Title: Texas Instream Flow Studies: Technical Overview
1Texas Instream Flow StudiesTechnical Overview
- Wendy Gordon, Ph.D.
- Texas Commission on Environmental Quality
October 2006
2The Context of Instream Flow Science
- Acknowledgment of the importance of water flowing
in a stream to fish, wildlife and people - Acknowledgment that competing uses of water have
resulted in degraded river ecosystems - The challenge of developing methods to quantify
environmental or instream flow needs
3Paradigm Shift in Instream Flow Recommendations
- 1950s-70s development of first instream flow
methods yielding single minimum flow - Growing recognition of role of natural flow
regimes magnitude, duration, frequency, timing,
rate of change - Recent shift to consideration of entire flow
regime subsistence, base, high flow pulses,
overbank
4Senate Bill 2
In 2001, the Texas Legislature directed TCEQ,
TPWD TWDB to
- Establish data collection and evaluation program
- Determine flow conditions necessary tosupport a
sound ecological environmentin Texas rivers and
streams - Complete priority studies by December 31, 2010
5Legislative Directive
conduct studies and analyses to determine
appropriate methodologies for determining flow
conditions in the states rivers and streams
necessary to support a sound ecological
environment.
6- State drafted its methodology
- State contracted with NRC to peer review program
- Members included TNCs Brian Richter
- Report published in 2005
7Instream Flow Components
(recommended by National Research Council 2005)
8Flow Regime Functions
9Statewide Goal Support a Sound Ecological
Environment
A resilient, functioning ecosystem characterized
by intact, natural processes, and a balanced,
integrated, and adaptive community of organisms
comparable to that of the natural habitat of a
region."
10Ecosystem Diversity
Biotic Provinces
River Basins
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13Interdisciplinary Effort
Summary of the State of Knowledge Develop
Conceptual Model Tie Knowledge to Flow
Components Identify and Prioritize Knowledge
Gaps Develop Prioritized Research Agenda
Study Design
14Steps in TIFP Sub-Basin Studies
Reconnaissance and Information Evaluation
Stakeholder Input
Goal Development Consistent with Sound Ecological
Environment
Stakeholder Input
Peer Review
Study Design
Multidisciplinary Data Collection and Evaluation
Stakeholder Input
Data Integration to Generate Flow Conditions
Stakeholder Input
Peer Review
Draft Study Report
Stakeholder Input
Peer Review
Final Study Report
SB2 ends Post SB2
Next Steps Implementation, Monitoring, and
Adaptive Management
15Temporal and keyword queryfish studies conducted
1950s-90s
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19Simple Conceptual Model
20Study Design
- Incorporate conceptual model of system
- Determine geographic scope of study
- Prioritize data deficiencies
- Develop basin-specific interdisciplinary study
plan
21Steps in TIFP Sub-Basin Studies
Reconnaissance and Information Evaluation
Stakeholder Input
Goal Development Consistent with Sound Ecological
Environment
Stakeholder Input
Peer Review
Study Design
Multidisciplinary Data Collection and Evaluation
Stakeholder Input
Data Integration to Generate Flow Conditions
Stakeholder Input
Peer Review
Draft Study Report
Stakeholder Input
Peer Review
Final Study Report
SB2 ends Post SB2
Next Steps Implementation, Monitoring, and
Adaptive Management
22Primary Disciplines
Physical Processes (Geomorphology)
Hydrology Hydraulics
Connectivity
Biology
Water Quality
23Biology
- Examine integrity of biological community
- Examine biodiversity within ecosystem
- Assess habitat-flow relationships
24Biology
Habitat Diversity
Biodiversity
25Water Quality
- Identify constituents of concern
- Assess low flow-water quality relationship
- Conduct water quality modeling studies
26Water Quality
- Dissolved oxygen
- pH
- Temperature
- Total dissolved solids
- Turbidity/clarity
- Nutrients
27Hydrology Hydraulics
- Calculate flow statistics
- Describe Wet, Normal, Dry conditions
