The Texas Instream Flow Program

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The TexasInstream FlowProgram

• Barney Austin
• Surface Water Resources Division
• Texas Water Development Board

February 8th, 2006
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Instream flows methods

• Desktops methods
• Consensus Environmental Planning Criteria
• Lyons Method
• Comprehensive methods
• State methodology

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Desktop methods
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CPC for on-channel reservoirs
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CPC for direct diversions
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Comparison of flows
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Comprehensive methods
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In 2001Senate 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.

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Senate Bill 2

• Framework 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, and
• Complete priority studies by December 31, 2010.

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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.

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• Joint study accomplishments
• Interagency MOA
• (Executed Oct 17, 2002)
• Programmatic Work Plan
• (Final Dec 19, 2002)
• Technical Overview
• (Draft August 8, 2003)
• NAS review

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Summary of Agency Roles

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Texas Instream Flow Studies
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Timeframes for Priority Studies
Toledo Bend
Sabine R.
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Second Tier of Studies
Developed to provide future direction in studies
in the event priorities change or supplementary
resources are made available. These include

• Upper Guadalupe River
• Neches River
• Red River
• Upper Sabine River

Colorado R.
Two special studies include the Sulphur River
(on-going) and the Lower Colorado River
(monitoring).
Sulphur R.
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Hydrology Hydraulics
TCEQ - Water Availability Model (WAM)
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Hydraulic Modeling Brazos River
Detail Area
DOQQ photo taken February 4, 1995 7,500
cfs Boundary of FE Mesh used for flows below 3350
cfs is shown in green.
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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 contours 0.0m to 4.0m
FE mesh with velocity contours 0.0 to 2.25 mps
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Hydraulic Modeling Brazos River

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

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Fish habitat utilization studies
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Habitat Modeling Brazos River

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

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Modeling Issues Large woody debris
South Sulphur near Cooper

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

North Sulphur (near confluence)
Sulphur US of Patman (near Site 2)
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Modeling Issues Mesh Interpolation
Interpolating bathymetric single-beam data to the
finite element mesh Exploit the anisotropic shape
of the river cross-section for a better
interpolation Use flow-directional coordinate
system (either linear TWDB or curvilinear
CRWR)
 
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Modeling Issues Mesh Interpolation
Improved IDW interpolation using Mesh Elevating
and Bathymetry Adjusting Algorithms (MEBAA)
Standard IDW interpolation using Surface Water
Modeling System
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Modeling Issues - Geomorphology

• Bathymetry that changes with flow

Affects both hydraulic and habitat analysis
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Physical Processes

• Flushing flows (gt 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

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TCEQ Water Quality Specific Numeric Criteria

• Dissolved Oxygen
• Toxic Criteria
• Aquatic Life
• Human Health
• Bacteria ---- Contact Recreation
• Chloride, Sulfate, Total Dissolved Solids
• pH as absolute minima and maxima
• Temperature as absolute maxima

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Floodplain - Oxbow Lakes

• Study of river-floodplain interaction and
  connectivity

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National Academy of Sciences

• Evaluate science and methodology in key documents
• Review and provide advice on scientific and
  technical matters relevant to the Instream Flow
  Program
• Evaluate findings and recommendations of Tasks 1
  and 2 for consistency with the requirements of
  Texas law for the study of Instream Flows

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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)

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NAS Public meetings

• Austin Oct 2003
• San Antonio Jan 2004
• San Marcos Mar 2004
• Report released in March 2005

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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.

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Summary (the good stuff)

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

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Summary (the good stuff)

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

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• Major Recommendations

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• Two levels of oversight
• State level for management and program
  consistency
• Local goals and approaches

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• Clear definition for Sound Ecological
  Environment

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• Goalsstatewide and for individual subbasins

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• Ecological indicators
• Responsive to flow
• For monitoring validation
• Adaptive management
• Achieving Sound Ecological Environment

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• Existing information How will it guide detailed
  technical evaluations?

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• Spatial and temporal scale

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

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Planning
Water Quality

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

BE
Permitting
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• Independent, interdisciplinary peer review

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Specific recommendations

• Specific to each document
• Specific to elements
• Biology, HH, Physical Processes

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Next steps

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

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Instream Flow Study Program Results Will Be

• An essential database for conservation of fish
  and wildlife resources in Texas.
• Used in the States water rights permitting
  process, and
• Incorporated into future regional and state water
  plans.

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For more information
Barney Austin Texas Water Development Board Tel
463-8856 Email barney.austin_at_twdb.state.tx.us
http//www.twdb.state.tx.us/InstreamFlows/