Chesapeake Bay Program Watershed Model 101

Chesapeake Bay Program Modeling

Chesapeake Bay ProgramWatershed Model

101


Role of Models

Modeling

Research Monitoring

Management

Power

ClarityWhat is the Concentration?What are the filtering rates?Where are the streams?

What is the environmentaleffect of any particularmanagement scheme?

How do we balance manydifferent interests?


CBP Modeling Structure

Watershed Model

Chesapeake Bay Estuary Model Package

Regional Acid Deposition Model


Topics

• Description of the Watershed Model

• Calibration

• Data

• Use in Management


• CalibrationCalibration

• DataData

• Use in ManagementUse in Management


Purposes of the Watershed Model

1. Accurately deliver loads to the WaterQuality Model

2. Equitably account for all load sources

3. Assess changes due to management


Requirements for WSM

• Daily flow, nutrient, and sediment load• Accurately simulate any major land use• Responsive to

Nutrient input to land Structural BMPs Changes in stream chemistry Meteorology


HSPF• Hourly time step• Heavily parameterized

sensitive to many inputs very flexible

• Open Source, Free• Supported by USGS and EPA• Wide usage


HSPF

Lumped parameterPhysically-based models


HSPF - lumped model


Land Simulation --1 Acre

Ground Water

SurfaceInterflow Lower Zone


Water simulation - physically based

Ground Water

Surface

Interflow

Lower Zone


Precipitation or percolation

Percolation

Evapotranspiration

RO

(time series)

f(soil properties, slope, temp)

f(time series, land properties)

f(soil properties, slope, temp)

Water simulation - physically based


Nutrient and Sediment Simulation

Meteorology Precipitation

Runoff andGroundwater

LandMorphology

NitrogenCycle

SedimentExport

PhosphorusCycle

Nutrient Inputs


Nutrient and Sediment Simulation

NitrogenCycle


Trees

Roots Leaves

ParticulateRefractoryOrganic N

ParticulateLabile

Organic N

SolutionAmmonia

Nitrate

SolutionLabile

Organic N

AdsorbedAmmonia

SolutionRefractoryOrganic N

Nitrogen Cycle in Watershed Model ForestA

tmos

pher

ic

Dep

ositi

onD

enitr

ifica

tion

Export

Export Export ExportExport Export Export


Model Nutrient BalanceAtmosphericDeposition

DenitrificationVolatilization

Export to Streams


Land Uses Modeled

Forest


Model Nutrient BalanceAtmosphericDeposition,

other sources


Export to Streams

Uptake bygrasses


Land Uses Modeled

Pervious Urban, Impervious Urban


Model Nutrient BalanceAtmosphericdeposition,

Manure,

Fertilizer


Export to Streams

Uptake byCrops


Land Uses Modeled

High Till, Low Till, Hay, Pasture


Land-Water Connection

X 3000 acres

X 400 acres

X 900 acres

X 100 acresX 200 acres X 300 acres


River Simulation

River 3


N River Simulation

Algae

ORGN

NO3

}

Sediment

NH3


River Simulation

River 1

River 2 River 3


Watershed Model

• 64,000 square miles• Nine land uses• 94 segments


Topics


• Calibration

• Data


• Description of the Watershed ModelDescription of the Watershed Model

• Calibration

• DataData



2 points of calibration

Land Surface

RainRiver Reach


Calibration• Exports from land

Literature values Analysis of input

• River input to tidal waters Data at all major inputs Upstream points


Figure 12. Crop Nitrogen

0

10

20

30

40

50

60

70

80

Beaulac & Reckhow Sparrow Sweeney & Chang CBP Model

lb/a

c/ye

ar


Figure 13. Crop Phosphorus

0

2

4

6

8

10

12

14

16

18

Beaulac & Reckhow Sweeney & Chang model

lb/a

c/ye

ar


Figure 23. Hay Nitrogen

0

2

4

6

8

10

12

14

16

Beaulac & Reckhow model

lb/a

c/ye

ar


Figure 24. Hay Phosphorus

0

0.5

1

1.5

2

2.5

3

Beaulac & Reckhow model

lb/a

c/ye

ar


Figure 28. Pasture TN Export vs TN applications

y = 0.0791x + 3.5782R2 = 0.9221

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250 300 350 400

applications lb/ac/year

tota

l nitr

ogen

exp

ort l

b/ac

/yr


2 points of calibration

Land Surface

RainRiver Reach










Calibration Reviews• Modeling Subcommittee• Tributary Strategy Work Group• Model Evaluation Group

