Presenter: Eric S. Hersh, University of Texas at Austin Center for Research in Water Resources TRRMS Annual Symposium May 18, 2006 New Tools to Assess Hydrologic Alteration in Texas

Acknowledgements Co-authors: Co-authors: David Maidment, UT-Austin CRWR David Maidment, UT-Austin CRWR Jordan Furnans, TWDB Jordan Furnans, TWDB Mark Wentzel, TWDB Mark Wentzel, TWDB Wendy Gordon, TCEQ Wendy Gordon, TCEQ Thanks to: Thanks to: Joe Trungale, Trungale Engineering and Science, formerly TPWD Joe Trungale, Trungale Engineering and Science, formerly TPWD

environmental flow definition Water left in or released into a river system, often for managing some aspect of its conditions Water left in or released into a river system, often for managing some aspect of its conditions Endangered species protection Endangered species protection Healthy ecosystem Healthy ecosystem Sediment transport Sediment transport Commercial fisheries yield Commercial fisheries yield Freshwater inflows to bays and estuaries Freshwater inflows to bays and estuaries Waste assimilation Waste assimilation

flow- “the master variable” Controlling factor in riverine physical, biological, and chemical processes Controlling factor in riverine physical, biological, and chemical processes e.g.: water temperature, dissolved oxygen, available habitat, spawning cues, channel shape, substrate type, etc e.g.: water temperature, dissolved oxygen, available habitat, spawning cues, channel shape, substrate type, etc (Poff et al. 1997)

the natural flow regime (Postel and Richter 2003) Poff et al 1997

the natural flow regime Magnitude Magnitude Frequency Frequency Duration Duration Timing Timing Rate of change of hydrologic events Rate of change of hydrologic events

characterizing streamflow Subsistence flow Subsistence flow Water quality (temperature, DO, waste assimilation) Water quality (temperature, DO, waste assimilation) Restricted habitat and connectivity Restricted habitat and connectivity Base flow Base flow Dominant flow condition in many rivers Dominant flow condition in many rivers Determines available habitat Determines available habitat Maintains groundwater table Maintains groundwater table Maidment et al 2005

Flow pulses Flow pulses Within banks Within banks Longitudinal connectivity Longitudinal connectivity Nutrient and organic matter delivery Nutrient and organic matter delivery Sediment flushing Sediment flushing Flood flows Flood flows Overbank Overbank Lateral connectivity Lateral connectivity Restructure channel and floodplain Restructure channel and floodplain “Food bazaar” “Food bazaar” characterizing streamflow Maidment et al 2005

quantifying environmental flows 207 assessment tools (Tharme 2003) 207 assessment tools (Tharme 2003) 1950s-present 1950s-present South Africa, Australia, United States South Africa, Australia, United States Hydrologic (Desktop) Models Hydrologic (Desktop) Models Hydraulic Models Hydraulic Models Habitat Models Habitat Models Holistic Models Holistic Models

Senate Bill 2 In 2001, the tri-agencies (TPWD, TWDB, and TCEQ) were directed to: In 2001, the tri-agencies (TPWD, TWDB, and TCEQ) were directed to: Establish and maintain an instream flow data collection and evaluation program Establish and maintain an instream flow data collection and evaluation program Develop methodologies to determine flow conditions in Texas rivers and streams necessary to support a sound ecological environment Develop methodologies to determine flow conditions in Texas rivers and streams necessary to support a sound ecological environment

(Austin 2005)

hydrologic alteration software The Nature Conservancy USGS

The Indicators of Hydrologic Alteration (IHA) Richter et al., 1996 & 1997 Richter et al., 1996 & Annual Statistics 33 Annual Statistics Parametric (mean) or non-parametric (median) Parametric (mean) or non-parametric (median) One or two period analysis One or two period analysis Range of Variability Approach (RVA) to quantify hydrologic alteration Range of Variability Approach (RVA) to quantify hydrologic alteration 34 Environmental Flow Components (EFCs) from NAS review (Mallard et al. 2005) 34 Environmental Flow Components (EFCs) from NAS review (Mallard et al. 2005)

