Environmental FlowsEnvironmental Flows

Eric S. HershEric S. HershCE397CE397

November 10, 2005November 10, 2005

(National Geographic)

(USFWS, 2005)

(CSIRO, 2003)

(M.Bogan, Oregon State U)

topical developmenttopical development

dams and reoperation

Elaine, Andrew

environmental flows (science)

Eric, Becky

water reserve (policy)

Shane, Tyler

environmental flow definitionenvironmental flow definition

Water left in or released into a river system, often Water left in or released into a river system, often for managing some aspect of its conditionsfor managing some aspect of its 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

environmental flow requirementsenvironmental flow requirements

Flows to sustain or restore the Flows to sustain or restore the ecological functionsecological functions (goods and services) of a river(goods and services) of a river

Fish and wildlife: habitat, migration, reproduction, biodiversityFish and wildlife: habitat, migration, reproduction, biodiversity RecreationRecreation NavigationNavigation HydropowerHydropower Waste assimilationWaste assimilation Water supplyWater supply Food supplyFood supply Flood and drought mitigationFlood and drought mitigation Nutrient deliveryNutrient delivery Coastal salinity regulationCoastal salinity regulation

interdisciplinary natureinterdisciplinary nature

Engineering: hydrology, hydraulics, water qualityEngineering: hydrology, hydraulics, water quality

Biology and ecologyBiology and ecology

Geomorphology and physical processesGeomorphology and physical processes

Policy and regulationPolicy and regulation

international natureinternational nature

Basin-wide management scaleBasin-wide management scale

Transboundary difficulties in prescribing and Transboundary difficulties in prescribing and regulating environmental flow needsregulating environmental flow needs

Disparities in water availability and need, Disparities in water availability and need, infrastructure, technical capacity, environmental infrastructure, technical capacity, environmental awareness, regulatory structureawareness, regulatory structure

human impacthuman impact

(USBR, 2004)

historic river resource protectionhistoric river resource protection Water qualityWater quality

U.S. Clean Water Act, 1972U.S. Clean Water Act, 1972 Designated uses, water quality criteriaDesignated uses, water quality criteria ““The objective of this Act is to restore and maintain the The objective of this Act is to restore and maintain the

chemical, physical, and biological integrity of the chemical, physical, and biological integrity of the Nation’s waters”Nation’s waters”

Water quantityWater quantity Minimum flow (flat line)Minimum flow (flat line) “…“…nothing in this Act shall be construed to supersede nothing in this Act shall be construed to supersede

or abrogate rights to quantities of water which have or abrogate rights to quantities of water which have been established by any State.”been established by any State.”

flow- “the master variable”flow- “the master variable”

Controlling factor in riverine Controlling factor in riverine physical, biological, and physical, biological, and chemical processeschemical processes

e.g.: water temperature, e.g.: water temperature, dissolved oxygen, available dissolved oxygen, available habitat, spawning cues, channel habitat, spawning cues, channel shape, substrate type, etcshape, substrate type, etc

Question: manage flow for…?Question: manage flow for…?

Answer: Answer: everyoneeveryone..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

characterizing streamflowcharacterizing streamflow

Subsistence flowSubsistence flow Water quality (temperature, DO, waste Water quality (temperature, DO, waste

assimilation)assimilation) Riparian plant recruitmentRiparian plant recruitment Purge invasive speciesPurge invasive species

Base flowBase flow Dominant flow condition in many riversDominant flow condition in many rivers Determines available habitatDetermines available habitat

Maidment et al 2005

characterizing streamflowcharacterizing streamflow Flow pulsesFlow pulses

Within banksWithin banks Macrophyte growth/SOD controlMacrophyte growth/SOD control Nutrient and organic matter deliveryNutrient and organic matter delivery Shape the river channel geometryShape the river channel geometry Longitudinal connectivityLongitudinal connectivity

Flood flowsFlood flows OverbankOverbank Lateral connectivityLateral connectivity Riparian plant germinationRiparian plant germination ““Food bazaar”Food bazaar”

Maidment et al 2005

human impacthuman impact

Artificial higher or lower low flowsArtificial higher or lower low flows

Erratic daily flows from hydropower demandErratic daily flows from hydropower demand

Prevent or minimize floodsPrevent or minimize floods

Disconnect floodplain Disconnect floodplain

Channelize rivers and alter lotic habitatChannelize rivers and alter lotic habitat

Erase life cycle flow cuesErase life cycle flow cues

Eliminate variabilityEliminate variability

human impacthuman impact

(Postel and Richter, 2003)

How much How much water does water does

a river a river need?need?

the big question…the big question…

water allocationwater allocation2020thth century century

2121stst century century

what is this sustainable boundary?

