The Texas Instream Flow Program

The TexasInstream Flow

Program

Barney AustinSurface Water Resources DivisionTexas Water Development Board

February 8th, 2006

Instream flows methods

Desktops methods : Consensus Environmental Planning

Criteria Lyons Method

Comprehensive methods : State methodology

Desktop methods

CPC for on-channel reservoirs

CPC for direct diversions

Comparison of flows…TABLE 6-2 BRAZOS RIVER ENVIRONMENTAL FLOWS

DERIVED BY DIFFERENT METHODS Month Historical

Median Flow (cfs)

Historical Lyons Flow (cfs)

Naturalized Median Flow (cfs)

Naturalized Lyons Flow (cfs)

CPC Zone 1 Flow (cfs)

CPC Zone 2 Flow (cfs)

CPC Zone 3 Flow* (cfs)

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

3,105 4,270 3,845 3,825 7,935 5,750 2,345 2,035 1,600 1,130 2,020 2,810

1,242 1,708 2,307 2,295 4,761 3,450 1,407 1,221 960 678* 808 1,124

2,566 4,315 2,161 4,601 9,059 5,575 2,512 1,379 2,293 1,483 2,436 3,048

1,026 1,726 1,297 2,761 5,436 3,345 1,507 838 1,376 890 975 1,219

2,566 4,315 2,161 4,601 9,059 5,575 2,512 1,379 2,293 1,483 2,436 3,048

964 1,773 1,343 1,835 3,159 2,596 1,139 709* 1,104 1,098 1,100 1,055

734 734 734 734 734 734 734 734 734 734 734 734

*7Q2 values.

Comprehensive methods

In 2001…Senate Bill 2

The Texas Legislature directed tri-agencies (TPWD, TWDB, and TCEQ) to: Establish and continuously maintain an instream flow data collection and evaluation program, and

Develop methodologies to determine flow conditions in Texas rivers and streams necessary to support a sound ecological environment.

Senate Bill 2Framework for Instream Flow Study

Program requires tri-agencies to:Share oversight of program studies.Share data, studies, analysis, information and reports.Establish a Work Plan that prioritizes studies and sets interim deadlines for publication of flow determinations, andComplete priority studies by December 31, 2010.

Senate Bill 2

Framework for Instream Flow Study also:Requires TCEQ to consider the results of completed studies in its review of any management plans, water rights, or interbasin transfers.

Joint study accomplishments:

• Interagency MOA (Executed: Oct 17, 2002)

• Programmatic Work Plan (Final: Dec 19, 2002)

• Technical Overview (Draft: August 8, 2003)

• NAS review…

Summary of Agency Roles

Instream Flow Study ElementCoordinating

Agency

Study Design Joint

Hydrological and Hydraulic Evaluation

TWDB

Biological Evaluation TPWD

Physical Processes Evaluation Joint

Water Quality Evaluation TCEQ

Integration Joint

Interpretation Joint

Study Report Joint

Monitoring and Validation Joint

Texas Texas Instream FlowInstream FlowStudiesStudies

Timeframes for Priority Studies

Subbasin 2003 2004 2005 2006 2007 2008 2009 2010

Lower Guadalupe River

Lower Brazos River

Lower San Antonio River

Middle Trinity River

Lower Sabine River

Middle Brazos River

Sabine R. Toledo Bend

Second Tier of Studies

Upper Guadalupe RiverNeches RiverRed RiverUpper Sabine River

Two special studies include the Sulphur River (on-going) and the Lower Colorado River (monitoring).

Developed to provide future direction in studies in the event priorities change or supplementary resources are made available. These include:

Sulphur R.

Colorado R.

Hydrology & Hydraulics

TCEQ - Water Availability Model (WAM)

Develop Finite Element mesh

Hydraulic Modeling – Brazos River

DOQQ photo taken February 4, 1995; ~7,500 cfsBoundary of FE Mesh used for flows below 3350 cfs is shown in green.

Detail Area

Hydraulic Modeling – Brazos River

Finite Element Mesh (approximate element resolution 8m x 10m)RMA-2 (depth averaged, hydrostatic Reynolds Averaged Navier-Stokes equations)1456 cfs shown

FE mesh with depth contours0.0m to 4.0m

FE mesh with velocity contours0.0 to 2.25 mps

Hydraulic Modeling – Brazos River

Photo of “Island” area, November 2, 2001.Flow is approximately 1500 cfs.

