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WATER

WATER. Supply Use management. What are the major uses of water in the U.S.?. As of 2000: Making electricity 48% (thermoelectric) Irrigation 34% Public supply 11% Industrial 5% Domestic <1% Aquaculture <1% Mining <1% Livestock <1%. Worldwide water use.

jakeem-goodman
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WATER

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  1. WATER Supply Use management

  2. What are the major uses of water in the U.S.? • As of 2000: • Making electricity 48% • (thermoelectric) • Irrigation 34% • Public supply 11% • Industrial 5% • Domestic <1% • Aquaculture <1% • Mining <1% • Livestock <1%

  3. Worldwide water use

  4. Thermoelectric • Burning fossil fuels to make electricity. • Boils water to turn generator • Uses lots of water to condense the boiled water • Much water lost to evaporation (consumptive) • Still, much of the use is non-consumptive • Water used in the plant is returned downstream

  5. Irrigation

  6. Main impacts of irrigation • Dams • Waterlogging of soil • Salinization • Overdraft of groundwater • Main source of drinking water for ½ the US • If withdrawal > replenishment  mining • Irrigation is mainly consumptive—water evaporates or transpirates and doesn’t return to source

  7. Ogallala aquifer • HUGE: water-bearing sands, gravels under about 400,000 km2 from SD to TX • Use in some places is 20 times greater than rate of replenishment

  8. Why are dams built? • Usually, many advantages cited. WHY? • Appeal to as many constituents as possible • Diversion of water for irrigation • Flood control • Recreation • Stable water supply

  9. Environmental impacts of dams • Loss of land and cultural resources • Sediment trapped behind dam. Why bad? • Reservoir fills up, reducing its life • Sediment would supply sand and nutrients • River below dam is unnatural (flows irregular)

  10. Three gorges of the Yangtze R.

  11. Flooding of three gorges dam • Rains in upper Yangtze basin so great the reservoir filled, threatening dam and towns. • Releases of water so great that downstream towns threatened.

  12. Dams destroy riparian habitat

  13. Sedimentation problems with dams • Problem that faces all dams • Many trap nearly 100% of the sediment that washes down a river. • As sediment accumulates, reservoir can hold less water • but that was the point of the dam in the first place—to hold water!

  14. What happens to rivers? • Colorado River near its source in Rocky Mt. Nat. Park.

  15. Hoover dam

  16. Clean Water Act • Addresses surface water quality • Not directly groundwater or quantity • Tools to reduce pollutant discharges into waterways for "the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water."

  17. CWA • Passed in 1972 • Point pollution was early emphasis

  18. CWA • Nonpoint source pollution now the big issue

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