 0 :

● 0 0 0 0 0 0 00

● 0 0 ● 00 ● 0 ● 000 ● 0 :m

● 0 0 0 0 0 0 0 ● 0 0 ● 00 ● ● 00, ● 0 :4 0

mm

— ● L● o .wk. ● 0 0 ● 0 ● :zi

e

<u

( a

● ● :

—~

% ● 0 0 0 0 ● 00 ● ● ● 0 ● 0

: ● ● ●

~ ● ● ●—

!?● 0 0 0 ● ● 0

● 0 ● ● 0 ● 0 ●z.g ● 0 ● ● ● 0 ● 0 ● *

$ ● ● ● 0 ● ●

● ● 0 0 0 ● ● 0—

● 0 0 0 0 ● 0 ● ● 0 ●2’*w ● 0 0 0 0 0 ● 0 0 ● ● 00 ● 0

ii ● 0 0 0 0 0 0 0 0 0 0 ● 0 0 0 0 ● ● 0 0 0 0 ● 0

: ● ● 0 ● ●4z ● 0 0 0 0 ● 0 0 0 ● 0 ●

● ● 0 0 0 0 ● ● ● 0

● 0 0 0 0 ● 0 0 0 0 0 ● 0 0 ● ●

● 0 0 0 0 0 ● ● ●.

i

App. D—Additional References to Models and Modeling Studies 213

TABLE D-2Commonly Used Receiving Water Quality Models

Model Name Commonly Used Acronym O r i g i n a t o r

CHEMICAL REACT ION MODELS

AnalyticallyIntegrated

Streeter-Phelps DissolvedOxygen Equation

Lumped Parameter NutrientBudget Model

I n d i a n a S t a t e B o a r d o f H e a l t h ,B looming ton , Ind i ana

C e n t e r f o r I n l a n d W a t e r s ,Canad ian F i she r i e s Resea rchBoard, B u r l i n g t o n , O n t a r i o

Long Term Phosphorus BalanceModel

S teady-S ta t e S t r eam Ne tworkModel

S imp l i f i ed S t r eam Mode l

S i m p l i f i e d E s t u a r y M o d e l

Numerically Integrated

Dissolved Oxygen Sag Model

Dissolved Oxygen Sag Model(revised version)

SCI DOSAG Modification

Estuary Model

Automatic Quality Model

SNSIM

SSM

SEM

DOSAG-I

DOSAG-3

DOSCI

Esool

AUTO-QUAL

Battelle Pacific NorthwestLabs, Richland, Washington

U.S . Env i ronmen ta l P ro t ec t ionAgency-Region II , New York,New York

Hydroscience, Inc.,Westwood, New Jersey

Hydroscience, Inc.,Westwood, New Jersey

Texas Water Development Board,Austin, Texas

Water Resources Engineers,Austin, Texas

Systems Control Inc.,Palo Alto, California

U.S. Environmental ProtectionAgency-Region II , New York,New York

U.S. Environmental ProtectionAgency, Washington, D. C.


TABLE D-2 (Continued)Commonly Used Receiving Water Quality Models


River Quality Model QUAL-I Texas Water Development Board,Austin, Texas

Dynamic Estuary Model DEM Water Resources Engineers,Walnut Creek, California

Tidal Temperature Model TTM U.S. Environmental ProtectionAgency, Pacific NorthwestLaboratory, Corvallis, Oregon

Receiving Water Model RECEIVModule of SWMM

Receiving Water Model RIVSCI(modification)

Receiving Water Model WRECEV(modification)

Deep Reservoir Model DRM

Lake Ecologic Model LAKSCI(modification of DeepReservoir Model)

Reservoir Water Quality Model EPARES

Hydrocomp Hydrologic Simulation HSPProgram

Water Quality Feedback Model(HA~3 modification)

FEDBAK03

Coastal Circulation and CAFE/DISPERDispersion Model

Estuary Water Quality Model EXPLORE-I

Nutrient Accumulation Model SPLOTCH

Two-Diunsional Stream Mixing ---Model

Water Resources Engineers,Walnut Creek, California

Systems Control, Inc.,Palo Alto, California



Systems Control, Inc.,Palo Alto, California



U.S. Environmental ProtectionAgency-Region II, New York,New York

Ralph M. Parsons Laboratory,Massachusetts Institute ofTechnology, Cambridge,Massachusetts


U.S. Environmental ProtectionAgency, Rochester, New York

Water Resources Division, U.S.Geological Survey,Washington, D. C.


TABLE D-2 (Continued)Commnly Used Receiving Water Quality Models


Outfall Plume Model PLUME U.S. Environmental ProtectionAgency, Pacific NorthwestLaboratory, Corvallis, Oregon

Willamette River Model WIRQAS Water Resources Division, U.S.Geological Survey,Washington, D. C.

HYD/SALEstuary Hydrodynamic/Salinity Model

ECOLOGIC MODELS(All Numerically Integrated)

River Quality Model QUAL-11(QUAL-I modification)

Lake Ecologic Model LAKECO(DRM modification)

Estuary Ecologic 140del ECOMOI)

Estuarine Aquatic Ecologic ESTECOModel

Lake Phytoplankton Model LAKE-1

Eutrophic Lake Quality Model ---

Lake Ecologic Model CLEAN<LEANER

Water Quality in River-Reservoir Systems

WQRRS

Narragansett Bay Hydrodynamic ---

Model

Texas Water Developnwnt Board,Austin, Texas



U.S. Environmental ProtectionAgency, Washington D. C.

Texas Water Development Board/Water Resources Engineers,Austin, Texas

Department of Civil EngineeringManhattan College, New York,New York


International Biological Program,Rensselaer PolytechnicInstitute, New York

U.S. Army Corps of Engineers,Hydrologic EngineeringCenter, Davis, California

Department of OceanEngineering, University ofRhode Island, Narragansett,Rhode Island

Appendix E

Tables of Responses to OTA Survey ofActual and Potential State-Level Model Use

OTA surveyed State agency employees in June, 1980 to determine their current use of modelsand their perceptions of potential model use; data from Part I of this survey are tabulated in thefollowing pages. The respondents were asked to indicate their use of models in 33 water resourceissue areas (left-hand column) for three categories of use (across the top of the tables): A) opera-tions and management, B) planning and policy, and C) other. In these tables, the letter ‘X’represents some model use, and ‘O’ indicates extensive model use. The fourth category at thetop of the tables, labelled ‘N, reports instances in which State agency personnel specifically indi-cated that models are not used, or that no potential for model use exists.

