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Controlling Rivers

Controlling Rivers. Niagra Falls. http://www.youtube.com/watch?v=IyBtnUZESk0. R eport of the W orld C ommis s ion on D ams. www.dams.org. Purposes of large dams. Hydropower Irrigation Water supply Flood control Multipurpose. Irrigation : The Aral Sea.

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Controlling Rivers

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  1. Controlling Rivers

  2. Niagra Falls

  3. http://www.youtube.com/watch?v=IyBtnUZESk0

  4. Report of the World Commission on Dams www.dams.org

  5. Purposes of large dams Hydropower Irrigation Water supply Flood control Multipurpose

  6. Irrigation: The Aral Sea • Once the 4th largest inland body of water in the world A series of dams was built to irrigate cotton. • Aral Sea reduced to about 25% of its 1960 volume, quadrupled the salinity of the lake and wiped out the fishery. Pollutants became airborne as dust, causing significant local health problems. • The environmental damage caused has been estimated at $1.25 -$2.5 billion a year.

  7. Dam Drawbacks to Human Communities Human Displacement Flooding of Cultural Sites (Archeological and Modern) Cost overruns

  8. Dam Drawbacks to the Environment Ecosystem Destruction Fish Blockage and Wildlife Losses Large-Scale Flooding Due to Dam Failures Sedimentation and Salinity Herbicide and Other Toxic Contamination Evaporative Losses Nutrient Flow Retardation Release of greenhouse gasses

  9. Significant U.S. contribution… • 19 percent of electricity from hydropower–more than 50% in 63 countries • dams support 30-40% of irrigated area & 12-16% of global food production • 12% of all dams have a water supply function • 75 countries have dams for flood control Dams and Development - Report of the World Commission on Dams

  10. Gravity Dams

  11. GRAVITY DAMS Gravity dams are dams which resist the horizontal thrust of the water entirely by their own weight. They use their weight to hold back the water in the reservoir. Can be made of earth or rock fill or concrete.

  12. Arch Dam

  13. ARCH DAMS Curved dam which is dependent upon arch action for its strength. Transmits most of horizontal water thrust behind them to the abutments by the arch action. Thinner and requires less material than any other type of dam. Used only in narrow canyons.

  14. Buttress Dams

  15. BUTTRESS DAMS Buttress dams are dams in which the face is held up by a series of supports. Buttress dams can take many forms -- the face may be flat or curved. Usually, buttress dams are made of concrete and may be reinforced with steel bars.

  16. Embankment Dams

  17. EMBANKMENT DAMS Embankment dams are massive dams made of earth or rock. They rely on their weight to resist the flow of water, just like concrete gravity dams.

  18. Components Face Abutments Crest Toe Outlet spillway Upriver (reservoir)‏

  19. Components Face – exposed surface of the structure Abutments – sides of the dam Crest – top of the dam Toe – natural ground surface Outlet – primary opening to discharge water Spillway – chute to allow excess water flow

  20. Crest Down stream Upstream Spillway (inside dam) MWL Max. level NWL Normal water level Free board Sluice way Gallery Heel Toe

  21. Hoover Dam (Boulder Canyon Dam)‏ ConcreteGravity Arch Completed 1935 $175 million Black Creek Canyon Border of Arizona and Nevada

  22. Hoover Dam 726 feet high 1244 ft length 660 feet thick at base 45 feet thick at crest Crest Base Concrete: 4.5 million yds3 Labor: 5,000 men Curing: trapezoidal columns

  23. The Reservoir 10.5 trillion gallons 581 feet deep 110 miles long Lake Mead 2000 megawatts 1 million people/day Irrigation Municipal water Recreation Hydroelectric power

  24. Hoover Dam: 180 m drop to turbine Water flowing from Lake Mead through the gradually-narrowing penstocks to the powerhouse reaches a speed of about 85 miles per hour (137 km/h) by the time it reaches the turbines.

  25. Utah Nevada N.M California Arizona Six major dams Colorado River California Arizona Colorado Nevada Utah Wyoming New Mexico Mexico Gradient 9,000 ft = 6.2 ft/mi 1,450 mi Diversion/allocation 17.5 million acre-feet

  26. Grand Cooley Dam Concrete Gravity Dam Columbia River in Central Washington Constructed 1933-1941

  27. Grand Cooley Dam Largest concrete Structure in the U.S. There is enough concrete in the Dam to build a highway across the United States. Cooling pipes largest single producer of electricity in the United States Roosevelt Reservoir 550 feet high 5223 feet long 500 feet wide at base 30 feet wide at crest 130 square miles.

  28. Kingsley Dam Largest Earthen Dam Ogallala Nebraska North Platte River Constructed 1936-41

  29. Kingsley Dam Width = 3.5 miles Height = 162 feet Base thickness = 1100 feet Crest thickness = 28 feet Steel and Clay core Sand, gravel, soil Lake McConaughy Irrigation Electricity Recreation Habitat 22 miles (35 km) long

  30. Dates Hoover Dam 1931-1935 Grand Cooley Dam 1933-1941 1936-1941 Kingsley Dam Why?

  31. The Great Depression 1929 - 1941 • Over 25% unemployment • Manufacturing down 50% United States Bureau of Reclamation

  32. Concrete Gravity Length = 1.2 miles Height = 608 ft The Three Gorges Dam Yangtze River (The largest dam)

  33. Yangtze River Watershed Houses 1/3 China’s population Supplies ½ China’s food

  34. The Reservoir 574 feet deep 373 miles long Equal in length to Lake Superior

  35. Benefits Hydroelectric Power 8.4 million kilowatts per year 10% of future energy needs Clean energy alternative Flood Protection 300,000 recorded deaths by flooding Navigation Commercial shipping to central China

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