The Texas
Instream Flow
Program
Barney Austin
Surface Water Resources Division
Texas 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
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Historical
Median
Flow
(cfs)
3,105
4,270
3,845
3,825
7,935
5,750
2,345
2,035
1,600
1,130
2,020
2,810
*7Q2 values.
Historical
Lyons
Flow
(cfs)
1,242
1,708
2,307
2,295
4,761
3,450
1,407
1,221
960
678*
808
1,124
Naturalized
Median
Flow
(cfs)
2,566
4,315
2,161
4,601
9,059
5,575
2,512
1,379
2,293
1,483
2,436
3,048
Naturalized
Lyons
Flow
(cfs)
1,026
1,726
1,297
2,761
5,436
3,345
1,507
838
1,376
890
975
1,219
CPC
Zone 1
Flow
(cfs)
2,566
4,315
2,161
4,601
9,059
5,575
2,512
1,379
2,293
1,483
2,436
3,048
CPC
Zone 2
Flow
(cfs)
964
1,773
1,343
1,835
3,159
2,596
1,139
709*
1,104
1,098
1,100
1,055
CPC
Zone 3
Flow*
(cfs)
734
734
734
734
734
734
734
734
734
734
734
734
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 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.
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 Element
Study Design
Coordinating
Agency
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
Instream Flow
Studies
Timeframes for Priority Studies
Subbasin
2003
2004
2005
2006
2007
2008
2009
Lower Guadalupe River
Lower Brazos River
Lower San Antonio River
Middle Trinity River
Lower Sabine River
Middle Brazos River
Toledo Bend
Sabine R.
2010
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.
Hydrology & Hydraulics
TCEQ - Water Availability Model (WAM)
Develop Finite Element mesh
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.
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
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
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)
Modeling Issues – Mesh Interpolation
Interpolating bathymetric
single-beam data to the
finite element mesh
Exploit the anisotropic
shape of the river crosssection for a better
interpolation
Use flow-directional
coordinate system (either
linear {TWDB} or
curvilinear {CRWR})
Typical radial bounding regions
MEBAA bounding boxes
Modeling Issues – Mesh Interpolation
Improved IDW interpolation using Mesh
Elevating and Bathymetry Adjusting
Algorithms (MEBAA)
Standard IDW interpolation using Surface Water
Modeling System
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


Build and bring nutrients to the floodplain
Extent and frequency from (existing?) 1-D models or aerial photos
Valley maintenance

(once per 1-10 years)
Q25-ish
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
Floodplain - Oxbow Lakes
Study of riverfloodplain
interaction and
connectivity
National Academy of Sciences
1. Evaluate science and methodology in key
2.
3.
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
NAS Committee
11 members, 4 from Texas:




Dr.
Dr.
Dr.
Dr.
David Maidment (UT, Austin)
Kirk Winemiller (TAMU)
Clark Hubbs (UT, Austin)
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
Integrate Technical Studies and
Develop Instream Flow
Recommendations
Study Report
Implementation
Monitoring, Evaluation,
and Adaptive Management
Spatial and
temporal scale
Sequential steps…
How to go from
technical evaluations to
flow recommendation
Water Quality
The Instream Flow
program should be
integrated with
other water-related
programs
Permitting
Planning
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, and
Incorporated into future regional and state
water plans.
For more information…
Barney Austin
Texas Water Development Board
Tel: 463-8856
Email: barney.austin@twdb.state.tx.us
http://www.twdb.state.tx.us/InstreamFlows/