216

App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 217

ALABAMA ALASkA ARIZONA

Exist ing Potential Existing Potential Existing Potential

A B C N A B C N A B C N A B C N A B C N A B C N

1. Flood Forecast. x x x x x x2. Drought/L.Flow x x x x x x x x

3. Streamflow Reg. X X x x x x x x

4 . Instream Flow x x x x x x x x

5. Dem. Water S. x x x x x x x x

6, 1rr. Agri . x x x x x

7. Offatream Use x x x x x x x x

8 . W. Use Effic. x x x x x x x

9. Urban Runoff x x x x x x x x

10. Erosion/Seal. x x x x x x x x

11. Sal inity x x x x x x

12. Agrlc. Runoff x x x x x x x x

13. Airborne Poll. x x x x x x

14 . Waste L . A l l o c . O o x O o x x x x x

15. Thermal Poll. x x x x x

16. Toxic Materials x x x x x x x

17. Drink.Water Qual. x x x x x x

18. W.Q. Impacts x x x x x x x

19. G.W. Supplie8 x x x x x x x x

20. Conjunct. Use x x x x o x x

21. Accid. Contain. x x x x x x x x

22, Ag . Pol l . -gow. x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x24. Salt W. Intrus . x x x x x x x x

25. Water Pricing x x “ x x

26. Costs /Pol l .Con. x x x x

27. Benefit/Cost x x x x

28. Dev. Impllcst. x x x x29. Forecast. Use x x x x x x

30. Social I m p . x x x x31. R i s k / B e n e f i t x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. x x x x x x x

84-589 D - 82 - Is


ARKANSAS CALIFORNIA CDLORADOExist ing Potential Existing Potential Existing Potential—A B C N A B C N A B C N A B C N A B C l ! l A B C N

