A dam is a man made barrier usually built across a river to hold back water and forming a lake, or reservoir, behind it. It can be constructed from concrete or natural materials like earth and rock. A dam is a hydraulic structure of fairly impervious material built across a river to create a reservoir on its upstream side for impounding water for various purposes. These purposes may be Irrigation, Hydro-power, Water-supply, Flood Control, Navigation, Fishing and Recreation. Dams may be built to meet the one of the above purposes or they may be constructed fulfilling more than one
Types:
Arch Dam
Arch dams are made from concrete. They are curved in the shape of an arch, with the top of the arch pointing back into the water. An arch is a strong shape for resisting the pushing force of the water behind the dam. Arch dams are usually constructed in narrow, steep sided valleys. They need good rock for their foundations, and for the sides of the valleys, to resist the forces on the dam. There are only a few arch dams in the UK, including Monar Dam in Scotland.
Buttress Dam
A dam consisting of a watertight part supported at intervals on the downstream side by a series of buttresses. A buttress dam can take many forms, such as a flat slab or a massive head buttress. Ambursen dam. A buttress dam in which the upstream part is a relatively thin flat slab usually made of reinforced concrete. Multiple arch dam. A buttress dam composed of a series of arches for the upstream face.
Coffer Dam
A temporary structure enclosing all or part of the construction area so that construction can proceed in the dry. A diversion cofferdam diverts a stream into a pipe, channel, tunnel, or other watercourse.
Gravity Dam
A Gravity dam is a structure which resists the external forces by its own weight or self-weight. Gravity dams are generally constructed by using masonry or concrete. Various external forces like water pressure, uplift pressure, wave pressure, ice pressure, earth quake pressure etc. are resisted by its self-weight only which acts vertically downwards. So, good foundation is required to construct gravity dam preferably rocky strata under the dam. The shape of cross section of gravity dam is approximately triangular in shape. Infiltration gallery can be provided within the dam to resist uplift pressure. The failure of gravity dam may occurs due to sliding, overturning or crushing at toe. Hence, higher factor of safety is recommended for the design of gravity dam.
Storage Dam
Storage dam is constructed to store water on the upstream side especially during rainy seasons and is released during dry weather season or when there is higher demand of water. The stored water can also be used to generate power, irrigation, water supply etc.
Diversion Dam
Diversion dam is a dam which is constructed to divert the flow of water into other channel or canal. This type dams are generally used to fill the irrigation channels.
Hydro-power Dam
Hydro-power dam is used to generate electricity by rotating turbines with the help of water falling from upstream side to downstream side of dam.
