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Texas Instream Flow Studies: Technical Overview Wendy Gordon, Ph.D. Texas Commission on Environmental Quality October 2006.

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Presentation on theme: "Texas Instream Flow Studies: Technical Overview Wendy Gordon, Ph.D. Texas Commission on Environmental Quality October 2006."— Presentation transcript:

1 Texas Instream Flow Studies: Technical Overview Wendy Gordon, Ph.D. Texas Commission on Environmental Quality October 2006

2 The Context of Instream Flow Science Acknowledgment of the importance of water flowing in a stream to fish, wildlife and people 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 Acknowledgment that competing uses of water have resulted in degraded river ecosystems The challenge of developing methods to quantify environmental or instream flow needs The challenge of developing methods to quantify environmental or instream flow needs

3 Paradigm Shift in Instream Flow Recommendations 1950s-70s development of first instream flow methods yielding single minimum flow 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 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 Recent shift to consideration of entire flow regime: subsistence, base, high flow pulses, overbank

4 Senate Bill 2 Establish data collection and evaluation program Establish data collection and evaluation program Determine flow conditions necessary to support a sound ecological environment in Texas rivers and streams Determine flow conditions necessary to support a sound ecological environment in Texas rivers and streams Complete priority studies by December 31, 2010 Complete priority studies by December 31, 2010 In 2001, the Texas Legislature directed TCEQ, TPWD & TWDB to:

5 …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. Legislative Directive

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

7 (recommended by National Research Council 2005) Instream Flow Components

8 ComponentHydrologyGeomorphologyBiology Water Quality Subsistence Flows Infrequent, low flows Increased deposition of fine & organic particles Restricted aquatic habitatRestricted aquatic habitat Limited connectivityLimited connectivity Elevated tempElevated temp Reduced levels ofReduced levels ofDO Base Flows Normal flow conditions with variability Maintain soil moisture & groundwater tableMaintain soil moisture & groundwater table Maintain diversity of habitatsMaintain diversity of habitats Suitable aquatic habitatSuitable aquatic habitat Connectivity alongConnectivity along channel corridor Suitable in-channel water quality High Flow Pulses In-channel, short duration, high flows Maintain channel & substrate characteristicsMaintain channel & substrate characteristics Prevent encroachment of riparian vegetationPrevent encroachment of riparian vegetation Recruitment events for organismsRecruitment events for organisms Connectivity to near- channel water bodiesConnectivity to near- channel water bodies Restore in-channel water quality after prolonged low- flow Overbank Flows Infrequent, high flows that exceed normal channel Floodplain maintenanceFloodplain maintenance Lateral channel movementLateral channel movement New habitat constructionNew habitat construction Flush organic material into channelFlush organic material into channel Deposit nutrients in floodplainDeposit nutrients in floodplain Life phase cues forLife phase cues fororganisms Riparian recruitment & maintenanceRiparian recruitment & maintenance Connectivity with floodplainConnectivity with floodplain Restore water quality in floodplain water bodies Flow Regime Functions

9 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."

10 River Basins Biotic Provinces Ecosystem Diversity

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13 Summary of the State of Knowledge Summary of the State of Knowledge Develop Conceptual Model & Develop Conceptual Model & Tie Knowledge to Flow Components Identify and Prioritize Knowledge Gaps Develop Prioritized Research Agenda Develop Prioritized Research Agenda Interdisciplinary Effort Study Design

14 Data Integration to Generate Flow Conditions Reconnaissance and Information Evaluation Study Design Multidisciplinary Data Collection and Evaluation Goal Development Consistent with Sound Ecological Environment Stakeholder Input Peer Review Draft Study Report Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Stakeholder Input Stakeholder Input Stakeholder Input Stakeholder Input Peer Review Peer Review SB2 ends Post SB2 Steps in TIFP Sub-Basin Studies

15 Temporal and keyword query fish studies conducted 1950s-90s

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19 Simple Conceptual Model Base FlowsSubsistence Flows Overbank Flows High Flow Pulses Conserve biological function Conserve biological / habitat diversity and water quality Life history / geomorphic processes Floodplain maintenance Moisture and nutrients to floodplain Riparian recruitment Water quality tolerances met Key habitat thresholds maintained Habitat for flow dependent species Bank storage/moisture Suitable temperatures / dissolved oxygen Fish spawning cues Maintain channel Sediment/nutrient transport Sound Ecological Environment

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

21 Data Integration to Generate Flow Conditions Reconnaissance and Information Evaluation Study Design Multidisciplinary Data Collection and Evaluation Goal Development Consistent with Sound Ecological Environment Stakeholder Input Peer Review Draft Study Report Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Stakeholder Input Stakeholder Input Stakeholder Input Stakeholder Input Peer Review Peer Review SB2 ends Post SB2 Steps in TIFP Sub-Basin Studies

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

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

24 Biology Habitat Diversity Biodiversity

25 Water Quality Identify constituents of concern Identify constituents of concern Assess low flow-water quality relationship Assess low flow-water quality relationship Conduct water quality modeling studies Conduct water quality modeling studies

26 Water Quality Dissolved oxygen Dissolved oxygen pH pH Temperature Temperature Total dissolved solids Total dissolved solids Turbidity/clarity Turbidity/clarity Nutrients Nutrients

27 Hydrology & Hydraulics Calculate flow statistics Calculate flow statistics Describe Wet, Normal, & Dry conditions Describe Wet, Normal, & Dry conditions Model hydraulic characteristics Model hydraulic characteristics

28 Hydrology and Hydraulics

29 Hydraulic and Habitat Modeling Habitat changes with flow

30 Habitat Modeling

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32 Physical Processes (Geomorphology) Assess bedforms, banks, and floodplains Assess bedforms, banks, and floodplains Assess active floodplain and channel processes Assess active floodplain and channel processes Assess channel adjusting and overbank flow behavior Assess channel adjusting and overbank flow behavior Develop sediment budgets Develop sediment budgets Identify habitat features Identify habitat features

33 River Styles Hierarchy Watershed Watershed area determined by drainage divide. Determines the boundary conditions within which rivers operate. Geomorphic Unit Instream and floodplain landforms (pools, bars, levees, backwaters, etc.) that reflect distinct form-process associations. River Style Length of channel with a characteristic assemblage of geomorphic units. Landscape Unit Topographic unit determined on the basis of local relief, valley slope and morphology. Defines the valley-setting. Hydraulic Unit Uniform patches of flow and substrate material within a geomorphic unit. Microhabitat Individual elements (e.g., logs, rocks, gravel patches) within a stream.