10 Flood Forecast. x x O x x x x

2 . Drought/L.Flow x x x x x x x x

3. Streamflow Reg, 0 0 0 0 x x

4. Instream Flow o x 00 x x5. Dem. Water S. 0 0 x x x x

60 I r r . Agr lo 0 0 x x x x

7. Offstream Use x x x x x

8e W. Use Efflc. 0 0 x x x x

9. Urban Runoff x x x x x


1 10 S a l i n i t y x X o x x x

12. Agric . Runoff x x x x x x

13. Airborne Poll. x x x x

1 4 . W a s t e L . A l l o c . X X x x x x x x x x

15. Thermal Poll. x x x x

16. Toxic Materials x x x x x x

17. Drink.Water Qual. x x x x x x x x

18. W.Q. Impacts x x x x x x x x

19. G.W. Supplies x x x x x x o 0

20. Conjunct. Use x x x x x x o 0

21. Accid. Contain. x x x x x

22, Ag ● P o l l . - g . w . x x x x x x

23. W. Disposal-g.w. x x x x x x

24. Salt W. Intrus. xx x x x x x25, Water Pricing x x x x x

26. Costs/Poll.Con. x x x x

27. Benefit/Cost x x x x x

28. Dev. Implicat. x x x x

29. Forecast. Use x x x x x

30. Social Imp, x x x x31. R i s k / B e n e f i t x x x x x


33. Unified R.B.M. x x 0 0 x x


CONNECTICUT DELAWARE FLORIDA

Existing Potential Exist ing Potential Existing Potential


10 Flood Forecast. XX xx x x x x

2. Drought/L.Flow x X o x O x x x x x

3. Streamf l ow Reg . X x x x 0 0 x x

4. 1nstream Flow x x x x x x x

5* D e m . W a t e r S . x x x x x x x x x

6. Irr. Agri. x x x x x

7. Offstream Use x x x x x x

8e W. Use Effic. x x x x x

9. Urban Runoff x x x x x x x x x

10. Erosion/Seal. x x x x x xx11. Sal inity o x x x x x x

12. Agric. Runoff x x x x x x x

13. Airborne Poll. x x x x x x x x

14 . Waste L . A l l o c . O o x o x x x

15. Thermal Poll. X x o x x x

16. Toxic Materials x X o x x xx x x

1 7 . D r i n k . W a t e r Q u a l . X x x x x x

18. W.Q. I m p a c t s x x X o x x x x

19. G.W. Supplies x O o x x x x x x x

20. Conjunct. Use x O o x x x x x x

21. Accid. Contain. x x x x x x x x x

22. Ag. Pol l . -g .w. x x x x x x

23. W. Disposal-g.w. X x x x x x x x x x

24. Salt W. Intros. x x x x x x x x x

25. Water Pricing x x x x x x x

26. Costs/Poll. co. x x x x

27. Benefit/Cost x x x x x x x

28. Dev. Impli=t. x x x x x x x

29. Forecast. Use x x x x x x

30. Social Imp. x x x x x x

31. R i s k / B e n e f i t x xx x xx32. Comp. W. Use x x x x x x x

33. Unlfled R.B.M. x x x x x x x


GEORGIA HAWAI1 IDAHO

Exi.sting Potential Existing Potential Existing Potential


1. Flood Forecast. x x x x x x

2. Drought/L.Flow x x x x x x x

3. Streamflow Reg. x x x x x x x

4 . Instream Flow x x x x x x


60 I r r . Agr l . x x x x x

7. Offstream Use x x x x x

8. W. Use Effic. x x x x x x x

9. Urban Runoff x x x x x x x

10. Erosion/Seal. x x x x x x x

1 10 S a l i n i t v x x x x x x x

12. Agric. Runoff x x x x x x x x

13. Airborne Poll. x x x 0 0 0 0

1 4 . W a s t e L . A l l o c . 0 0 00 x x x o x x x

15. Thermal Poll. x x x x x x

16. Toxic Materials x x x x x x x x

17. Drink.Water Qual. x x x x x x x

18. WeQ . Impacts x x x x x x x x

19. G.w. Supplies o x x x x x x x x

20. Conjunct. Use x x x x x x x


22. Age Pol l . -g .w. x x x x x x x x

23. W. Msposal-g.w. x x x x x x x x

24. Salt W. Intrus. x x x x x x x

25. Water Pricimz x x x x x x

26. Costs /Pol l .Con. x x x x x x x x

27. Benefit/Cost x x x x x x x x

28. Dev. Im~licat. x x x x x

29. Forecast. Use x x x x x x x x


31. Risk/Benefit x x x x x x x x

32. Comp. W. Use x x x x x x x x

33. Unified R.B.M. 0 0 0 0 x x x x x x

App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 221

ILLINOIS INDIANA IOWA

Existing Potential Existing Potential Existing Potential


1. F l o o d F o r e c a s t . X X x x O o x O o x X o x

2. Drought /L. Flow x x x x x x x x x x x x

3. S t r e a m f l o w R e g . X X x x x x x x x

4. Inatream Flow x x x x x x x x

5. Dem. Water S. x x x x x x x x x x

6. I r r . Agr i . x x x x x x x

7. Offstream Use x x x x x x x

8. W. Use Effic. x x x x x x x x x x

9. Urban Runoff x x x x x x


11. Sal inity x x x x x x

12. Agric. Runoff x x x x x

13. Airborne Poll. x x x x x

1 4 . W a s t e L . A l l o c . X x x 0 0 o x x

15. Thermal Poll. x x x x x

16. Toxic Materials x x x x x

17. Drink.Water Qual. x x x x x

18. W.Q. Impacts x x x x x

19. G.W. Supplies x x x x x x x x

20. Conjunct. Use x x x x x x x x x

21. Accid. Contain. x x x x x x x

22, Ag . Pol l . -g .w. x x x x x x x


24. Salt W. Intrus. X x x x

25. Water Pricing x x x x x x

26. Costs/Poll.Con. x x x

27. Benefit/Cost x x x x x

28. Dev. Implicat. x x x x x

29. Forecast. Use x x x x x x x

30. Social Imp. x x x

31. Risk/Benefit x x x x


33. Unified R.B.M. x x x x x x

222 ● Use of-Models for Water Resources Management, Planning, and Policy

KANSAS KENTUCKY LOUISIANA

Existing Potent Ial Existing Potent ial Existing Potential


1. Flood Forecast. x x x x x x o x x x

2. Drought/L.Flow x x x x x X o x x x x x x

3. Streamflow Reg. X X x x x x x o 0

4. Instream Flow x x x x x x x x x x

5. Dem. Water S. x x x x x x x x x x x x

6- Irr. Agri . x x x x x x x x x

