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WATER PowerPoint Presentation

WATER

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WATER

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Presentation Transcript

  1. WATER Supply Use management

  2. Sources of water • Groundwater • Aquifers • wells • Surface water • Rivers • Lakes • Streams • reservoirs

  3. groundwater

  4. Note cone of depression

  5. Zones within a watershed

  6. What does a healthy watershed provide? • Food for people, animals • Drinking water for people animals • Habitat for animals, plants • Temporary habitat for migratory birds • Cleaning air of some contaminants • Cleaning water of contaminants • Transportation • Recreation

  7. What are the major uses of water in the U.S.?

  8. Worldwide water use

  9. 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 Thermoelectric

  10. Irrigation

  11. Main impacts of irrigation • 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

  12. 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 Ogallala aquifer

  13. 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 • e.g. desert cities like LA and Las Vegas

  14. Environmental impacts of dams • Loss of land and cultural resources • Riparian habitat lost • 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)

  15. Three gorges of the Yangtze R.flooding displaced millions of people

  16. 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!

  17. sedimentation

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

  19. Upper Colorado River Basin

  20. Colorado river: California-Arizona border

  21. Colorado River delta, Mexico

  22. Hoover dam

  23. Bonneville dam - WA

  24. Point source vs nonpoint source

  25. 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."

  26. CWA • Passed in 1970 • Point pollution was early emphasis

  27. CWA • Nonpoint source pollution now the big issue

  28. Nonpoint source pollution