Thursday, November 27, 2008

iMpEriaL daM



IMPERIAL DAM

The Imperial Dam is a dam near Yuma, Arizona (USA), built in the 1930s. It diverts Colorado River water into three different canals and holds the river water until it can be directed into a desilting plant before being released into the All-American Canal, the Gila River, and the Yuma project aqueduct. While it was being built between 1932 and 1940, the Imperial Irrigation District (IID) relied on water from two temporary canals: the Inter-California canal and the Imperial canal (Alamo river).
The dam was built with three sections; the gates of each section hold back the water to help divert the water towards the desilting plant. Three giant desilting basins and seventy-two 770 foot (230 m) long scrapers hold and desilt the water; the removed silt is carried away by six sludge-pipes running under the Colorado River that dump the sediment into the California sluiceway, which returns the silt to the Colorado River. The water is now directed back towards one of the three sections which divert the water into one of the three channels. About 90% of the volume of the Colorado River is diverted into the canals at this local. Diversions can near 40,000 ft³/s (1,100 m³/s), roughly the volume of the Susquehanna River and more than 50 times the natural volume of the Rio Grande River.
The Gila River and the Yuma project aqueduct branch off towards Arizona while the All-American canal branches southwards for 37 miles (60 km) before reaching its headworks on the California border and bends west towards the Imperial Valley.
Though the All-American canal moves billions of gallons of water into Imperial Valley every year, millions of it are lost due to seepage problems. IID and Mexican authorities are debating on whether or not to line the All-American canal with concrete. The Mexican authorities are opposed to the All-American canal lining project, as the leaking water allows Mexican farmers to irrigate their crops with well-water.

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