34 Kilometers Watershed Namoi River Basin, New South Wales

35 Watershed Landscape Unit Namoi River Basin, New South Wales Kilometers Legend – Landscape Units Rugged metasediments Rugged volcanics Uplands Pillaga outwash Pillaga Mid to lower Peel Lowland plains Liverpool plains

36 Middle Namoi Sub-basin Watershed Landscape Unit River Style Kilometers

37 Channel and Valley Width Channel Slope Valley Cross Section Planform Uplands Escarpment Base of the Escarpment Rounded Foothills Lowland Plain Landscape Unit River Style Head- water Gorge Fan Cut & Fill (Incised) Cut & Fill (Intact) Vertically Accreated Floodplain Throughput Floodout Transfer Floodplain Accumulation

38 Geomorphic Unit Hydraulic Unit Microhabitat Riffle Floodplain Run Pool Bar Secondary Channel Pool Backwater Trailing Vegetation Submerged Macrophyte Cobbles Large Woody Debris Boulders Sand Leaf Pack Rippled flow on cobbles Smooth surface flow on cobbles Smooth surface flow on cobbles/sand Barely perceptible flow on sand/boulders Barely perceptible flow on sand

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

40 Data Integration to Generate Flow Conditions Reconnaissance and Information Evaluation Study Design Multidisciplinary Data Collection and Evaluation Goal Development Consistent with Sound Ecological Environment Stakeholder Input Peer Review Draft Study Report Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Stakeholder Input Stakeholder Input Stakeholder Input Stakeholder Input Peer Review Peer Review SB2 ends Post SB2 Steps in TIFP Sub-Basin Studies

41 Identify Biological Considerations Calculate Low Flow Statistics Identify Water Quality Constituents of Concern Conduct Water Quality Modeling Studies Assess Low Flow - Water Quality Relationship Subsistence Flows Other Biological Considerations Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality Subsistence Flows

42 Assess Bedform and Banks Model Hydraulic Characteristics in Relation to Flow Determine Habitat Criteria Describe Wet, Normal, and Dry Years Calculate Base Flow Statistics Collect Biological Data Assess Habitat-Flow Relationships, including Diversity Consider Water Quality Issues Consider Biological and Riparian Issues Base Flows Identify Biological Issues and Key Species Base Flows Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality

43 Assess Active Channel Processes Develop Sediment Budgets Assess Channel Adjusting Flow Behavior High Flow Pulses Calculate High Flow Statistics Consider Water Quality Issues Consider Biological Issues Describe Significant Habitat Conditions High Flow Pulses Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality

44 Assess Overbank Flow Behavior Overbank Flows Model Extent of Flood Events Conduct Riparian Studies Consider Biological Issues Estimate Riparian Requirements Consider Water Quality Issues Calculate Flood Frequency Statistics Assess Active Floodplain and Channel Processes Overbank Flows Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality

45 Integration to Generate a Flow Regime

46 Integration of Flow Components Overbank Flows High Flow Pulses Base Flows Subsistence Flows JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC cfs Maintain water quality (35 cfs) and key habitats in May (55 cfs) cfs Fish habitat cfs Fish habitat cfs Spring spawning cfs Fish habitat cfs maintain biodiversity and longitudinal connectivity 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 4,000-10,000 cfs for 2-3 days Once every 3-5 years Channel Maintenance Riparian Connectivity, Seed dispersal Flooplain habitat Wet year Average year Dry year

47 Projects Funded for SB2 Field-Based Mapping in support of a Geomorphic Analysis of the Lower San Antonio River Subbasin 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 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 Field-Based Analysis in support of a Geomorphic Assessment of the Brazos & Navasota River Subbasin Geomorphic Equilibrium in Southeast Texas Rivers Geomorphic Equilibrium in Southeast Texas Rivers Distributional Survey and Habitat Utilization of Freshwater Mussels Distributional Survey and Habitat Utilization of Freshwater Mussels Developing a Large Woody Debris Budget for the Sabine River, TX 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 Historical Zoogeography And Abundance Of Fishes In Two Texas River Basins With An Annotated Species List Assessment of Hydrologic Alteration Software Assessment of Hydrologic Alteration Software Geomorphic Studies of the Lower Brazos and Navasota Rivers Geomorphic Studies of the Lower Brazos and Navasota Rivers Analysis of Existing Biological Data Analysis of Existing Biological Data Biological Sampling on the Lower Brazos River, Sabine River, and San Antonio River (3 separate contracts) Biological Sampling on the Lower Brazos River, Sabine River, and San Antonio River (3 separate contracts) Stakeholder Process Stakeholder Process

48 Additional Questions & Comments Contact: Contact: Wendy Gordon, TCEQ, Wendy Gordon, TCEQ, Kevin Mayes, TPWD, , ext. 25 Kevin Mayes, TPWD, , ext. 25 Mark Wentzel, TWDB, Mark Wentzel, TWDB, /index.html /index.html


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