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Texas Instream Flow Studies: Technical Overview Wendy Gordon, Ph.D. Texas Commission on Environmental Quality October 2006 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 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 Senate Bill 2 In 2001, the Texas Legislature directed TCEQ, TPWD & TWDB to: Establish data collection and evaluation program Determine flow conditions necessary to support a sound ecological environment in Texas rivers and streams Complete priority studies by December 31, 2010 Legislative Directive “…conduct studies and analyses to determine appropriate methodologies for determining flow conditions in the state’s rivers and streams necessary to support a sound ecological environment.” State drafted its methodology State contracted with NRC to peer review program Members included TNC’s Brian Richter Report published in 2005 Instream Flow Components (recommended by National Research Council 2005) Flow Regime Functions Component Hydrology Geomorphology Biology Water Quality Subsistence Flows Infrequent, low flows Increased deposition of fine & organic particles •Restricted aquatic habitat •Limited connectivity •Elevated temp •Reduced levels of DO Base Flows Normal flow conditions with variability •Maintain soil moisture & groundwater table •Maintain diversity of habitats •Suitable aquatic habitat •Connectivity along channel corridor Suitable in-channel water quality High Flow Pulses In-channel, short duration, high flows •Maintain channel & substrate characteristics •Prevent encroachment of riparian vegetation •Recruitment events for organisms •Connectivity to nearchannel water bodies Restore in-channel water quality after prolonged lowflow Overbank Flows Infrequent, high flows that exceed normal channel •Floodplain maintenance •Lateral channel movement •New habitat construction •Flush organic material into channel •Deposit nutrients in floodplain •Life phase cues for organisms •Riparian recruitment & maintenance •Connectivity with floodplain Restore water quality in floodplain water bodies 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." Ecosystem Diversity Biotic Provinces River Basins 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 Steps in TIFP Sub-Basin Studies Stakeholder Input Reconnaissance and Information Evaluation Stakeholder Input Goal Development Consistent with Sound Ecological Environment Study Design Stakeholder Input Multidisciplinary Data Collection and Evaluation Stakeholder Input Data Integration to Generate Flow Conditions Peer Review Peer Review Draft Study Report SB2 ends Post SB2 Stakeholder Input Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Peer Review Temporal and keyword query fish studies conducted 1950s-90s Simple Conceptual Model Sound Ecological Environment Subsistence Flows Conserve biological function •Water quality tolerances met •Key habitat thresholds maintained Base Flows Conserve biological / habitat diversity and water quality •Habitat for flow dependent species •Bank storage/moisture •Suitable temperatures / dissolved oxygen High Flow Pulses Overbank Flows Life history / geomorphic processes Floodplain maintenance •Fish spawning cues •Maintain channel •Sediment/nutrient transport •Moisture and nutrients to floodplain •Riparian recruitment Study Design Incorporate conceptual model of system Determine geographic scope of study Prioritize data deficiencies Develop basin-specific interdisciplinary study plan Steps in TIFP Sub-Basin Studies Stakeholder Input Reconnaissance and Information Evaluation Stakeholder Input Goal Development Consistent with Sound Ecological Environment Study Design Stakeholder Input Multidisciplinary Data Collection and Evaluation Stakeholder Input Data Integration to Generate Flow Conditions Peer Review Peer Review Draft Study Report SB2 ends Post SB2 Stakeholder Input Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Peer Review Primary Disciplines Hydrology & Hydraulics Physical Processes (Geomorphology) Connectivity Biology Water Quality Biology Examine integrity of biological community Examine biodiversity within ecosystem Assess habitat-flow relationships Biology Biodiversity Habitat Diversity Water Quality Identify constituents of concern Assess low flow-water quality relationship Conduct water quality modeling studies Water Quality Dissolved oxygen pH Temperature Total dissolved solids Turbidity/clarity Nutrients Hydrology & Hydraulics Calculate flow statistics Describe Wet, Normal, & Dry conditions Model hydraulic characteristics Hydrology and Hydraulics Brazos River at Richmond 08114000 80,000 70,000 50,000 40,000 30,000 20,000 10,000 Date Jan-05 Dec-04 Nov-04 Oct-04 Sep-04 Aug-04 Jul-04 Jun-04 May-04 May-04 Apr-04 Mar-04 0 Feb-04 Flow (cfs) 60,000 Hydraulic and Habitat Modeling Habitat changes with flow Habitat