Transcript cee6490EnvironmentalEffectsManagement

Management to Mitigate
Environmental Effects of
Dams
David Rosenberg
CEE 6490 – Integrated River Basin /
Watershed Planning & Management
Learning Objectives
1. Quantify effects of dams on river
channels and indicator species
2. Describe major approaches to
mitigate effects
3. Determine effects of mitigation
approaches on key indicators
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Environmental Effects
• Altered flow regimes
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Flood frequency and duration
Mean annual flow
Base (minimum) flows
Temperature
Channel degradation
Sediment trapping
Watershed fragmentation
Key indicator species
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Historical Longitudinal Bed Profile
Glen Canyon Dam, 1956
(Schmidt)
960
1956 Water Surface
2000 Water Surface
Elevation, in meters
955
950
1956 Bed
945
Eroded Gravel 1956-2000
2000 Bed
940
Top of Buried Gravel 1956
935
0
5
10
15
20
Distance downstream from Glen Canyon Dam, in kilometers
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Bed Degradation
Glen Canyon Dam, 1956 to 2000
(Schmidt)
960
1956 Water Surface
2000 Water Surface
Elevation, in meters
955
950
1956 Bed
945
Eroded Gravel 1956-2000
2000 Bed
940
Top of Buried Gravel 1956
935
0
5
10
15
20
Distance downstream from Glen Canyon Dam, in kilometers
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Maximum Bed Degradation below
some Large Dams
(Williams and Wolman, 1984)
• Colorado
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Glen Canyon: 7.3 m/9 years
Hoover: 7.5 m/13 years
Davis: 5.8 m/26 years
Parker: 4.6 m/27 years
• Jemez
– Jemez Canyon: 2.8 m/12 years
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• Arkansas
– John Martin: 0.9 m/30 years
• Missouri
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–
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Fort Peck: 1.8 m/36 years
Garrison: 1.7 m/23 years
Fort Randall: 2.6 m/23 years
Gavin’s Point: 2.5 m/19
years
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Key Indicator Species
• Typically describe environmental impacts on key indicator
species (often a fish!) – NEPA and ESA driven
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June sucker, Provo River, Utah
Azraq killfish, Azraq, Jordan
Bonneville cutthroat trout, Bear River
Delta smelt, Sacramento & San Joaquin Delta, CA
Coho and chinook salmon, Klamath River, CA
And many, many, many others
• Environmental management typically mitigates for species
of concern – improve habitat
• Avoid focus on ecosystem function
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Key Indicator Species
Salmon Spawning and Ocean Counts, CA
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Mitigation Approaches
• Operational
– Change timing and duration of releases
• Structural
– Multi-stage elevation releases
• Temperature control structures
• Thermal curtains
– Fish screens
– Fish ladders
• Management
– Environmental water accounts
• Remove dams (possibly in April)
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Changing Reservoir Releases
Glen Canyon Dam, Colorado River (J. Schmidt)
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(A) Pre- and (B) Post-Dam Sediment Fluxes
Dist.