Fish habitat utilization studies

Habitat Modeling– Brazos River

Mesohabitats are delineated for 1456cfs using a grid-based GIS model

Modeling Issues – Large woody debris

Large Woody Debris (LWD) influences both hydraulics and habitat utilization analysis

North Sulphur (near confluence)

South Sulphur near Cooper

Sulphur US of Patman (near Site 2)

Modeling Issues – Mesh Interpolation

MEBAA bounding boxes

Typical radial bounding regions

Interpolating bathymetric single-beam data to the finite element meshExploit the anisotropic shape of the river cross-section for a better interpolationUse flow-directional coordinate system (either linear {TWDB} or curvilinear {CRWR})

Modeling Issues – Mesh Interpolation

Standard IDW interpolation using Surface Water Modeling System

Improved IDW interpolation using Mesh Elevating and Bathymetry Adjusting Algorithms (MEBAA)

Modeling Issues - Geomorphology

Bathymetry that changes with flow

Surveying (High Flow)

Modeling (Low Flow)

Affects both hydraulic and habitat analysis

Physical Processes

Flushing flows (> once per year) Restore/enhance riffle habitat Remove surficial and interstitial fine sediment Determined through study of sediment and hydraulic model

output

Channel maintenance (circa 1.5 per year) Maintain physical characteristics of the channel Study of flow-duration curves

Floodplain maintenance (once per 1-10 years) Build and bring nutrients to the floodplain Extent and frequency from (existing?) 1-D models or aerial

photos

Valley maintenance Q25-ish

Dissolved Oxygen Toxic Criteria Aquatic Life Human Health

Bacteria ---- Contact RecreationChloride, Sulfate, Total Dissolved SolidspH as absolute minima and maximaTemperature as absolute maxima

TCEQ – Water Quality & Specific Numeric Criteria

Floodplain - Oxbow Lakes

Study of river-floodplain interaction and connectivity

National Academy of Sciences

1. Evaluate science and methodology in key documents

2. Review and provide advice on scientific and technical matters relevant to the Instream Flow Program

3. Evaluate findings and recommendations of Tasks 1 and 2 for consistency with the requirements of Texas law for the study of Instream Flows

NAS Committee

11 members, 4 from Texas: Dr. David Maidment (UT, Austin) Dr. Kirk Winemiller (TAMU) Dr. Clark Hubbs (UT, Austin) Dr. Kenneth Dixon (UNT, Denton)

NAS Public meetings

Austin – Oct 2003 San Antonio – Jan 2004 San Marcos – Mar 2004

Report released in March 2005…

Summary (the good stuff)

Developing instream flow recommendations for rivers is one of the most difficult and important challenges in applied ecological and physical sciences today.

Summary (the good stuff)

The state of Texas shows an impressive commitment to designing and implementing an instream flow program…

Summary (the good stuff)

The Texas agencies are commended for proposing a prospective, comprehensive instream flow program…the program will provide enormous benefits to the state over the next several decades and beyond.

Major Recommendations:

Two levels of oversight: State level for

management and program consistency

Local goals and approaches

Clear definition for “Sound Ecological Environment”

Goals…statewide and for individual subbasins

Ecological indicators: Responsive to flow For monitoring &

validation Adaptive management Achieving “Sound

Ecological Environment”

Existing information… How will it guide detailed technical evaluations?

Set Goals

Study Design

Detailed Technical Evaluations

Monitoring, Evaluation, and

Adaptive Management

Study Report

Integrate Technical Studies and Develop

Instream Flow Recommendations

Implementation

Spatial and temporal scale

Sequential steps… How to go from technical evaluations to flow recommendation

The Instream Flow program should be integrated with other water-related programs

Water Quality

Planning

Permitting B&E

Independent, interdisciplinary peer review

Specific recommendations…

Specific to each document Specific to elements Biology, H&H, Physical Processes…

Next steps…

Update the TOD and PWP with stakeholder input Proceed with data collection in three priority basins Geomorphology conference upcoming…February 22nd. Stakeholder meetings in May???

Instream Flow Study Program Results Will Be:

An essential database for conservation of fish and wildlife resources in Texas. Used in the State’s water rights permitting process, andIncorporated into future regional and state water plans.

For more information…

http://www.twdb.state.tx.us/InstreamFlows/

Barney Austin

Texas Water Development Board

Tel: 463-8856

Email: barney.austin@twdb.state.tx.us