How do dams work?

Dams stand as one of the earliest inventions of humankind. Aqueducts were built in Rome to control the flow of water. Modern dams show the great ingenuity of human brain and have taken the early concept to a whole new level. Dams help us in power generation, navigation, fishing, flood control, irrigation, water supply, and recreational activities.

Controlling the river

Dams are primarily built to control the flow of water in a river. They are built by erecting thick concrete walls along the bank of a river or sometimes in between to regulate the direction and flow of the water flow. Dams have several gates known as spillways, which need to be ‘open’ for water to pass. Power generating dams have turbines and powerhouses apart from the spillways. Dams can also help in sustaining the ecosystem of the river and the surrounding banks and areas.

The rivers which tend to flood every year have to be controlled by dams. Examples are the Tennessee River in the United States and the Brahmaputra in India.


Dams built primarily for navigation have spillways and locks. Gravitational force is used to fill the lock with water. Water gushes in from the top of the dam and is filled or emptied in the lower quarters of the dam. This regulates the water level. It is possible for the smaller boats to pass through the locks and continue their journey without any danger.


Spillways are kind of gates that allow the water to pass through the dam. When it’s in the ‘open’ state, water can pass through it, and while it is ‘closed’ the flow of river gets restricted. The spillways help in lowering the level of water in the lakes above the dam. This facilitates in controlling the water level of the river and helps the river to maintain its course without spilling over or causing any damage. If the volume of water increases behind the dam, it can be regulated. This ensures that flood control can be promptly done, so that an instance of flood can be avoided. Specifically, the extra water is diverted to other rivers. This also minimizes the chances of flooding.

Power generation

Generation of power is one of the primary purposes of building a dam. While water flows through the gates of the dams, the power of water is used for rotating the turbines, which in turn are connected to the generators, which produce power. The energy needed to rotate the turbine comes from the force with which the river flows. Hydroelectricity is perhaps the most suitable and feasible solution for the energy problem. Since water is a renewable energy, this is also one of the best ways to generate electricity in comparison to the depleting sources of thermal energy such as coal.


Recreational activities and fishing are also facilitated by using the same principles of controlling the water level constant. Irrigation facilitated by the dams is a huge benefit to the economy of the country. When there is a drought condition, water from the dams is routed through channels to the fields, so that the crops and the fields can be well irrigated.

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