Texas Instream Flow Studies: Technical Overview

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Texas Instream Flow StudiesTechnical Overview

• Wendy Gordon, Ph.D.
• Texas Commission on Environmental Quality

October 2006
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The 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

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Paradigm 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

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Senate 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

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Legislative 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.
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• State drafted its methodology
• State contracted with NRC to peer review program
• Members included TNCs Brian Richter
• Report published in 2005

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Instream Flow Components
(recommended by National Research Council 2005)
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Flow Regime Functions
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Statewide 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."
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Ecosystem Diversity
Biotic Provinces
River Basins
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Interdisciplinary 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
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Steps 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
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Temporal and keyword queryfish studies conducted
1950s-90s
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Simple Conceptual Model
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Study Design

• Incorporate conceptual model of system
• Determine geographic scope of study
• Prioritize data deficiencies
• Develop basin-specific interdisciplinary study
  plan

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Steps 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
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Primary Disciplines
Physical Processes (Geomorphology)
Hydrology Hydraulics
Connectivity
Biology
Water Quality
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Biology

• Examine integrity of biological community
• Examine biodiversity within ecosystem
• Assess habitat-flow relationships

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Biology
Habitat Diversity
Biodiversity
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Water Quality

• Identify constituents of concern
• Assess low flow-water quality relationship
• Conduct water quality modeling studies

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Water Quality

• Dissolved oxygen
• pH
• Temperature
• Total dissolved solids
• Turbidity/clarity
• Nutrients

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Hydrology Hydraulics

• Calculate flow statistics
• Describe Wet, Normal, Dry conditions
• Model hydraulic characteristics

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Hydrology and Hydraulics
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Hydraulic and Habitat Modeling
Habitat changes with flow
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Habitat Modeling
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Habitat Modeling
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Physical 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

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River Styles Hierarchy
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Namoi River Basin, New South Wales
Watershed
0
100
200
300
400
Kilometers
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Namoi 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
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Middle Namoi Sub-basin
0
50
25
Kilometers
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Landscape 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
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Trailing 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
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Connectivity

• Hydrologic connectivity
• Upstream to down
• Channel to floodplain
• Groundwater/surface water interactions

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Steps 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
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Subsistence Flows
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Base Flows
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High Flow Pulses
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Overbank Flows
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Integration to Generatea Flow Regime
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Integration 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
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Projects 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

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Additional 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
  ml