Definition: A structure acting as a barrier to hold back water, usually erected as a bank or wall across a free-flowing watercourse such as a stream or river. Dams may be constructed of earth, rocks, logs, or anything else that will create a reservoir; large modern dams are usually constructed almost wholly of concrete reinforced with steel. The purposes of dams include flood control, irrigation, navigation, recreation, and the generation of hydroelectric power. Nearly every major river in the world has at least one dam. Some of the drawbacks of dams include degraded habitat for fish, birds and other wildlife; reductions in water quality; reduced streamflows; and interruption of the natural sediment deposition cycle.
Terms, Definitions, and Concepts: Agriculture, Biology, Conservation and Sustainability, Construction and Building, Ecology, Forestry and Silviculture, Geography, Hydrology, Management, Science, Water
Added: Fri Jan 06 2006
Last Modified: Wed Aug 27 2008