- Model hydraulic characteristics
28Hydrology and Hydraulics
29Hydraulic and Habitat Modeling
Habitat changes with flow
30Habitat Modeling
31Habitat Modeling
32Physical Processes (Geomorphology)
- Assess bedforms, banks, and floodplains
- Assess active floodplain and channel processes
- Assess channel adjusting and overbank flow
behavior - Develop sediment budgets
- Identify habitat features
33River Styles Hierarchy
34Namoi River Basin, New South Wales
Watershed
0
100
200
300
400
Kilometers
35Namoi River Basin, New South Wales
Watershed
Landscape Unit
50
0
100
25
Kilometers
Legend Landscape Units
Liverpool plains
Pillaga outwash
Lowland plains
Rugged metasediments
Rugged volcanics
Mid to lower Peel
Uplands
Pillaga
36Middle Namoi Sub-basin
0
50
25
Kilometers
37Landscape Unit
Uplands Escarpment Base of the
Escarpment Rounded
Foothills Lowland Plain
Channel Slope
Channel and Valley Width
Planform
Valley Cross Section
Head-water
Cut Fill (Incised)
Vertically Accreated Floodplain
Floodplain Accumulation
River Style
Floodout
Cut Fill (Intact)
Fan
Throughput
Transfer
Gorge
38Trailing Vegetation
Backwater
Rippled flow on cobbles
Submerged Macrophyte
Riffle
Barely perceptible flow on sand
Cobbles
Smooth surface flow on cobbles/sand
Floodplain
Large Woody Debris
Pool
Smooth surface flow on cobbles
Bar
Run
Secondary Channel
Boulders
Sand
Pool
Leaf Pack
Barely perceptible flow on sand/boulders
39Connectivity
- Hydrologic connectivity
- Upstream to down
- Channel to floodplain
- Groundwater/surface water interactions
40Steps in TIFP Sub-Basin Studies
Reconnaissance and Information Evaluation
Stakeholder Input
Goal Development Consistent with Sound Ecological
Environment
Stakeholder Input
Peer Review
Study Design
Multidisciplinary Data Collection and Evaluation
Stakeholder Input
Data Integration to Generate Flow Conditions
Stakeholder Input
Peer Review
Draft Study Report
Stakeholder Input
Peer Review
Final Study Report
SB2 ends Post SB2
Next Steps Implementation, Monitoring, and
Adaptive Management
41Subsistence Flows
42Base Flows
43High Flow Pulses
44Overbank Flows
45Integration to Generatea Flow Regime
46Integration of Flow Components
4,000-10,000 cfs for 2-3 days Once every 3-5
years Channel Maintenance Riparian Connectivity,
Seed dispersal Flooplain habitat
Overbank Flows
700-1500 cfs for 2-3 days 2-3 X per year every
year Sediment transport Lateral connectivity Fish
spawning
1800 cfs for 2 days 1 X per yr every other
year Big River fish spawning between Jul 15 -
Aug 15
High Flow Pulses
300-450 cfs maintain biodiversity and
longitudinal connectivity
Base Flows
40-50 cfs Fish habitat
90-100 cfs Fish habitat
150-300 cfs Spring spawning
100-150 cfs Fish habitat
Subsistence Flows
35 - 55 cfs Maintain water quality (35 cfs) and
key habitats in May (55 cfs)
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
NOV DEC
47Projects Funded for SB2
- Field-Based Mapping in support of a Geomorphic
Analysis of the Lower San Antonio River Subbasin - GIS-Based Geomorphic Analysis of the Lower San
Antonio River Subbasin - Field-Based Analysis in support of a Geomorphic
Assessment of the Brazos Navasota River
Subbasin - Geomorphic Equilibrium in Southeast Texas Rivers
- Distributional Survey and Habitat Utilization of
Freshwater Mussels - Developing a Large Woody Debris Budget for the
Sabine River, TX - Historical Zoogeography And Abundance Of Fishes
In Two Texas River Basins With An Annotated
Species List - Assessment of Hydrologic Alteration Software
- Geomorphic Studies of the Lower Brazos and
Navasota Rivers - Analysis of Existing Biological Data
- Biological Sampling on the Lower Brazos River,
Sabine River, and San Antonio River (3 separate
contracts) - Stakeholder Process
48Additional Questions Comments
- Contact
- Wendy Gordon, TCEQ, 512-239-4174
- wgordon_at_tceq.state.tx.us
- Kevin Mayes, TPWD, 512-754-6844, ext. 25
- Kevin.mayes_at_tpwd.state.tx.us
- Mark Wentzel, TWDB, 512-936-0823
- Mark.wentzel_at_twdb.state.tx.us
- http//www.twdb.state.tx.us/instreamflows/index.ht
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