Environmental Flows Eric S. Hersh CE397 November 10, 2005 (National Geographic)

(USFWS, 2005)

(CSIRO, 2003)

(M.Bogan, Oregon State U)

topical development dams and reoperation Elaine, Andrew environmental flows (science) Eric, Becky water reserve (policy) Shane, Tyler

environmental flow definition  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

environmental flow requirements  Flows to sustain or restore the ecological functions (goods and services) of a river Fish and wildlife: habitat, migration, reproduction, biodiversity Fish and wildlife: habitat, migration, reproduction, biodiversity Recreation Recreation Navigation Navigation Hydropower Hydropower Waste assimilation Waste assimilation Water supply Water supply Food supply Food supply Flood and drought mitigation Flood and drought mitigation Nutrient delivery Nutrient delivery Coastal salinity regulation Coastal salinity regulation

interdisciplinary nature  Engineering: hydrology, hydraulics, water quality  Biology and ecology  Geomorphology and physical processes  Policy and regulation

international nature  Basin-wide management scale  Transboundary difficulties in prescribing and regulating environmental flow needs  Disparities in water availability and need, infrastructure, technical capacity, environmental awareness, regulatory structure

human impact (USBR, 2004)

historic river resource protection  Water quality U.S. Clean Water Act, 1972 U.S. Clean Water Act, 1972 Designated uses, water quality criteria Designated uses, water quality criteria “The objective of this Act is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters” “The objective of this Act is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters”  Water quantity Minimum flow (flat line) Minimum flow (flat line) “…nothing in this Act shall be construed to supersede or abrogate rights to quantities of water which have been established by any State.” “…nothing in this Act shall be construed to supersede or abrogate rights to quantities of water which have been established by any State.”

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

Question: manage flow for…?

Answer: everyone. the natural flow regime (Postel and Richter, 2003) Poff et al 1997

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

characterizing streamflow  Subsistence flow Water quality (temperature, DO, waste assimilation) Water quality (temperature, DO, waste assimilation) Riparian plant recruitment Riparian plant recruitment Purge invasive species Purge invasive species  Base flow Dominant flow condition in many rivers Dominant flow condition in many rivers Determines available habitat Determines available habitat Maidment et al 2005

characterizing streamflow  Flow pulses Within banks Within banks Macrophyte growth/SOD control Macrophyte growth/SOD control Nutrient and organic matter delivery Nutrient and organic matter delivery Shape the river channel geometry Shape the river channel geometry Longitudinal connectivity Longitudinal connectivity  Flood flows Overbank Overbank Lateral connectivity Lateral connectivity Riparian plant germination Riparian plant germination “Food bazaar” “Food bazaar” Maidment et al 2005

human impact  Artificial higher or lower low flows  Erratic daily flows from hydropower demand  Prevent or minimize floods  Disconnect floodplain  Channelize rivers and alter lotic habitat  Erase life cycle flow cues  Eliminate variability

human impact (Postel and Richter, 2003)

How much water does a river need? the big question…

water allocation 20 th century 21 st century what is this sustainable boundary? Ecosystem support allocation (Postel and Richter, 2003)

quantifying environmental flows  1950s-present  South Africa, Australia, United States  Hydrologic (Desktop) Models  Hydraulic Models  Habitat Models  Holistic Models

quantifying environmental flows  Hydrologic (Desktop) Models Simple, cheap, easy Simple, cheap, easy Use flow as an indicator for ecological and biological functions Use flow as an indicator for ecological and biological functions  Examples: Indicators of Hydrologic Alteration (IHA), The Nature Conservancy, 1997 Indicators of Hydrologic Alteration (IHA), The Nature Conservancy, 1997 Tennant Method (a.k.a. Montana Method), U.S. Fish and Wildlife Service, 1976 Tennant Method (a.k.a. Montana Method), U.S. Fish and Wildlife Service, 1976 Lyons Method, Texas Parks and Wildlife Dept., Lyons Method, Texas Parks and Wildlife Dept., 1979.

quantifying environmental flows  Hydraulic Models Correlate flow with available habitat area based on river channel geometry Correlate flow with available habitat area based on river channel geometry Physical proxy for in-stream ecology and biology Physical proxy for in-stream ecology and biology  Examples: Wetted Perimeter Method, Montana Dept. of Fish, Wildlife, and Parks, 1970s Wetted Perimeter Method, Montana Dept. of Fish, Wildlife, and Parks, 1970s R2-Cross Method, Colorado Div. of Wildlife, 1980s R2-Cross Method, Colorado Div. of Wildlife, 1980s

quantifying environmental flows  Habitat Models Complex, data intensive Complex, data intensive Use target species population data with hydraulic data to determine optimal habitat Use target species population data with hydraulic data to determine optimal habitat  Examples: Instream Flow Incremental Methodology (IFIM), U.S. FWS, 1970s. Includes Physical Habitat Simulation Model (PHABSIM). Mainly used for economically valuable or endangered species; legal credibility. Instream Flow Incremental Methodology (IFIM), U.S. FWS, 1970s. Includes Physical Habitat Simulation Model (PHABSIM). Mainly used for economically valuable or endangered species; legal credibility.

quantifying environmental flows  Holistic Models Very complex, resource and data intensive Very complex, resource and data intensive Comprehensive ecosystem assessment Comprehensive ecosystem assessment  Examples: Building Block Methodology (BBM), South Africa Dept. of Water Affairs and Forestry and Univ. of Cape Town, 1990s. Top-down approach. Building Block Methodology (BBM), South Africa Dept. of Water Affairs and Forestry and Univ. of Cape Town, 1990s. Top-down approach. Downstream Response to Imposed Flow Transformation (DRIFT), above plus Southern Waters Ecological Research and Consulting, 1990s Downstream Response to Imposed Flow Transformation (DRIFT), above plus Southern Waters Ecological Research and Consulting, 1990s

issues in quantifying environmental flows  Scaling  Ecological indicators  Integration  Data and resource availability  Legal/regulatory status

natural flow regime restoration (Postel and Richter, 2003)

implementation  Dam reoperation  Dam removal  Controlled floods  Adaptive management

dam removal (GZA GeoEnvironmental, 2000) Old Berkshire Mill Dam E. Branch Housatonic River, Massachusetts

dam removal (E.Hersh, 2003) Livermore Pond Dam Easton, Connecticut

dam removal Livermore Pond Dam Easton, Connecticut

questions for discussion How much water does a river need? Can this really be determined? How? What tools can be used to demonstrate the need for and value of environmental flows? What instruments can be used to implement environmental flow prescriptions?