Dams and barrages are barriers constructed across a river or a natural water course for diverting water into a canal for the purpose of irrigation or water supply, or into a channel or tunnel for generation of electricity. However, despite their similarities, there are differences in these two structures that will be discussed in this article for the help of those who remain confused between a dam and a barrage.
Apart from differences in their functions, there are physical differences between dams and barrages also. In case of barrage, the entire length across a river that is between the banks is provided with gates having their bottom level touching the river bed level. This implies that the water stored behind a barrage is totally dependent upon the height of its gates. On the other hand, in the case of a dam, there are spillway gates near its top level and the storage of water behind the dam is mainly due to the height of the concrete structure and partially due to the height of the gate. However, care is taken both in the case of dams as well as barrages to keep the number and size of gates adequate to account for floods in monsoons.
A barrage is considered as a type of dam consisting of a series of large gates that can be closed or opened to have a control on the amount of water passing through it. These gates are primarily meant for controlling the flow of water and to stabilize the flow of water for irrigation purposes. One key difference between a dam and a barrage according to World Commission on Dams is that while a barrage is built for diverting water, a dam is built for storing water in a reservoir to raise the level of water considerably. A barrage is usually built where the surface is flat across meandering rivers. It raises the water level only by a few feet.
It has to be kept in mind that both dams and barrages make use of surplus water and the normal flow of water through the river. The river continues to flow normally as before. A dam stores surplus flood water and distributes it through irrigation tunnels in the dam or through canals from its reservoir. In the case of barrages, there is no such storage and the canals take water directly from the rivers. Thus it can be said that whereas dams add water, barrages subtract it.
Dam vs Barrage
• Dams are artificial barriers across a flowing river or any other natural water body that are meant to obstruct, direct, or slow down the flow of water, thus creating a reservoir or a lake.
• A barrage is an artificial obstruction at the mouth of a river that is used to increase its depth to assist in navigation or for irrigation purposes.