IHA Input: 20+ yrs of daily flow data recommended Input: 20+ yrs of daily flow data recommended Output: scorecards spreadsheet, summary and alteration graphs Output: scorecards spreadsheet, summary and alteration graphs

National HAT: USGS Fort Collins Science Center and Colorado State Univ. National HAT: USGS Fort Collins Science Center and Colorado State Univ. 171 indices from 13 papers (in Olden and Poff 2003), including the 33 IHA 171 indices from 13 papers (in Olden and Poff 2003), including the 33 IHA Input: daily and peak (optional) flow data Input: daily and peak (optional) flow data Six stream classifications Six stream classifications from Poff 1996 from Poff U.S. rivers 420 U.S. rivers Hydrologic Assessment Tool (HAT)

HAT New Jersey Hydrologic Index Tool (HIT) with NJ Department of Environmental Protection New Jersey Hydrologic Index Tool (HIT) with NJ Department of Environmental Protection Includes NJ Stream Classification Tool Includes NJ Stream Classification Tool Principal components analysis to identify 10 significant indices for each of 4 state-specific stream types Principal components analysis to identify 10 significant indices for each of 4 state-specific stream types Missouri and Massachusetts under development Missouri and Massachusetts under development Texas possibly next year Texas possibly next year

IHA/HAT Comparison Both are simple, user-friendly statistical tools to evaluate hydrologic characteristics Both are simple, user-friendly statistical tools to evaluate hydrologic characteristics Both are based on daily flow data time series which typically encompasses flow alteration Both are based on daily flow data time series which typically encompasses flow alteration Both have built-in temporal comparison tools; neither has spatial comparison tools Both have built-in temporal comparison tools; neither has spatial comparison tools HAT features more statistical routines and flexibility, but ‘significant’ indices chosen from a national dataset likely not representative of Texas conditions HAT features more statistical routines and flexibility, but ‘significant’ indices chosen from a national dataset likely not representative of Texas conditions Ecological significance of specific indices in both is unclear in Texas Ecological significance of specific indices in both is unclear in Texas

Texas Instream Flow Studies (Austin 2005)

TIFP priority basins n = 24 Brazos Sabine Trinity Guadalupe San Antonio

Spatial Patterns: Texas Streamflow

For streamflow periods of record at the 24 priority gages (average of 68 years): For streamflow periods of record at the 24 priority gages (average of 68 years): Across the range of flow variability, streamflow follows a sinusoidal pattern with a spring peak (May-June) and a fall trough (August-September) Across the range of flow variability, streamflow follows a sinusoidal pattern with a spring peak (May-June) and a fall trough (August-September) Signal is stronger to the east, muted to the west along the Texas coast Signal is stronger to the east, muted to the west along the Texas coast

Spatial Patterns: Texas Hydrology Q P

Q P

Q P

Q P

Spatial Patterns: Texas Streamflow For the period : For the period : precipitation is bimodal, irrespective of geography, with spring (May-June) and fall (September-October) peaks precipitation is bimodal, irrespective of geography, with spring (May-June) and fall (September-October) peaks Signal is expressed in magnitude (more precipitation to the east) but not in timing Signal is expressed in magnitude (more precipitation to the east) but not in timing

Spatial Patterns: Possible Causes Evapotranspiration Evapotranspiration More vegetation to the east More vegetation to the east More available water to the east More available water to the east Groundwater recharge Groundwater recharge Water demand and reservoir operations timing Water demand and reservoir operations timing

Future Work Continue to investigate flow regime characteristics and patterns which may impact instream flow analyses in the six priority basins Continue to investigate flow regime characteristics and patterns which may impact instream flow analyses in the six priority basins Compare the relative merits of IHA and HAT for the Texas Instream Flow Program Compare the relative merits of IHA and HAT for the Texas Instream Flow Program Recommend enhancements to one of the tools to increase effectiveness in Texas studies Recommend enhancements to one of the tools to increase effectiveness in Texas studies Work toward an integrated statewide stream classification system Work toward an integrated statewide stream classification system

Questions?

