Dam, structure built across a stream, a river, or an estuary to retain water. Dams are built to provide water for human consumption, for irrigating arid and semiarid lands, or for use in industrial processes. While constructing dams the base is made more wider because a lot of water inside the dam increases the pressure on the ground and if the base will be little bit thinner than the dam can be broken or damaged and may result to a massive flood therefore the dam's bases made wilder.