Monday, October 22, 2012

Hydro Dams

It’s easier to build a hydropower plant where there is a natural waterfall. That’s why both U.S. and Canada have hydropower plants at Niagara Falls. Dams, which are artificial waterfalls, are the next best way.

Dams are built on rivers where the terrain will produce an artificial lake or reservoir above the dam. Today there are about 84,000 dams in the United States, but less than three percent (2,200) have power-generating hydro plants. Most dams are built for flood control and irrigation, not electric power generation.

A dam serves two purposes at a hydropower plant. First, a dam increases the head, or height, of the water. Second, it controls the flow of water. Dams release water when it is needed for electricity production. Special gates called spillway gates release excess water from the reservoir during heavy rainfalls.

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