References Austin, B. (2005) The Texas Instream Flow Program. Presentation at the Environmental Flows Conference, Texas State University, San Marcos, October 31. Austin, B. (2005) The Texas Instream Flow Program. Presentation at the Environmental Flows Conference, Texas State University, San Marcos, October 31. Maidment, D., Montagna, P., Sansom, A., Ward, G., Winemiller, K. (2005). Scientific Principles for Definition of Environmental Flows. Statement for Environmental Flows Conference, Texas State University, San Marcos, October 31. Maidment, D., Montagna, P., Sansom, A., Ward, G., Winemiller, K. (2005). Scientific Principles for Definition of Environmental Flows. Statement for Environmental Flows Conference, Texas State University, San Marcos, October 31. National Research Council Committee (2005). The Science of Instream Flows: A Review of the Texas Instream Flow Program. Committee on Review of Methods for Establishing Instream Flows for Texas Rivers, National Research Council. The National Academies Press, Washington, D.C. National Research Council Committee (2005). The Science of Instream Flows: A Review of the Texas Instream Flow Program. Committee on Review of Methods for Establishing Instream Flows for Texas Rivers, National Research Council. The National Academies Press, Washington, D.C. Olden, J.D., and Poff, N.L. (2003). Redundancy and the choice of hydrologic indices for characterizing streamflow regimes. River Research and Applications, 19, Olden, J.D., and Poff, N.L. (2003). Redundancy and the choice of hydrologic indices for characterizing streamflow regimes. River Research and Applications, 19, Poff, N.L. (1996). A hydrogeography of unregulated streams in the United States and an examination of scale- dependence in some hydrological descriptors. Freshwater Biology, 36, Poff, N.L. (1996). A hydrogeography of unregulated streams in the United States and an examination of scale- dependence in some hydrological descriptors. Freshwater Biology, 36, Poff, N. L., Allan, J. D., Bain, M. B., Karr, J. R., Prestegaard, K.L., Richter, B. D., Sparks, R. E., and Stromberg, J. C. (1997). The natural flow regime. Bioscience, 47(11), Poff, N. L., Allan, J. D., Bain, M. B., Karr, J. R., Prestegaard, K.L., Richter, B. D., Sparks, R. E., and Stromberg, J. C. (1997). The natural flow regime. Bioscience, 47(11), Postel, S. and Richter, B. (2003). Rivers for Life: Managing Water for People and Nature. Island Press: Washington, D.C. Postel, S. and Richter, B. (2003). Rivers for Life: Managing Water for People and Nature. Island Press: Washington, D.C. Richter, B. D., Baumgartner, J. V., Powell, J., and Braun, D. P.(1996). A method for assessing hydrologic alteration within ecosystems. Conservation Biology, 10(4), Richter, B. D., Baumgartner, J. V., Powell, J., and Braun, D. P.(1996). A method for assessing hydrologic alteration within ecosystems. Conservation Biology, 10(4), Richter, B. D., Baumgartner, J. V., Wigington, R., and Braun, D. P. (1997). How much water does a river need? Freshwater Biology, 37(1), Richter, B. D., Baumgartner, J. V., Wigington, R., and Braun, D. P. (1997). How much water does a river need? Freshwater Biology, 37(1), Tharme, R. E. (2003). A global perspective on environmental flow assessment: Emerging trends in the development and application of environmental flow methodologies for rivers. River Research and Applications, 19(5-6), Tharme, R. E. (2003). A global perspective on environmental flow assessment: Emerging trends in the development and application of environmental flow methodologies for rivers. River Research and Applications, 19(5-6),