____________________________________________________________________________CHESAPEAKE BAY WATERSHED MODEL

APPLICATION AND CALCULATION OF NUTRIENTAND SEDIMENT LOADINGS

Appendix E: Land Use and Linkages to the Airshed and Estuarine Models____________________________________________________________________________

A Report of theChesapeake Bay ProgramNutrient Subcommittee

Annapolis, MDAugust 1998

Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program


Topics


• Calibration

• Data




• Data



Types of Input Data

• Point sources• Land use• Nutrient loads to land• Management Actions


Point Sources

• Facility by facility list• Monthly data where available• Years 1984 - 1999• Estimates for future scenarios


Point Source Info• Point Source

Workgroup representation from

all states + DC• Documented on the

modeling subcommittee web site



Appendix F: Point Source Loadings____________________________________________________________________________





Land Use

}EMAPGIRAS

ForestImpervious Urban

Pervious UrbanFarms

AgriculturalCensus,CTIC

} CropHay

PastureMixed Open

Sources

Outputs

}Population

Estimations,Projections

Land UseData Base


Land Use

• Tributary Strategy Workgroup representation from





Appendix E: Land Use and Linkages to the Airshed and Estuarine Models____________________________________________________________________________





Nutrient Loads to Land

• Atmospheric Deposition• Fertilizer• Manure


Atmospheric Deposition

• Use national data source (NADP)

• Use Airshed model to determine wet deposition vs dry deposition

• Use Airshed model to estimate change due to management actions


AtmosphericDeposition

Nitrogen Atmospheric Deposition11.042 - 13.13910.288 - 11.0429.966 - 10.2889.662 - 9.9669.351 - 9.6629.17 - 9.351



Appendix D: - Precipitation & Meteorological Data Development & Atmospheric Deposition____________________________________________________________________________





Manure

• Use Agriculture Census to get animal numbers by type

• Use assumptions about manure production and applications

• Get monthly applications by crop type

• Overseen by Tributary Strategy Work Group


Manure Data ModelPasture

Beef

Uncollected

Collected

Spring/FallApplication

Daily Application

Crop

Enclosure

Barnyard

Volatilization

Volatilization

Daily Application

Storage

VolatilizationVolatilization

Volatilization

Runoff Runoff

DairySwineLayersBroilersTurkeys


Fertilizer

• Data From State Agriculture Agencies

• Modified for nutrient management

• Overseen by Modeling Subcommittee and Tributary Strategy Workgroup


Find Nutrient Management

Mineral

CropNeed

AtDep

Fertilizer

Manure

30% CropNeed


Find Nutrient Management

Mineral

CropNeed

AtDep

Fertilizer

Manure

30% CropNeed


Excess Manure

Mineral

CropNeedAtDep

Fertilizer

Manure30% Crop

Need


Manure

Mineral

AtDepCropNeed

30% CropNeed

Excess Manure


Manure

Mineral

AtDepCropNeed

30% CropNeed

Manureto move

Excess Manure


Manure and Fertilizer• Trib Strategy

Workgroup representation from





Appendix C: Agricultural Nutrient Loads____________________________________________________________________________





Topics


• Calibration

• Data




• DataData



Scenario Method

• Run 1985 - 1994 hydrology with land use, land management, and point sources held constant

• What are the expected annual loads if the state of management is Trib Strat?


Total Nitrogen Delivered to Tidal Potomac

0

10

20

30

40

50

60

70

80

1985 2000 Trib Strat LOCT 2010 Pristine

Mill

ion

lb/y

ear

DCPAWVMDVA

DRAFT


CBP Modeling Structure

Watershed Model

Chesapeake Bay Estuary Model Package

Hydrodynamic Model

Regional Acid Deposition Model


`

Average Water Claritywith watershed management

at 1985 levels

DRAFT


Average Water Claritywith watershed management

at Limit of CurrentTechnology

DRAFT


Phase 5


Collaborators• CBP

EPA CRC UMCES NRCS all state agencies

• USGS MD and VA

• U of MD.

