Transcript Ground water

Topics for today
Dams
- Geography
– Elwha River Dams
– Glen Canyon Dam
– Colorado Compact (1922)
Ground water Chapter IX pp 260-266
• Importance
• Processes
– Hydraulic gradient
– Permeability
• Ground water pollution
• Ground water surface water interactions
– Gaining Streams
– Loosing streams
• Supply and demand
• Focus study 9-2
• Subsidence
DAMS AN D DAM
REMOVAL
Washington state DAMS
Grand Coulee Dam
Elwha River Dam
Glen Canyon Dam
Colorado Pike Meadow
Reading discussion
“Science and Values in River Restoration
in the Grand Canyon”
Deciding what to do with the Grand
Canyon ecosystem rehabilitated/or not?
25,000 float the Canyon every year
Endemic endangered fish species
Razorback sucker
(Xyrauchen texanus)
Humpback chub
(Gila cypha)
Kanab ambersnail
Willow flycatcher
Rainbow trout
• Colorado Compact, 1922
• Why put all this effort in saving a bunch
of sucker fish?
• How are we restoring for? Fish?
Rafters?
• Table 3
Management approaches
1.
2.
3.
4.
5.
Traditional river management
Naturalized ecosystem
Simulated natural ecosystem
Substantially restored river
Full restored river
Traditional river management
• Accepts the river as a transformed
ecosystem
• Maximizes power revenues
• Ecological integrity is a second value
Naturalized ecosystem
• Blend of the old and the new
• Management with minor flow releases
• Mixture of native and introduced
organisms
Simulated natural ecosystem
• Simulated some pre-dam ecological
processes
• Dan releases that resemble pre dam
conditions
• Aim to restore sand bars and fish
habitat
• Seasonal affect of energy production
Substantially restored river
• Restore pre-dam hydrological variability
(more sediment transport)
• Construction of facilities to transport
sediment from the lake downstream
• Built of structures that allow releases
of water at different temperatures
• Constrains in power production and
water availability to lower basins
Full restored river
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Ambiguous management goal
Removal of flow regulation
Removal of the dam
Eradication of non-native species
No power production
Dilemmas..
• Unvegetated bars versus riparian
vegetation
• Reduction of marsh area ….
• Is lost of biodiversity acceptable to
restore pre-dm conditions?