Modeling Habitat Modeling 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 River Styles Hierarchy Watershed Landscape Unit River Style Geomorphic Unit Hydraulic Unit Microhabitat Watershed area determined by drainage divide. Determines the boundary conditions within which rivers operate. Topographic unit determined on the basis of local relief, valley slope and morphology. Defines the valley-setting. Length of channel with a characteristic assemblage of geomorphic units. Instream and floodplain landforms (pools, bars, levees, backwaters, etc.) that reflect distinct form-process associations. Uniform patches of flow and substrate material within a geomorphic unit. Individual elements (e.g., logs, rocks, gravel patches) within a stream. Namoi River Basin, New South Wales Watershed 0 100 200 300 400 Kilometers Namoi River Basin, New South Wales Watershed Landscape Unit 0 25 50 100 Kilometers Legend – Landscape Units Liverpool plains Pillaga outwash Lowland plains Rugged metasediments Mid to lower Peel Rugged volcanics Pillaga Uplands Watershed Landscape Unit Middle Namoi Sub-basin River Style 0 25 50 Kilometers Landscape Unit Uplands Escarpment Base of the Escarpment Rounded Foothills Lowland Plain Channel Slope Channel and Valley Width Planform Valley Cross Section River Style Headwater Cut & Fill (Incised) Fan Gorge Vertically Floodplain Accreated Floodout Accumulation Cut & Fill Floodplain Throughput Transfer (Intact) Geomorphic Unit Riffle Hydraulic Unit Backwater Rippled flow on cobbles Barely perceptible flow on sand Floodplain Bar Smooth surface flow on cobbles Secondary Channel Pool Trailing Vegetation Submerged Macrophyte Cobbles Smooth surface flow on cobbles/sand Pool Run Microhabitat Barely perceptible flow on sand/boulders Large Woody Debris Boulders Sand Leaf Pack Connectivity Hydrologic connectivity Upstream to down Channel to floodplain Groundwater/surface water interactions Steps in TIFP Sub-Basin Studies Stakeholder Input Reconnaissance and Information Evaluation Stakeholder Input Goal Development Consistent with Sound Ecological Environment Study Design Stakeholder Input Multidisciplinary Data Collection and Evaluation Stakeholder Input Data Integration to Generate Flow Conditions Peer Review Peer Review Draft Study Report SB2 ends Post SB2 Stakeholder Input Final Study Report Next Steps: Implementation, Monitoring, and Adaptive Management Peer Review Subsistence Flows Identify Biological Considerations Identify Water Quality Constituents of Concern Calculate Low Flow Statistics Conduct Water Quality Modeling Studies Assess Low Flow - Water Quality Relationship Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality Other Biological Considerations Subsistence Flows Base Flows Assess Bedform Banks and Identify Biological Issues and Key Species Calculate Base Flow Statistics Collect Biological Data Model Hydraulic Characteristics in Relation to Flow Determine Habitat Criteria Assess Habitat-Flow Relationships, including Diversity Describe Wet, Normal, and Dry Years Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality Consider Biological and Riparian Issues Consider Water Quality Issues Base Flows High Flow Pulses Assess Active Channel Processes Develop Sediment Budgets Assess Channel Adjusting Flow Behavior Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality Describe Significant Habitat Conditions Consider Biological Issues Calculate High Flow Statistics Consider Water Quality Issues High Flow Pulses Overbank Flows Calculate Flood Frequency Statistics Assess Active Floodplain and Channel Processes Model Extent of Flood Events Assess Overbank Flow Behavior Primary Discipline Hydrology/Hydraulics Biology Geomorphology Water Quality Consider Biological Issues Conduct Riparian Studies Consider Water Quality Issues Estimate Riparian Requirements Overbank Flows Integration to Generate a Flow Regime Integration of Flow Components 4,000-10,000 cfs for 2-3 days Overbank Flows High Flow Pulses Base Flows Subsistence Flows Once every 3-5 years Channel Maintenance Riparian Connectivity, Seed dispersal Flooplain habitat 700-1500 cfs for 2-3 days 2-3 X per year every year Sediment transport Lateral connectivity Fish spawning Wet year Average year Dry year 1800 cfs for 2 days 1 X per yr every other year “Big River fish” spawning between Jul 15 - Aug 15 300-450 cfs maintain biodiversity and longitudinal connectivity 100-150 cfs 150-300 cfs 40-50 cfs 90-100 cfs Fish habitat Spring spawning Fish habitat Fish habitat 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 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 Additional Questions & Comments Contact: Wendy Gordon, TCEQ, 512-239-4174 [email protected] Kevin Mayes, TPWD, 512-754-6844, ext. 25 [email protected] Mark Wentzel, TWDB, 512-936-0823 [email protected] http://www.twdb.state.tx.us/instreamflows/ index.html