10/11/2009 1 Chapter 6 Water Resources Elemental Geosystems 5e Robert W. Christopherson Charles E. Thomsen
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Chapter 6Water Resources
Elemental Geosystems 5e
Robert W. ChristophersonCharles E. Thomsen
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Water ResourcesThe Hydrologic Cycle
Groundwater Resources
Our Water Supply
The Hydrologic CycleA Hydrologic Cycle Model
Surface Water
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Hydrologic Cycle Model
Figure 6.1
Surface Water
Figure 6.2
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Precipitation in North America
Figure 6.4
Types of Soil Moisture
Figure 6.7
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Figure 6. 9
Groundwater ResourcesGroundwater Profile and Movement
Groundwater Utilization
Pollution of Groundwater Resource
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Groundwater Potential
Figure 6.13
Groundwater Characteristics
Figure 6.14
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Groundwater Characteristics
Figure 6.14
Groundwater and Streamflow
Figure 6.16
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Our Water SupplyWater Supply in the United States
Water Supply in California
Water Supply in Los Angeles
Future Considerations
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Water Withdrawal by Sector
Figure 6.18
Global Water Scarcity
Figure 6.20
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• Hot dry summers with periods of d ht
Bsh
California Water Supply
drought
• Winter and early spring rainCsaCsbDE
Bwh
Southern California
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• Surface water, irrigation ditches • Groundwater reserves
Historical Water Supply
• Groundwater reserves
Los Angeles River, Griffith Park, 1900 (USC Digital Archives)Los Angeles River, 1890 (USC Digital Archives)
Imported Water:
• Los Angeles Aqueducts
Water Supply Today
Los Angeles Aqueducts
• Colorado River Aqueduct
• California Aqueduct (San Francisco Bay/Sacramento-San Joaquin Delta)
• Local Sources (groundwater basins)
• Limited amounts of treated wastewater and locally captured surface runoff in some areas
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Los Angeles AqueductsLos Angeles Aqueducts
Water Supply Today
• Built in 1913
• 340 miles from the Mono Basin through Owens Valley to Los Angeles
• Water is conveyed by gravity alone
• There are seven reservoirs in the system with a combined storagesystem with a combined storage capacity of 300,560 AF.
Photo courtesy of LADWP
Colorado River AqueductColorado River Aqueduct
• Began in 1933, operational in
Water Supply Today
g , p1941
• Covers 242 miles from Lake Havasu to Lake Mathews
• Can deliver up to 1.3 million acre feet per year
• There are 9 reservoirs with a storage capacity of 1 092 000
Metropolitan Water District of Southern California
storage capacity of 1, 092, 000 AF.
• 775 miles of pipeline
California Farm Water Coalition
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California AqueductCalifornia Aqueduct
C l t d i th 1970’ t
Water Supply Today
• Completed in the 1970’s to bring water to the San Fernando Valley
• Begins at Lake Oroville ends in Los Angeles County
• Includes 21 lakes and reservoirs, 661 miles of pipeline
Photo by William Selby
• Average total energy generated annually 7.6 billion Kilowatt hours
(c) 2004 Andrew Alden
Metropolitan Water DistrictMetropolitan Water District
Water Supply Today
• Public agency formed in 1928 by a vote of electorates from 13 Southern California cities.
• 26 member cities and water districts that provide water to 18 million people
• Goal is to provide adequate and reliable supplies of drinkingreliable supplies of drinking water to it’s service area.
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Water Supply Today
One acre/foot of water serves the needs of five Los Angeles residents
Between 2000 and 2003 Los Angeles County gained 500,000 new residents (Public Policy Institute of California)
In 2003 MWD sold 2 368 999In 2003 MWD sold 2,368,999 acre feet of fresh water, or approximately 772 billiongallons (MWD)
• LADWP sells approx 660,000
City of Los AngelesCity of Los Angeles
Water Supply Today
pp ,acre/feet of fresh water each year. One Acre/foot is about 326,000 gallons (215,160,000,000 gallons)
• On average, the city has imported about 65% of it’s water from the Los Angeles Aqueduct, 15% from local groundwater reserves, and 20%
Figures from the Los Angeles Department of Water and Power (2005)
from MWD.
• Keep in mind every city has slightly different demands and dependencies.
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The creation of dams and alteration of natural hydrology has had a tremendous environmental impact.
Water Supply Today
• Alteration of natural hydrological processes (ex. Groundwater recharge, stream flow, etc.)
• Alteration of vegetation along riverbed
• Increased use of irrigation in places where there was previously no need
• The depletion of riverbed gravels reduces habitat for many fish that spawn in the gravelly river bottom, and for invertebrates such as insects, mollusks and crustaceans
• Decline in fish abundance and diversity
• Increase in invasive species
• Decline in habitat available for migratory bird species
GroundwaterGroundwater
Water Supply Today
Water found subsurface stored in:
Aquifers (confined or unconfined)
Permeable rock layers
Unconsolidated Sediments
Soil moisture
• San Fernando Valley
Groundwater found 6 - 57 meters below the surface
Great variability, however all measurements are trending to an increasing depth to groundwater
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ProblemsProblems
Water Supply Today
• Subsidence
• Water and oil extraction from compressible sedimentary layers
• SFV - subsidence occurring 6 -80mm per year
• Salt water intrusion (not a SFV issue)
• Lowered water tables
• Sea level rise
• Pollution