Transcript Environmental Flows Overheads

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
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Water left in or released into a river system, often
for managing some aspect of its conditions
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Endangered species protection
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Healthy ecosystem
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Sediment transport
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Commercial fisheries yield
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Freshwater inflows to bays and estuaries
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Waste assimilation
environmental flow requirements
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Flows to sustain or restore the ecological functions
(goods and services) of a river
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Fish and wildlife: habitat, migration, reproduction, biodiversity
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Recreation
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Navigation
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Hydropower
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Waste assimilation
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Water supply
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Food supply
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Flood and drought mitigation
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Nutrient delivery
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Coastal salinity regulation
interdisciplinary nature
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Engineering: hydrology, hydraulics, water quality
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Biology and ecology
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Geomorphology and physical processes
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Policy and regulation
international nature
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Basin-wide management scale
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Transboundary difficulties in prescribing and
regulating environmental flow needs
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Disparities in water availability and need,
infrastructure, technical capacity, environmental
awareness, regulatory structure
human impact
(USBR, 2004)
historic river resource protection
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Water quality
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U.S. Clean Water Act, 1972
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Designated uses, water quality criteria
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“The objective of this Act is to restore and maintain the
chemical, physical, and biological integrity of the
Nation’s waters”
Water quantity
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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.”
flow- “the master variable”
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Controlling factor in riverine
physical, biological, and
chemical processes
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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
Poff et al 1997
(Postel and Richter, 2003)
the natural flow regime
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Magnitude
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Frequency
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Duration
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Timing
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Rate of change of hydrologic events
characterizing streamflow
Maidment et al 2005
 Subsistence
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Water quality (temperature, DO, waste
assimilation)
Riparian plant recruitment
Purge invasive species
 Base
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flow
flow
Dominant flow condition in many rivers
Determines available habitat
characterizing streamflow
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Flow pulses
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Within banks
Macrophyte growth/SOD control
Nutrient and organic matter delivery
Shape the river channel geometry
Longitudinal connectivity
Flood flows
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Overbank
Lateral connectivity
Riparian plant germination
“Food bazaar”
Maidment et al 2005
human impact
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Artificial higher or lower low flows
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Erratic daily flows from hydropower demand
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Prevent or minimize floods
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Disconnect floodplain
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Channelize rivers and alter lotic habitat
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Erase life cycle flow cues
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Eliminate variability
human impact
(Postel and Richter, 2003)
the big question…
How much
water does
a river
need?
water allocation
20th century
Ecosystem support allocation
21st century
(Postel and Richter, 2003)
what is this
sustainable
boundary?
quantifying environmental flows
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1950s-present
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South Africa, Australia, United States
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Hydrologic (Desktop) Models
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Hydraulic Models
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Habitat Models
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Holistic Models
quantifying environmental flows
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Hydrologic (Desktop) Models
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Simple, cheap, easy
Use flow as an indicator for ecological and
biological functions
Examples:
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Indicators of Hydrologic Alteration (IHA), The
Nature Conservancy, 1997
Tennant Method (a.k.a. Montana Method), U.S.
Fish and Wildlife Service, 1976
Lyons Method, Texas Parks and Wildlife Dept.,
1979.
quantifying environmental flows
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Hydraulic Models
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Correlate flow with available habitat area based on
river channel geometry
Physical proxy for in-stream ecology and biology
Examples:
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Wetted Perimeter Method, Montana Dept. of Fish,
Wildlife, and Parks, 1970s
R2-Cross Method, Colorado Div. of Wildlife, 1980s
quantifying environmental flows
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Habitat Models
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Complex, data intensive
Use target species population data with hydraulic
data to determine optimal habitat
Examples:
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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
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Holistic Models
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Very complex, resource and data intensive
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Comprehensive ecosystem assessment
Examples:
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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
issues in quantifying
environmental flows
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Scaling
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Ecological indicators
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Integration
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Data and resource availability
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Legal/regulatory status
natural flow regime restoration
(Postel and Richter, 2003)
implementation
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Dam reoperation
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Dam removal
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Controlled floods
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Adaptive management
(Postel and Richter, 2003)
dam removal
Old Berkshire Mill Dam
E. Branch Housatonic River, Massachusetts
(GZA GeoEnvironmental, 2000)
dam removal
Livermore Pond Dam
Easton, Connecticut
(E.Hersh, 2003)
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?