A barrier built, usually across a watercourse, for impounding or diverting the flow of water.
A structure of earth, rock, or concrete designed to form a basin and hold water back to make a pond, lake, or reservoir.
Dams are usually constructed by making a large embankment that blocks an existing watercourse. This embankment is used to control the release of flood waters downstream of the Dam. A structure built across a river to hold back water for a variety of reasons, including protecting areas from floods, storing water for irrigation and domestic use, and generating power.