Presenter: Presenter: Eric S. Hersh, University of Eric S. Hersh, University of Texas at Austin Center for Texas at Austin Center for Research in Water Resources Research in Water Resources TRRMS Annual Symposium TRRMS Annual Symposium May 18, 2006 May 18, 2006 New Tools to Assess New Tools to Assess Hydrologic Hydrologic Alteration Alteration in Texas in Texas
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New Tools to Assess Hydrologic Alteration in Texas
New Tools to Assess Hydrologic Alteration in Texas. Presenter: Eric S. Hersh, University of Texas at Austin Center for Research in Water Resources TRRMS Annual Symposium May 18, 2006. Acknowledgements. Co-authors: David Maidment, UT-Austin CRWR Jordan Furnans, TWDB Mark Wentzel, TWDB - PowerPoint PPT Presentation
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Presenter:Presenter:Eric S. Hersh, University of Texas Eric S. Hersh, University of Texas at Austin Center for Research in at Austin Center for Research in
Water left in or released into a river Water left in or released into a river system, often for managing some aspect of system, often for managing some aspect of its conditionsits conditions Endangered species protectionEndangered species protection Healthy ecosystemHealthy ecosystem Sediment transportSediment transport Commercial fisheries yieldCommercial fisheries yield Freshwater inflows to bays and estuariesFreshwater inflows to bays and estuaries Waste assimilationWaste assimilation
flow- “the master flow- “the master variable”variable”
Controlling factor in Controlling factor in riverine physical, riverine physical, biological, and biological, and chemical processeschemical processes
e.g.: water e.g.: water temperature, temperature, dissolved oxygen, dissolved oxygen, available habitat, available habitat, spawning cues, spawning cues, channel shape, channel shape, substrate type, etcsubstrate type, etc
(Poff et al. 1997)
the natural flow regimethe natural flow regime
(Postel and Richter 2003)
Poff et al 1997
the natural flow regimethe natural flow regime
MagnitudeMagnitude FrequencyFrequency DurationDuration TimingTiming Rate of change of hydrologic eventsRate of change of hydrologic events
Subsistence flowSubsistence flow Water quality (temperature, DO, waste Water quality (temperature, DO, waste
assimilation)assimilation) Restricted habitat and connectivityRestricted habitat and connectivity
Base flowBase flow Dominant flow condition in many riversDominant flow condition in many rivers Determines available habitatDetermines available habitat Maintains groundwater tableMaintains groundwater table
Maidment et al 2005
Flow pulsesFlow pulses Within banksWithin banks Longitudinal connectivityLongitudinal connectivity Nutrient and organic matter deliveryNutrient and organic matter delivery Sediment flushingSediment flushing
Flood flowsFlood flows OverbankOverbank Lateral connectivityLateral connectivity Restructure channel and floodplainRestructure channel and floodplain ““Food bazaar”Food bazaar”
characterizing characterizing streamflowstreamflowMaidment et al 2005
207 assessment tools (Tharme 2003)207 assessment tools (Tharme 2003) 1950s-present1950s-present South Africa, Australia, United StatesSouth Africa, Australia, United States
In 2001, the tri-agencies (TPWD, TWDB, In 2001, the tri-agencies (TPWD, TWDB, and TCEQ) were directed to:and TCEQ) were directed to: Establish and maintain an instream flow data Establish and maintain an instream flow data
collection and evaluation programcollection and evaluation program Develop methodologies to determine flow Develop methodologies to determine flow
conditions in Texas rivers and streams conditions in Texas rivers and streams necessary to support a sound ecological necessary to support a sound ecological environmentenvironment
The Indicators of The Indicators of Hydrologic Alteration (IHA)Hydrologic Alteration (IHA) Richter et al., 1996 & 1997Richter et al., 1996 & 1997 33 Annual Statistics33 Annual Statistics Parametric (mean) or non-parametric Parametric (mean) or non-parametric
(median)(median) One or two period analysisOne or two period analysis Range of Variability Approach (RVA) to Range of Variability Approach (RVA) to
HATHAT New Jersey Hydrologic Index Tool (HIT) New Jersey Hydrologic Index Tool (HIT)
with NJ Department of Environmental with NJ Department of Environmental ProtectionProtection Includes NJ Stream Classification ToolIncludes NJ Stream Classification Tool Principal components analysis to identify 10 Principal components analysis to identify 10
significant indices for each of 4 state-specific significant indices for each of 4 state-specific stream typesstream types
Missouri and Massachusetts under Missouri and Massachusetts under developmentdevelopment
Texas possibly next yearTexas possibly next year
IHA/HAT ComparisonIHA/HAT Comparison Both are simple, user-friendly statistical tools to Both are simple, user-friendly statistical tools to
Both are based on daily flow data time series which Both are based on daily flow data time series which typically encompasses flow alterationtypically encompasses flow alteration
Both have built-in temporal comparison tools; neither Both have built-in temporal comparison tools; neither has spatial comparison toolshas spatial comparison tools
HAT features more statistical routines and flexibility, HAT features more statistical routines and flexibility, but ‘significant’ indices chosen from a national dataset but ‘significant’ indices chosen from a national dataset likely not representative of Texas conditionslikely not representative of Texas conditions