7. Offstream Use x x x x x x x x x x x

8. W. Use Effic. x x x x x x x x x x

9. Urban Runoff x x x x x x x x x x

10. Erosion/Seal. x x x x x x 0 0 0 x x x

11. Salinity x x x x x x x x x x x

1 2 . Agric. Runoff x x x x x x x x x x

13. Airborne Poll. x x x x x x x x x x

1 4 . W a s t e L . A l l o c . X x x x x x x x o x x x

1 50 Thermal Poll. x x x x x x x x x

16. Toxic Materials x x x 0 0 0 x x x x

17. Drink.Water Qual. x x x 0 0 0 x x x x

18. W.Q . Impacts x x x x 0 0 0 x x x x

19. G.W. Supplies x x x x x x x x 0 0 0 x x 0 0

20. Conjunct. Use x x x x x x x x x x 0 0


22. Ago Poll.-g.w. x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x


25. Water Pricing x x x x x x x x x

26. Costs/Poll.Con. x x x x x x x x x

27. Benefit/Cost x x x x x x x x

28. Dev. Implicat. x x x x x x

29. Forecast. Use x x x x x x x x x

30. Social Imp. x x x x x

31. Risk/Benefit x x x x x x

32. Comp. W. Use x x x x x x x x x

33. Unified R.B.M. x x x x x x x x x x


MAINE MARYLAND MASSACHUSETTS

Exist ing Potential Existing Potential Existing Potential


10 Flood Forecast. XX x x x x x x x x

2. Drought/L.Flow x x x x x x

3. Streamflow Reg. XX x x x

4. Instream Flow x x x x x x

5. Dem. Water S. x x x x x

6. 1rr. Agrl. x x x x xI

7. Offstream Use x x x x


9. Urban Runoff x x x x x x x x x

iO. Erosion/Seal. x x x x x x x x x

11. Salinity x x x x x x x x x x

12. Agric. Runoff x x x x x x x x x x

13. Airborne Poll. x x x x x x x x x

14. Waste L. Alloc. x x x x x x x x x x x

15. Thermal Poll. x x x x x x x x

16. Toxic Materials x x x x x x x x

17. Drink.Water Qual. X X x x x x x x x

18. W.Q. Impacts x x x x x x x x x

19. G.W. Supplies x x x x x x x x x x

20. Conjunct. Use x x x x x x x x


22. Ag. Poll.-g.w. x x x x x x x x x




26. Costs/Poll.Con. x x x x x x


28. Dev. Implicat. x x x x x x



31. Msk/Benefit x x x x x x x

32. ComD. W. Use x x x x x x x


MICHIGAN MINNESOTA MISSISSIPPI



1. Flood Forecast. x x x x x x x x

2 . Drought/L.Flow x x x x x x x x

3. Streamflow Reg. x x x x x x x x

4. Instream Flow x x x x x x x x x

5* Dem. Water S. x x x x x x x

6. Irr. Agri. x x x x x x x x

7. Offstream Use x x x x x x x


9. Urban Rmoff x x x x x x x x x x x

10. Erosion/Sed. x x x x x x x x x x x

11. Sal inity x x x x x x x

12. Agric. Rtmoff x x x x x x x x x x

13. Airborne poll. x x x x x x x x x x

14. Waste L. Alloc. x x x o x x x x X o x x

15. Thermal Poll. x x x x x x x x x x x

16. Toxic Materials x x x x x x x x x x x

17. Drink.Water Qual. x x x x x x x x x

18. W.Q. Impacts x x x x x x x x x x x

19. G.W. Supplies x x x x x x x x x x

20. Conjunct. Use x x x x x x x x x x

21. Accid. Contain. x x x x x x x x x x x

22. Ago Poll.-g.w. x x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x x

24. Salt W. Intrus. x x x x x x


26. Costs/Poll.Con. x x x x x x x


28. Dev. Impliat. x x x x x x x

29. Forecast. Use x x x x x x


31. Risk/Benefit x x x x x x


33. Unified R.B.M. x x x x x x x x


MISSOURI MONTANA NEBKASKA



1. Flood Forecast. x x x x o x o x x x

2. Drought/L. Flow x x x x o

3. Streamflow Reg. x x x x o x x

4. Instream Flow x )$ x x x x x x

5. Dem. Water S. x x x x x x


7. Off stream Use x x x x x


9. Urban Runoff x x x x

10. Erosion/Seal. x x x x x

11. Salinity x x x x


13. Airborme Poll. x x x x x x x x x x x

1 4 . W a s t e L . A l l o c . x x x x

1 5 . T h e r m a l P o l l . x x x x

1 6 . T o x i c M a t e r i a l s x x x x17. Drink. Water @al. x x x x x x

18. W .Q. Impacts x x x x x x x

19. G.W. Supplies x x x x x x 0 0 X o

20. Conjunct. Use x x x x x x o x x x

21. Accld. Contain. x x x x x x

22. Ag . Poll. -g. w. x x x x x x x x x x

23. W. Disposal-g .w. x x x x

24. Salt W. Intrus. x x x x x


26. Costs /Poll .Con. x x x x x

27. Benefit/Cost x x x x

28. Dev. Impli=t. x x x x x

29. Forecast. Use x x x x

30. Social imp. x x x x x x x

31. Risk/Benefit x x

32. CoIQp. W. Use x x x

33. Unified R.B.M. x x x x

226 Use of Models for Water Resources Management, Planning, and policy

NEVADA NEW HAMPSHIRE NEW JERSEY



10 Flood Fore-st. XO x x

2. Drought/L.Flow x x X o

3 . Streamflow Reg. X X o

4 . Instream Flow X o o


6. Irr. Agri. x x x

7. Offstream Use x x x

8. W. Use Effic. x x x x x

9. Urban R-off x x x x x

10. Erosion/Seal. x x x x x x

11. Salinity x x x x x x x x x x



14. Waste L. Alloc. O 0 x x x x x x x x

1 50 Thermal Poll. X o x x x x

16. Toxic Materials XX x x x x x x

17. Drink.Water Qual. X x x x x x x

18. W.Q. Impacts 0 0 x x x x x

19. G.W. Supplies x x x x x x x


21. Accid. Contain. x x x x x x

22. Ago Poll.-g.w. x x x x x


24. Salt W. Intrus. x x x x

25. Water Pricing x x x x x x x x

26. Costs/Poll.Con. x x

27. Benefit/Cost X o x

28. Dev. Impli@t. X x x

29. Forecast. Use x x x

30. Social Imp. x x


32. Comp. W. Use x x x x x

33. Unified R.B.M. x x x x x

App. E— Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 227—.————.-——.——— —.—