Ecosystem support allocationEcosystem support allocation

(Postel and Richter, 2003)

quantifying environmental flowsquantifying environmental flows

1950s-present1950s-present

South Africa, Australia, United StatesSouth Africa, Australia, United States

Hydrologic (Desktop) ModelsHydrologic (Desktop) Models

Hydraulic ModelsHydraulic Models

Habitat ModelsHabitat Models

Holistic ModelsHolistic Models

quantifying environmental flowsquantifying environmental flows

Hydrologic (Desktop) ModelsHydrologic (Desktop) Models Simple, cheap, easySimple, cheap, easy Use flow as an indicator for ecological and biological Use flow as an indicator for ecological and biological

functionsfunctions

Examples:Examples: Indicators of Hydrologic Alteration (IHA), The Nature Indicators of Hydrologic Alteration (IHA), The Nature

Conservancy, 1997Conservancy, 1997 Tennant Method (a.k.a. Montana Method), U.S. Fish Tennant Method (a.k.a. Montana Method), U.S. Fish

and Wildlife Service, 1976and Wildlife Service, 1976 Lyons Method, Texas Parks and Wildlife Dept., 1979.Lyons Method, Texas Parks and Wildlife Dept., 1979.

quantifying environmental flowsquantifying environmental flows

Hydraulic ModelsHydraulic Models Correlate flow with available habitat area based on Correlate flow with available habitat area based on

river channel geometryriver channel geometry Physical proxy for Physical proxy for in-streamin-stream ecology and biology ecology and biology

Examples:Examples: Wetted Perimeter Method, Montana Dept. of Fish, Wetted Perimeter Method, Montana Dept. of Fish,

Wildlife, and Parks, 1970sWildlife, and Parks, 1970s R2-Cross Method, Colorado Div. of Wildlife, 1980sR2-Cross Method, Colorado Div. of Wildlife, 1980s

quantifying environmental flowsquantifying environmental flows

Habitat ModelsHabitat Models Complex, data intensiveComplex, data intensive Use target species population data with hydraulic Use target species population data with hydraulic

data to determine optimal habitatdata to determine optimal habitat

Examples:Examples: Instream Flow Incremental Methodology (IFIM), Instream Flow Incremental Methodology (IFIM),

U.S. FWS, 1970s. Includes Physical Habitat U.S. FWS, 1970s. Includes Physical Habitat Simulation Model (PHABSIM). Mainly used for Simulation Model (PHABSIM). Mainly used for economically valuable or endangered species; economically valuable or endangered species; legal credibility.legal credibility.

quantifying environmental flowsquantifying environmental flows

Holistic ModelsHolistic Models Very complex, resource and data intensiveVery complex, resource and data intensive Comprehensive ecosystem assessmentComprehensive ecosystem assessment

Examples:Examples: Building Block Methodology (BBM), South Africa Building Block Methodology (BBM), South Africa

Dept. of Water Affairs and Forestry and Univ. of Dept. of Water Affairs and Forestry and Univ. of Cape Town, 1990s. Top-down approach.Cape Town, 1990s. Top-down approach.

Downstream Response to Imposed Flow Downstream Response to Imposed Flow Transformation (DRIFT), above plus Southern Transformation (DRIFT), above plus Southern Waters Ecological Research and Consulting, 1990sWaters Ecological Research and Consulting, 1990s

issues in quantifying issues in quantifying environmental flowsenvironmental flows

ScalingScaling

Ecological indicatorsEcological indicators

IntegrationIntegration

Data and resource availabilityData and resource availability

Legal/regulatory statusLegal/regulatory status

natural flow regime restorationnatural flow regime restoration

(Postel and Richter, 2003)

implementationimplementation

(Postel and Richter, 2003)

Dam reoperationDam reoperation

Dam removalDam removal

Controlled floodsControlled floods

Adaptive managementAdaptive management

dam removaldam removal

(GZA GeoEnvironmental, 2000)Old Berkshire Mill DamE. Branch Housatonic River, Massachusetts

dam removaldam removal

(E.Hersh, 2003)

Livermore Pond DamEaston, Connecticut

dam removaldam removal

Livermore Pond DamEaston, Connecticut

questions for discussionquestions for discussion

How much water does a river need? Can this How much water does a river need? Can this really be determined? How?really be determined? How?

What tools can be used to demonstrate the need What tools can be used to demonstrate the need for and value of environmental flows?for and value of environmental flows?

What instruments can be used to implement What instruments can be used to implement environmental flow prescriptions?environmental flow prescriptions?