What is a dam?
Dams are massive barriers built across rivers and streams to confine and utilize the flow of water. This barrier creates a lake, reservoir or an impoundment. Dams are used for human purposes such as irrigation and generation of hydroelectricity.
The first known dam was built in 2900 B.C. across the Nile River to protect the city of Memphis from flooding. Dam build was continued into the time of the Roman Empire, after which dam construction was literally lost until the 1800s. Dams are a structure also seen in nature – beavers build dams to keep the water deep enough to cover the openings to their homes, protecting them from predators.
Jawaharlal Nehru declared dams as the “Temples of modern India”. Some of the important Indian dams are –
Reasons to build a dam:
Generation of hydroelectricity
Irrigation. These are often diversion dams, which stop a river’s natural course so that water can be sent off to a different place.
Control flooding. These are called detention dams, which are constructed to either stop or slow the amount of water in a river.