NEW MEXICO NEW YORK NORTH CAROLINA



10 Flood Forecast. X x x x x x x x x

2. Drought /L. Flow x x x X o x x x x

3* Streamflow Reg. X x x o x x x x x

4. Instream Flow x x o x x x x x


6. 1rr. Agri. x x x x x x x x x

7. Off stream Use x x x x x x x x

8. W. Use Effic. x x x x x x x x x

9. Urban Runoff x x x x x x x x

10. Erosion/Seal. x x x x x x x

11. Sal lnity x x x x x


13. Airborne Poll. x x x x x x x x x

14. Waste L. Alloc. X X x x x x o x x x

15. Thermal Poll. x x x x x x x x

1 6 . T o x i c M a t e r i a l s X X x x x x x x

1 7 . D r i n k . W a t e r O u a l . x x x x x x x

18. W.Q. Impacts x x x x x x x x x x x x

19. G.W. Supplies o x x x o x x x x

20. Conjunct. Use o x x x x x x x x

2 1 . A c c i d . C o n t a i n . x x x x x x x

22. Ags poll.-~.ti. x x x x x x

23. W. Disposal-g. w. x x x x x

24. Salt W. Intrus. XX x x x x x x


26. Costs /Poll .Con. x x x x x x x x

27. Benefit/Cost x x x o x x x x x x

28. Dev. Implicat. x x x x x x x x x

29. Forecast. Use x x x x x x x x

30. Social Imp. x x x x x x x x

31. Risk/Benefit x x x x x x x x


33. Unified R.B.M. x x o x x x x x


NORTH DAKOTA OHIO OKLAHOMA



1. Flood Forecast. x x 0 0 0 0 x x x

2 . Drought /L. Flow x x x 0 0 0 0 x x x

3 . Streamflow Reg. X o x 0 0 0 0 x x x

4. Inatream Flow x x x x x x x x x

5. Dem. Water S. x x x x x x x x x


7. Off stream Use x x x x x x x x x

8. W. Use Effic. x x x x x x x x x

9* Urban Runoff x x 0 0 x x x

10. Erosion/Seal. x x x x x x

110 Salinity x x x x x

12. Agric. Runoff x x x x x x

13. Airborne Poll. 0 0 0 0 x x x

14. Waste L. Alloc. 0 0 0 0 x x x

15. Thermal Poll. 0 0 0 0 x x x

16. Toxic Materials x 0 0 x x x

17. Drink.Water @al. x x x x x x

18. W.Q. Impacts 0 0 0 0 x x x

19. G.W. Supplies o x x x 0 0 0 0 x x x x x

20. Conjunct. Use x x x x x x x x x x


22. Ag. Poll.-g.w. x x x x x


24. Salt W. Intros. x x x x x x



27. Benefit/Cost x x x x x x

28. Dev. Impllmt. x x x x x x x

29. Forecast. Use o x x x x

30. Social Imp. X o x x x x x x

3 1 . R i s k / B e n e f i t x x x x x

32. Comp. W. Use x x x x


App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 229

1. Flood Forecast.

OREGON PENNSYLVANIA RHODE ISLAND



x x x x x x x x x x

2* Drought /L .Flow x x x x x x x X o

30 Streamflow Reg. x x x o x x x x

4. Instream Flow x x x x x x x x


6. 1rr. Agrl. x x x x x x x

7. Off stream Use x x x x x x x

8. W. Use Effic. x x x x x x

9. Urban Runoff x x x x x x


11. Salinity x x x x x



14. Waste L. Alloc. o x x x x x x x

1 5 . T h e r m a l P o l l . o x x x x x x

16. Toxic Materials 0 0 x x x x

1 7 . D r i n k . W a t e r Q u a l . 0 0 x x x x

1 8 . W . Q . I m p a c t s 0 0 x x x x x

19. G.W. Supplles x x x x x x 0 0

20. Conjunct. Use x x x x x 0 0


22. Age Poll.-g.we x x x x x

23. W. Disposal-g.w. x x x x x x x

24. Salt W. Intrus. x x x x x

25. Water Pricing x x


27. Benefit/Cost x o x x x x x

28. Dev. Implimt. x x x x x

29. Forecast. Use x x x x x

30. Social Imp. x x x x x

31. Risk/Benefit x x x x x x x


33. Unified R.B.M. x o x x 0 0


SOUTH CAROLINA SOUTH DAKOTA TENNESSEE



1. Flood Forecast. x x x x

2. Drought/L.Flow x x

3. Streamflow Reg. x x x x x

4. Instream Flow x x

5. Dem. Water S. x x

60 Irr. Agri. x x

7. Offstream Use x x

8. W. Use Effic. x x

90 Urban Runoff x x x x x

10. Erosion/Seal. x x x x x x x x x x

11. Salinity x x x x x x


13. Airborne Poll. x x x

14. Waste L. Alloc. O 0 x x x x o 0

15. Thermal Poll. x x x o

16. Toxic Materials X x x x

17. Drink.Water Qual. X x x x x x

18. W.Q . Impacts x x x x x x x

19. G.W. Supplies x x x o x x x



22. Ago Poll.-g.w. x x x x x x




26. Costs/Poll.Con. x x

27. Benefit/Cost x x x

28. Dev. Implicat. x x

29. Forecast. Use x x

30. Social Imp. x x


32. Comp. W. Use x x x x x

33. Unified R.B.M. x x x


TEXAS UTAH VERMONT


A B C N A B C N ABC Ii A B C N A B C N A B C N

1. F l o o d F o r e c a s t . 0 0 x x x x x x x x x

2. Drought/L.Flow x x x x x x x x x

3. Streamflow Reg. x x x x x x x x x x x

4. Instream Flow 0 0 x x x x x x x x x

5. Dem. Water S. x x x x x x x x x x

6. Irr. Agri . X o x x x x x x x x x x x

7. Offstream Use o x x x x x x x x x x x

8. W. Use Effic. O o x x x x x x x x x x

9. Urban Runoff o x x x x x x x x x x


11. Salinity x x x x x x x x x

12. Agric. Runoff o x x x x x x x

13. Airborne Poll. x x x x x x x x x x 0 0 0 0

14. Waste L. Alloc. x x x x x x o x 0 0

15. Thermal Poll. X o x x x x x x x x x x x x

16. Toxic Materials O o x x x x x x x x x x

17. Drink.Water Qual. O x x x x x x x x x x

18. W.Q . Impacts x x x x x x x x x x

19. G.W. Supplies X o x x x x x x x x x x x x

20. Conjunct. Use X o x x x x x x x x

21. Accid. Contain. x x x x x x x x x x

22. Ag. Poll.-g.w. x x x x x x x x x


24. Salt W. Intrus. x x x x x x x x x



27. Benefit/Cost o x x x x x x

28. Dev. Implicat. o x x x x x x

29. Forecast. Use o x x x x x x x


31. Risk/Benefit x x x x x x x x32. Comp. W. Use x x x x x x x

33. Unified R.B.M. x x x x x x x

.


VIRGINIA WASHINGTON WEST VIRGINIA



1. Flood Forecast. x x x x X o X o

2* Drought/L.Flow x x x x x X o X o

30 Streamflow Reg. x x x x x x X o X o

4. Instream Flow x X o x x x


6. Irr. Agri. x x x x x

7. Offstream Use x x x

8. W. Use Effic. x x x x

9* Urban Rutoff x x x x x


11. Salinity x

12. Agric. Rmoff x

13. Airborne Poll. x

14. Waste L. Alloc. X o x X o X o

15. Thermal Poll. x X o X o

16. Toxic Materials x x x x x

17. Drink.Water Qual. x

18. W.Q. Impacts x x x X o X o

19. G.W. Supplies O x x x x x

20. Conjunct. Use x x X o x o

21. Accid. Contain. x x

22. Ag. Poll.-g.we x x x

23. W. Disposal-g.w. x x o

24. Salt W. Intrus. x x x

25. Water Pricing x x x

26. Costs/Poll.Con. x

27. Benefit/Coat x x

28. Dev., Impliat. x x

29. Foreumt. Use x x x x

30. Social Imp. x x


32. Comp. W. Use x x


App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 233

WISCONSIN WYOMING WASHINGTON, D.C.



1. Flood Forecast. X X x x x x x x x x

2. Drought/L.Flow x x o x x x x x x x x x

3. Streamflow Reg. x x x x x x x x x x x

4. Instream Flow x o x x x x x x


6. Irr. Agri . x o x x x x x x

7. Offstream Use x o x x x x x x

8. W. Use Effic. x x x x x x x x

9. Urban Runoff x x x x x x x x x x x X o

10. Erosion/Seal. x x x x x x x x x x x x

11. Salinity x x x x x x x

12. Agric. Runoff x x x x x x o x

13. Airborne Poll. x x x x x x x x

14. Waste L . A l l o c . 00 x x x x x x

1 5 . T h e r m a l P o l l . x x x x x x x

16. Toxic Materials x x x x x x

17. Drink.Water Qual. x x x x x x

18. W.Q . Impacts x x x x x x x x x x x

19. G.W. Supplies x x x x x x x

20. Conjunct. Use x x x x x x x x x x x

21. Accid. Contain. x x x x x x x x x x

22. Ag . Poll.-g.w. x x x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x x x



26. Costs/Poll.Con. x x x x x x x x x

27. Benefit/Cost x x x x x x

28. Dev. Implicat. x o x x x x x



31. Risk/Benefit x x x x x x x


33. Unified R.B.M. o x x x x x

Index

Index

Ada, Okla., 168agriculture

as greatest user of water, 31irrigation in, 109, 128-129as a water pollution source, 33

aquatic lifewater quality impacts on, 140-141

Argonne National Laboratory, 177Army Corps of Engineers, 9, 11, 110, 135, 136,

157, 158assistance to States, 99Coastal Engineering Research Center

(CERC), 177drought and low-flow models provided by, 109Engineering Computer Programs Library, 60Hydrologic Engineering Center (HEC), 10, 15,