Ecological significance of specific indices in both is Ecological significance of specific indices in both is unclear in Texasunclear in Texas
For streamflow periods of record at the 24 For streamflow periods of record at the 24 priority gages (average of 68 years): priority gages (average of 68 years): Across the range of flow variability, Across the range of flow variability,
streamflow follows a sinusoidal pattern with a streamflow follows a sinusoidal pattern with a spring peak (May-June) and a fall trough spring peak (May-June) and a fall trough (August-September)(August-September)
Signal is stronger to the east, muted to the Signal is stronger to the east, muted to the west along the Texas coastwest along the Texas coast
For the period 1961-1990:For the period 1961-1990: precipitation is bimodal, irrespective of precipitation is bimodal, irrespective of
geography, with spring (May-June) and fall geography, with spring (May-June) and fall (September-October) peaks(September-October) peaks
Signal is expressed in magnitude (more Signal is expressed in magnitude (more precipitation to the east) but not in timingprecipitation to the east) but not in timing
Spatial Patterns: Possible Spatial Patterns: Possible CausesCauses
Evapotranspiration Evapotranspiration More vegetation to the eastMore vegetation to the east More available water to the eastMore available water to the east
Groundwater rechargeGroundwater recharge Water demand and reservoir operations Water demand and reservoir operations
timingtiming
Future WorkFuture Work
Continue to investigate flow regime Continue to investigate flow regime characteristics and patterns which may impact characteristics and patterns which may impact instream flow analyses in the six priority instream flow analyses in the six priority basins basins
Compare the relative merits of IHA and HAT Compare the relative merits of IHA and HAT for the Texas Instream Flow Programfor the Texas Instream Flow Program
Recommend enhancements to one of the tools Recommend enhancements to one of the tools to increase effectiveness in Texas studiesto increase effectiveness in Texas studies
Work toward an integrated statewide stream Work toward an integrated statewide stream classification systemclassification system
Questions?Questions?
ReferencesReferences Austin, B. (2005) The Texas Instream Flow Program. Presentation at the Environmental Flows Austin, B. (2005) The Texas Instream Flow Program. Presentation at the Environmental Flows
Conference, Texas State University, San Marcos, October 31.Conference, Texas State University, San Marcos, October 31.
Maidment, D., Montagna, P., Sansom, A., Ward, G., Winemiller, K. (2005). Scientific Principles for 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 Definition of Environmental Flows. Statement for Environmental Flows Conference, Texas State University, San Marcos, October 31.University, San Marcos, October 31.
National Research Council Committee (2005). National Research Council Committee (2005). The Science of Instream Flows: A Review of the The Science of Instream Flows: A Review of the Texas Instream Flow ProgramTexas Instream Flow Program. Committee on Review of Methods for Establishing Instream Flows . Committee on Review of Methods for Establishing Instream Flows for Texas Rivers, National Research Council. The National Academies Press, Washington, D.C. 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 Olden, J.D., and Poff, N.L. (2003). Redundancy and the choice of hydrologic indices for characterizing streamflow regimes. characterizing streamflow regimes. River Research and Applications,River Research and Applications, 19, 101-121. 19, 101-121.
Poff, N.L. (1996). A hydrogeography of unregulated streams in the United States and an Poff, N.L. (1996). A hydrogeography of unregulated streams in the United States and an examination of scale-dependence in some hydrological descriptors. examination of scale-dependence in some hydrological descriptors. Freshwater BiologyFreshwater Biology, 36, 71-91., 36, 71-91.
Poff, N. L., Allan, J. D., Bain, M. B., Karr, J. R., Prestegaard, K.L., Richter, B. D., Sparks, R. E., and 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. Stromberg, J. C. (1997). The natural flow regime. BioscienceBioscience, 47(11), 769-784., 47(11), 769-784.
Postel, S. and Richter, B. (2003). Postel, S. and Richter, B. (2003). Rivers for Life: Managing Water for People and NatureRivers for Life: Managing Water for People and Nature. Island . Island Press: Washington, D.C.Press: Washington, D.C.
Richter, B. D., Baumgartner, J. V., Powell, J., and Braun, D. P.(1996). A method for assessing Richter, B. D., Baumgartner, J. V., Powell, J., and Braun, D. P.(1996). A method for assessing hydrologic alteration within ecosystems. hydrologic alteration within ecosystems. Conservation BiologyConservation Biology, 10(4), 1163-1174., 10(4), 1163-1174.
Richter, B. D., Baumgartner, J. V., Wigington, R., and Braun, D. P. (1997). How much water does a Richter, B. D., Baumgartner, J. V., Wigington, R., and Braun, D. P. (1997). How much water does a river need? river need? Freshwater BiologyFreshwater Biology, 37(1), 231-249., 37(1), 231-249.
Tharme, R. E. (2003). A global perspective on environmental flow assessment: Emerging trends in Tharme, R. E. (2003). A global perspective on environmental flow assessment: Emerging trends in the development and application of environmental flow methodologies for rivers. the development and application of environmental flow methodologies for rivers. River Research River Research and Applicationsand Applications, 19(5-6), 397-441., 19(5-6), 397-441.