• MDE• ICPRB• DCR


Major Partners

MDE/DCR TSWG Mod SCICPRB

USGS CBP Mod &Nut Teams

Stakeholder and Technical Input

TMDLneeds

PotomacStake-holdercoordination

CB stake-holder andtechnicalinformation

Technicalguidance


The right size forsegmentation


HSPF - lumped modelWhat is a reasonable size for lumping?

• Too big meaningful differences are

missed

• Too small can’t get the data can’t run the model


Phase 5 land segmentation

• Most counties are completely within a hydrogeomorphic region

• BMP and Crop data are not known on a finer scale in most cases

• Near the limit of computing capacity


What is a reasonable size for lumping?

• Too big meaningful differences are

missed• Too small

can’t get the data can’t run the model

River Simulation


Phase 5 RiverSegmentation

• Greater than 100 cfsor

• Has a flow gage

• Near the limit of meaningful data

• Consistent criterion


Putting the land andriver together




X 3000 acres

X 400 acres

X 900 acres



X 3000 acres

X 400 acres

X 900 acres


E T M Land Use

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1982 1985 1988 1991 1994 1997 2000 2003

Start of simulation End of simulation


E T M Land Use

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1982 1985 1988 1991 1994 1997 2000 2003

Start o f simulation End of simulation


E T MLand Use

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1982 1985 1988 1991 1994 1997 2000 2003

Start o f simulation End o f simulation


METData

ATDEPData

Land NPSExport

E T M

Final Output

NutrientApplication

Database

PSData


E T M


External Transfer Module

ManagementPractices

Time Series

Land UseTime Series

Time Series from Land Simulation

Time Series to River

Simulation

E T M


P5.D1 - Time varying calculation

ManagementPractices

Land UseTime Series 1985 reference

1990 calibration2000 progress

1985 reference1992 start of BMP implementation2000 progress

E T M


E T M BMPs

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1982 1985 1988 1991 1994 1997 2000 2003



E T M Land Use

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1982 1985 1988 1991 1994 1997 2000 2003



Other ETM Opportunities

• Seasonality• Urban flow considerations• Performance under extreme weather • Design life consideration• Ability to add any new BMP• Subgrid effects


Other p5 changes


Easier Operation

• Ability to split out small watersheds for simulation

• Ability to run partial scenarios• User-Friendly GUI for model output



Groundwater

• No groundwater lag in phase4.x

• Some ideas on the table for phase5, but . . .


Simulation Time

• P4 – 1984-1997 (used 1985-1994)

• P5 – 1984 – 2000 (calibration)• 2001 – 2001 (verification)


Rainfall

• Better information on a 5 km grid

• Use regression of weather pattern, latitude, longitude, and altitude.


Atmospheric Deposition

• Update of data and regression methods for observed data

• Update of model predicting change due to management actions



Better and extended data sets

• Point Source

• Water Diversions

• Septic


Better and extended data sets

• Fertilizer

• Manure

• Land Use =>


RESAC 2000 Land Cover• Delivered for Patuxent• Available by county-

segment• integrated with

impervious mapClass_namebare soil/rock/clay/sand/gravelcropsdecid trees and shrubsevergreen trees and shrubsgrassherb/sedge wetlandindustr/commerc/transp/highresmixed composition trees and grassresidentialwaterwooded wetland


RESAC 2000 Impervious Map

• Data on 30 m pixels• Able to combine with

LU Map


More land use types• Phase4

Forest Urban Hitil Lotil Hay Pasture Manure

• Phase5 Low intensity developed Moderate intensity developed High intensity develop corn wheat hay soy vegetables nursery tobacco cotton Pasture Grass fallow Deciduous forest Evergreen forest Mixed forest Deciduous wetlands Evergreen wetlands Emergent wetlands Bare rock/ mines/quarries Other barren (sand and soil) Water Major roads/interstates


New River Data

• Needed geomorphology of ~800 rivers Had data for ~200 Developed regression curves for each

region for• Bankfull depth• Bankfull width• Bottom depth


New Reservoir Data

• Phase4 Six simulated reservoirs

• Phase5 Forty simulated reservoirs


More Observations

• Phase4 16 stations for flow and water quality

• Phase5 70 water quality stations 280 flow stations


Calibration

• Better input data• More realistic simulation• More observations• Better calibration software• More calibrators• 5 more years of understanding

Documents

Chesapeake Bay Program Watershed Model 101