The design of a concrete dam depends largely on the purpose of the dam, as well as the configuration of the site on which it will be built. There are two primary types of dams, overflow dams and non-overflow.
Overflow dams block the flow of a stream and harness the water for power generation, they are also often used to improve navigation and provide irrigation water. An overflow dam is designed so that water can be released, allowing the level of water in the reservoir to be regulated by a series of sluice gates, spillways and outlet tunnels.
Non-overflow dams are mainly used to tore water for drinking water supply, irrigation, or power; they also have a spillway, but its use is restricted for emergencies to lower the water level quickly during floods. The methods for releasing stored water in non-overflow dams are limited when compared to overflow as this design does not contain any outlet structures. However, water may be sometimes be pumped out for irrigation or other uses.