17, 20, 51, 53, 60, 84-85, 92, 108, 177models used by, 176-177Office of the Chief of Engineers, 60role in water resources, 176thermal pollution modeling services of, 112training programs conducted by, 106, 108Waterways Experiment Station (WES), 177

Athens, Ga., 91

Bay St. Louis, Miss., 86Bureau of Mines, 72

Canadasurvey of environmental management simulation

models in, 201carbon tetrachloride, 140Catalog of Information on Water Data, 81Center for Water Quality Modeling (see

Environmental Protection Agency)Chase Econometrics, Inc.

macroeconomic model of, 157Chesapeake Bay, 183, 186

Kepone in, 136storm surges in, 186

coastal areasindex to stations in, 81

coastal zone management, 85Colorado River Basin, 87Colorado River Basin Salinity Control Program, 70Congress

acts of (see legislation)options available to, 11-12, 13-14, 16, 17-18,

20-21Senate Select Committee on National Water

Resources, 25Connecticut River, 7

Cooperative Instream Flow Service Group (seeInstream Flow Group

Cornell university, 6Corps of Engineers (see Army Corps of Engineers)Council on Environmental Quality (CEQ

models used by, 182

Department of Agriculture (USDA), 111assistance to States, 99drought and low-flow models provided by, 109Economic and Statistics Service (ESS), 172Forest Service, 71, 72, 174Land and Water Conservation Task Force, 92Land and Water Resources and Economic

Modeling System (LAWREMS), 17, 88,92-93, 172

models used by, 172-176Science and Education Administration

(SEA), 174-175Soil Conservation Service (SCS), 75, 78, 108,

135, 136, 157, 172, 175Department of Commerce, 82, 158

models used by, 176-177National Oceanic and Atmospheric

Administration (NOAA), 175-176Department of Energy (DOE)

Federal Energy Regulatory Commission(FERC), 178

Office of Environmental Assessments, 177-178Department of the Interior (DOI), 72, 77, 78

79, 82, 87Bureau of Land Management (BLM), 178Bureau of Mines, 178-179Bureau of Reclamation, 157, 158, 180-181Fish and Wildlife Service, 179models used by, 178-182Office of Surface Mining, 179Office of Water Data Coordination

(OWDC), 80-82Office of Water Research and Technology

(OWRT), 19, 20, 21, 79, 168, 179State Institute Program, 79-80University Water Research Program,

9, 10, 19, 20U.S. Geological Survey (USGS), 181-182

Department of Transportation, 78I.)01, (see Department of the Interior)DRI

macroeconomic model of, 157drought and low stream flow

forecasting of, 109, 126

237


economi c cand c and social issues, 29competitive water use, 116cost/benefit analysis, 115, 157-158costs of pollution control, 114-115, 157effects of pricing on water use, 114, 156-157forecasting water use, 116, 159models for analysis of, 152-161regional economic development, 115-116, 158-159risk/benefit analysis, 116, 159-160social impact, 116unified river basin management, 116, 161

Economic and Statistics Service (see Department ofAgriculture)

Economic Assessment Model, 158energy development, 85environmental impact evaluation, 85Environmental Protection Agency (EPA), 8, 9, 13,

14, 33, 72, 78, 87, 136, 137, 138, 139,157, 168, 172

Center for Water Quality Modeling, 17, 18, 50,88, 91-92

Cleveland Electric Illuminating Co. v. EPA, 62Environmental Research Laboratory, 91, 92Holcomb Groundwater Model Clearinghouse,

14, 18Holcomb Research Institute, 50, 88, 168International Clearinghouse for Groundwater

Models (ICGWM), 17, 88-89models used by, 182-185Office of Research and Development (ORD),

90, 183Office of Toxic Substances (OTS), 184Office of Water Enforcement, 184-185Office of Water Program Operations

(OWPO), 183Office of Water Regulations and Standards

(OWRS), 183Office of Water and Waste Management, 183Stormwater Management Model (SWMM), 15,

20, 50, 89-91, 105, 135thermal pollution modeling services of, 112

Executive Office of the President (EOP), 77Executive Order No. 11988 (see flood plain

management

Federal Council for Science and TechnologyCommittee on Water Resources Research

(COWRR), 77Federal Emergency Management Agency, 71, 108

models used by, 186Federal Insurance Administration (FIA), 186Federal Software Exchange Center (FSEC) (see

General Services AdministrationFish and Wildlife Service, 87, 110Flander’s Bay (Long Island, N.Y. ), 41, 42, 43flood plain management, 85, 109, 176

Executive Order No. 11988, 8, 69, 174, 175floods

assistance to States in control of, 99control of, 4, 30, 108, 124-126damage from, 30, 124distribution of information by Federal

agencies, 108forecasting of, 108, 124-126insurance, 109warning systems for, 85

Forest Service (see Department of Agriculture)

GAO (see General Accounting Office)General Accounting Office (GAO), 60, 61, 73, 74,

75, 84survey on improving management of federally

funded computerized models, 199General Services Administration (GSA)

Federal Property Management Regulations, 83Federal Software Exchange Center (FSEC), 17,

18, 49, 83-84Great Lakes, 183

polychlorinated biphenyls (PCBS) in, 141ground water, 29, 34, 37, 85

availability of, 34, 146-147conjunctive use of surface water and,

113-114, 146model types available for analysis of, 151-152model types used in resource analysis of, 144-146pollution of, 43, 114quality, 147-151quantity and quality of, 143-152saltwater intrusion in, 37-38, 40, 114SCOPE International Assessment Project on

models of, 201as sole source of drinking water in Long Island,

N. Y., 40subsidence caused by withdrawal of, 147supplies and safe yields of, 113

GSA (see General Services Administration)Gulf Coast Hydroscience Center, 86

Holcomb Clearinghouse (see EnvironmentalProtection Agency)