Sediment
below
Location
Reduction
Dam
(mmt)
(km)
Marble
Canyon
25
57 to 0.3
Upper
Grand
Canyon
170
83 to 14
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Significance of Fine-Sediment Deposits
• Distinctive attribute of the
pre-dam riverscape
• Campsites
• Creates stagnant flow and
backwater habitat at some
discharges
• Riparian ecosystem
substrate
• Deposits contain
archaeological resources or
stabilize those resources
• Transport creates turbidity
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General Pattern of Sand Bar Change
(Badger Creek Rapids)
1956
Sand eroded
from eddies
1999
Sand eroded by
wind; not
replaced by
flood deposition
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3000
Glen Canyon Dam Release Experiments
DISCHARGE, IN CUBIC METERS PER SECOND
2500
2000
experiments
interim low
fluctuating flows
modified low
fluctuating flows
1996
Controlled
Flood
1500
maximum
powerplant
releases
1000
500
sediment conservation
0
1990
1992
1994
1996
1998
2000
1. Reduce range of
daily
fluctuations
(erosion control)
2. Spiked “floods”
(rebuild high
elevation sand
bars)
3. Sustain low
flows (trap fine
sediment)
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November 2004 Sediment Mobilization Flows
lost
hydropower
revenue ~ $1
million
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Costs of Modified Releases
Release Regime
Cost (lost hydro revenue)
[$ Millions]
Interim low fluctuating
flows (per year)
$36
Modified low fluctuating
flows (per year)
$44
Annual
revenue in
2003/2004
1996 controlled flood
$4
~ $140
million/yr
2003/2004 experimental
releases
Restoration budget
(FY 2004)
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$2.85 (autumn)
$1.6 (winter)
$11.1
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But
…Postscript
Glen Canyon
Dam
Newly built sand bars were immediately eroded by the large
flow fluctuations, designed to disadvantage spawning trout
Cutbank 1 day after resumption of
large fluctuations
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Temperature-Controlled Release Tower
Shasta Dam, Sacramento River, CA
• 4.5 MAF storage
• Dam height 602 ft.
• Max. tower depth 350 ft.
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Thermal Curtain
(Burgi, 1995; Vermeyan, 1995)
• Lewiston Lake, Clear
Creak, California
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Comparing Temperature Control
Methods (Burgi, 1995)
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What did the fish say when it ran
into the wall?
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Fish Ladders
• Oroville Dam (right)
• John Day Dam (bottom right)
• Bonneville (below)
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Fish Ladder at Coleman Fish Hatchery
Sacramento River, CA
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Fish Screens
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Environmental Water Accounts
(Hollingshead, 2006)
• Sac. & San Joaquin Delta
• 500 plants & animals
• Supplies
– 2/3 residential and
commercial users
– 7 million ac farmland
• 21 Federal & State
agencies (i.e, CALFED)
• Major water exports
– CVP: 8,000 af/day
– SWP: 15,000 af/day
• Endangered species
– Chinook salman, delta smelt, steelhead rainbow trout
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CALFED Operations
• Purchase assets (year round)
– Long-term, spot market, and options to water on CA market
– Storage in reservoirs South of Delta
• 500 cfs capacity to move purchased assets South of Delta
(July to August)
• Curtail export pumping (critical times to fish)
– Reimburse projects (SWP and CVP) for cutbacks
– Deploy purchased assets which are stored South of Delta
• Real-time operations that respond to ecological and fish
events
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CALFED Actions
• $19 – 65 million/year in purchases
• 155 – 230 TAF/year
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Conclusions
• Can quantify environmental impacts of dams and
reservoirs with numerous indicators
• Site-specific factors determine type and extent of
impacts
• Regulation-imposed mitigation often required
• Structural, operational, and management
approaches to mitigate impacts
• Often pose significant costs
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References
Burgi, P. H. "The Evolving Role of Hydraulic Structures - From Development to
Management of Water." Issues and Directions in Hydraulics - An Iowa
Hydraulics Colloquium, Iowa City, Iowa,
http://www.usbr.gov/pmts/hydraulics_lab/history/transition/trans1.html.
Hollinshead, S. P., and Lund, J. R. (2006). "Optimization of environmental water
purchases with uncertainty." Water Resources Research, 42, W08403,
http://dx.doi.org/10.1029/2005WR004228.
Mostafa, M. G. (1957). "River-bed degradation below large capacity reservoirs."
American Society of Civil Engineers Transactions, 122, 688-704.
Vermeyen, T. B. "Use of Temperature Control Curtains to Modify Reservoir
Release Temperatures." ASCE's First International Conference on Water
Resources Engineering, San Antonio, Texas,
http://www.usbr.gov/pmts/hydraulics_lab/tvermeyen/asce95m/index.html.
Williams, G. P., and Wolman, M. G. (1984). "Downstream effects of dams on
alluvial rivers." Professional Paper 1286, U.S. Geological Survey, Washington,
D.C.
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