the texas instream flow program
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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
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