Holcomb Research Institute (see EnvironmentalProtection Agency)

Hudson Riverpolychlorinated biphenyls (PCBS) in, 141

hydroelectric power, 4, 109hydrologic cycle, 121Hydrologic Engineering Center (HEC) (see Army

Corps of Engineers)

Illinois Pollution Control Board, 63Index to Stations in Coastal Areas, 81

Index . 239

Instream Flow Group, 12, 20, 51, 87-88, 110Interagency Advisory Committee on Water

Data, 81International Clearinghouse for Groundwater

Models (ICGWM) (see EnvironmentalProtection Agency)

James River, 183Kepone in, 136, 141

Johnson, Dr. William, 53

Kepone, 136, 141

Lakewood, Colo., 86Land and Water Resources and Economic Modeling

System (see Department of Agriculture)land-use planning, 85legislation

Atomic Energy Act, 8, 70, 186Brooks Act, 83Clean Air Act, 137Clean Water Act, 6, 8, 14, 70, 72, 97, 102, 110,

111, 112, 114, 115, 135, 137, 138, 139, 140,172, 174, 175, 176, 179, 180, 182, 183, 185

Coastal Zone Management Act, 8, 69Colorado River Basin Salinity Act, 175Colorado River Salinity Control Act, 180Endangered Species Act, 8, 69, 174, 180Energy Conservation Standards for New

Buildings Act, 64Federal Insecticide, Fungicide, and Rodenticide

Act, 184Federal Power Act, 178Federal Reclamation Act, 8, 69, 180, 180, 182Federal Water Pollution Control Act, 40, 68,

138, 172Fish and Wildlife Coordination Act, 176, 179Flood Control Act, 8, 69, 174, 175, 176,

178, 180Food and Agriculture Act, 174Forest and Rangeland Renewable Resources

Act, 71Forest and Rangeland Renewable Resources

Planning Act, 174Intergovernmental Personnel Act, 87National Environmental Policy Act, 8, 69, 139,

153, 176, 180National Environmental Protection Act, 61, 186National Flood Insurance Act, 8, 69, 71, 186National Forest Management Act, 71, 174Organic Act, 176Resource Conservation Act (see Soil and Water

Resources Conservation Act)Resource Conservation and Recovery Act, 8, 68,

97, 140, 182

Rural Clean Water Program, 175Safe Drinking Water Act, 8, 14, 68, 72, 97, 140,

179, 182, 183, 184Soil and Water Resource Act, 69Soil and Water Resources Conservation Act, 8,

172, 174, 175, 179, 182Surface Mining Control and Reclamation Act, 8,

69, 174, 179, 182Toxic Substances Control Act, 8, 72, 140, 184Watershed Protection and Flood Prevention Act,

174, 175Water Research and Development Act, 8, 11, 13,

77, 79, 82Water ResourcesWater Resources

115, 172, 175,Water Resources

Long Island, N,Y.

Development Act, 174, 180, 182Planning Act, 8, 69, 97, 114,178, 182, 185Research Act, 79

as-a case study of model use, 40-43Long Island Regional Planning Board, 6

mathematical models (see models)Menlo Park, Calif., 86Model Annotation Retrieval System (MARS), 89models

access to Federal, 106of agricultural runoff, 111, 136-137, 183of agricultural soil/water interaction, 122of airborne pollution, 112, 137-138alluvial process, 123appropriateness of, 170-171aquatic life impact, 112-113of aquifer characteristics, 102Argonne Water Quality Accounting System

(AQUAS), 177Automated Downstream Accounting Model

(ADAM), 177baseflow, 121Bureau of Reclamation Economic Assessment

Model (BREAM), 181calibration of, 56-57channel process, 123characteristics affecting ease of using, 52-53Chemicals, Runoff, and Erosion from

Agricultural Management System(CREAMS), 175

clearinghouse for, 169Colorado River System Simulation (CRSS), 185of competitive water use, 116for conjunctive use of ground and surface water,

113-114constraints to use by States, 104-107of contaminant transport, 144-146coordination of information on, 170coordination mechanisms for, 80-84


in cost/benefit analysis, 115data availability for, 73, 105, 167-168in data management, 29decisionmaker understanding of, 73-74, 170definition of, 26-30descriptive, 28, 29-30deterministic, 30dissemination of, 75documentation of, 107, 168for drinking water quality, 112in drought and low-flow forecasting, 109, 126economic and social, 152-161, 166of erosion and sedimentation, 135-136in erosion and sedimentation studies,

33, 110, 136evaluation of, 55-59Exposure Analysis Modeling System

(EXAMS), 183Federal agency publications on, 187-192Federal agencies using, 172-186Federal approaches to management of, 76-93Federal expenditures on water-related, 4, 9Federal programs using (table), 68-70Federal use and support of water resource

models, 67-93in flood control, 30, 124-126in flood and drought frequency analysis, 124general uses of, 5-8, 25-30in ground water assessment, 34-37, 38-39, 43,

146, 165-166of ground water flow, 144of ground water pollution, 39higher dimension, 167of instream flow, 110of instream needs, 127-128interaction between modelers and decisionmakers,

53-55interagency (Federal) coordination on, 75-76in irrigation, 7, 122issues related to, 10-21, 47-64lack of coordination among agencies using, 9land drainage, 122legal aspects of, 61-64, 171legislation associated with use of, 8in Long Island, N. Y., 41-43Los Alamos Coal Use Modeling System

(LACUMS), 177maintenance of, 52, 75, 107, 169to meet State needs, 104-105Multiple-Objective Programing (MOP), 180National Weather Service River Forecast System

(NWSRFS), 176of offstream water use, 109in operations and management, 29, 43

oversight in development of, 59-61personnel shortage for, 105-106in planning and policy development, 29, 41in pollution control, 39, 112, 114-115potential at the State level, 10predictive, 28prescriptive, 30in the private sector, 167probabilistic (stochastic), 30, 166process, 121of receiving-water quality, 183references to studies of, 187-192, 202-206in regional economic development, 39, 115-116Regional Energy Location Model (RELM), 180in regulation, 29reliability and credibility of, 106-107research and development needs on, 165-167Return Flow Quality Simulation Model, 181in risk/benefit analysis, 39-40, 116of river basins, 27-28, 39, 116for salinity control, 136in social impact assessment, 116standardization of, 107statistical, 121, 123-124State funding of, 107State government use of, 97-116Strategic Environmental Assessment System

(SEAS), 178stream process, 123in streamflow regulation, 31, 59, 109, 126-127support services for, 9, 47-53, 84-93of surface water flow and supply, 165in surface water flow and supply analysis,

121-124of surface water quality, 165of surface water salinity, 111System of Watershed Automated Management

Information (SWAMI), 175of thermal pollution, 112, 139-140of toxic materials, 34, 140training in, 50-51Universal Soil Loss Equation (USLE), 175of urban runoff, 110, 123, 134-135used by Army Corps of Engineers, 176-177used by Council on Environmental Quality, 182used by Department of Energy, 177-178user assistance in, 51-52, 88-93user support of, 74-75validation of, 56, 57-58, 168of wasteload allocation, 8, 33, 112, 138-139Water Assessment System, 177for water budgeting, 41in water conservation, 32in water current studies, 41-42

Index ● 241

in water pricing, 40, 114of water quality, 140in water use forecasting, 40, 116Water Use Information System (WUIS), 177

Nassau-Suffolk Regional Planning Board, 40, 41National Academy of Sciences (NAS), 79

Water Resources Research ReviewCommittee, 78

National Bureau of Standards (NBS), 75study of ways to improve utility of large-scale

models, 200National Commission on Water Quality, 138National Dam Safety Program, 108National Oceanic and Atmospheric Administration

(NC)AA), 108National Pollution Discharge Elimination

System, 63National Research Council, 11National Science Foundation (NSF), 21, 73,

74, 75, 168survey of federally supported mathematical

models, 199water resources research funded by, 185

National Technical Information Service (NTIS), 17,49, 82, 82-83

National Water Data Exchange (NAWDEX), 81-82Nationwide Weather Service (NWS), 6, 7, 176

drought and low-flow models provided by, 109Nationwide Urban Runoff Program, 134-135Nebraska, 7Nuclear Regulatory Commission (NRC), 72, 139

models used by, 186

Occoquan Reservoir (Virginia), 6Office of Management and Budget (OMB), 12, 80Office of Science and Technology Policy (OSTP),

12, 77, 78, 79Office of Technology Assessment (OTA), 5, 9, 10,

11, 13, 16, 49, 50, 53, 67, 70, 73, 74, 75, 79,84, 108

State modeling survey, 97-98Technologies for Determining Cancer Risks From

the Environment, 140workshops on water resource modeling, 165-171

Office of Water Data Coordination (OWDC), 80-82Office of Water Research and Technology (OWRT)

(see Department of the Interior)Ohio River, 140

carbon tetrachloride in, 140OSTP (see Office of Science and

Technology Policy)

Peconic River (Long Island, N.Y. ), 41Pecos River Basin (New Mexico), 6

Pennsylvania, 172pollution

from agricultural runoff, 33, 41, 149-150airborne, 33, 112costs of controlling, 114-115of drinking water by bacteria and viruses, 34of drinking water by toxic chemicals, 33-34effects on aquatic life, 33from erosion, 33of ground water, 39, 43, 147-152in Long Island, N. Y., 40point sources of, 38-141from seawater intrusion, 150-151thermal additions to streams, 33, 72, 112from urban and industrial areas, 147-149from urban storm runoff, 33from waste disposal sites, 150

polychlorinated biphenyls (PCBS), 141President Carter, 77President of the United States, 77

reservoirs, 121as multiple-purpose facilities, 6operations, 109sedimentation in, 136

Resources for the Future, 25Reston, Va., 86

San Joaquin Valley (California), 172Secretary of Interior, 11, 77Smithsonian Scientific Information Exchange

(SSIE), 82social issues (see economic and social issues)

Soil Conservation Service (see Department ofAgriculture)

Stormwater Management Model (SWMM) (seeEnvironmental Protection Agency)

streamflow regulation, 109support services (see models)Supreme Court, 61surface water, 85

agricultural runoff, 111-112, 136-137aquatic life, 112-113availability of, 120-121conjunctive use of ground water and,

113-114, 146drinking water, 112erosion and sedimentation, 110-111, 135-136eutrophication of, 133evaporation of, 122flow and supply of, 29, 108-110, 119-131,

130, 165model types used in quality analysis of, 132-134,

141-143pollution of, 112, 132, 133, 137-138

— .


quality of, 29, 110-113, 131-143, 165salinity of, 111, 136urban runoff, 110, 134-135use of, 121watershed models, 121, 121, 121

Tennessee Valley Authority (TVA), 6-7, 157

University Water Research Program (seeDepartment of the Interior)

U.S. Geological Survey (USGS), 9, 10, 11, 15, 20,51, 82, 84, 108, 110, 111, 113, 135

Federal-State Cooperative Program, 86National Training Center, 86training programs conducted by, 106Water Resources Division, 85-87

wasteload allocationdefinition, 138

waste storage and utilization, 85water (see specific entries, e.g. , surface water,

ground water, water resources)water resources

activities involved in managing, 30conservation of, 32-33, 110, 129demand for professionals in, 9

domestic water supplies, 109-110, 128, 140drought and low stream flow, 30, 109effect of urban storm runoff on, 33Federal expenditures for, 4Federal-State cooperation on, 12-13instream flow needs, 31, 110irrigation, 109issues in, 26, 30-40, 99, 101, 101-102, 102-103,

113-116in Long Island, N. Y., 40-43mathematical models of, 5-8, 26-30, 55-59offstream uses of, 31, 109, 129pollution of, 32, 33, 72, 138-141quality of, 85research on, 11-12, 77, 78-80sedimentation in waterways, 33State research institutes on, 79-80State use of models for, 101streamflow regulation, 31-33, 59, 109

Water Resources Council, 12, 30, 81, 158, 172, 177models used by, 185Principles and Standards of, 153

Water Resources Scientific Information Center(WRSIC), 16, 18, 49, 82

World Meteorological Organization, 59

Us. GOVERNMENT PRINTING OFFICE : 1982 0 - 84-589