What is Dam ?

Capable of producing 87 TWh of electricity per annum, this hydropower dam uses 32x700 MW and 2x50 MW of Francis turbines. Its structural profile is designed with a large base width of 115 m and tapers to 40 m at the crest

French engineer Benoît Fourneyron developed the first successful water turbine in 1832. The era of large dams was initiated after Hoover Dam was completed on the Colorado River near Las Vegas in 1936. By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m (49 ft) high.

This idea goes way back into history. Irrigation is an important part of using water. In areas where water and rain are not abundant (like the desert), irrigation canals from rivers and dams are used to carry water.

Intended not only to produce electricity, the three Gorges Dam was also constructed to increase the shipping capacity of the Yangtze river and mitigate the chances of flooding downstream by providing large water storage space.

Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers. Man-made dams are typically classified according to their size (height), intended purpose or structure.

Dams help in preventing floods. They catch extra water so that it doesn’t run wild downstream. Dam operators can let water out through the dam when needed

The most mind blowing fact about this dam is that it's capable of slowing the Earth's rotation by shifting immense volume of water.

Based on structure and material used, dams are classified as easily created without materials , arch-gravity dams, embankment dams or masonry dams, with several subtypes.

The first upstream flood control dam was built in 1948, Cloud Creek Dam in Oklahoma.

Tarbela Dam (Pakistan)
Considered as the largest earth-filled dam in the world, the Tarbela Dam in Pakistan impounds the Indus river to serve as irrigation supply, flood control, and to produce hydroelectric power.

In the arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction

Since the water stored in dams is fresh water, it can then be used for drinking water in nearby towns and cities. Some cities get their water from rivers and streams in other states. The water is transported through large canals and waterways.

In order to properly divert the Indus river, the dam's construction had to be done in three stages where large tunnels had to be constructed to act as diversion channels.

When the upstream face is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above.

Dams provide a wonderful opportunity for recreation. In building a dam water is stored behind it. This water is called a reservoir. Reservoirs are used to store water, especially during times of excess. They provide activities like fishing, boating, swimming, camping, and hiking.

The dam's main wall was built with earth and rock fill that spans 2,743.2 m from the island to the right-hand side of the river. Two concrete auxiliary dams span the river from the island to the left-hand-side.

For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock.

Rivers and streams provide a great opportunity for transportation. Barges and ships can navigate along a river carrying large loads of food and merchandise. This style of transportation is effective because the loads carried can be quite large.

Equipped with 10x175 MW and 4x432 MW of turbines, Tarbela Dam is capable of producing 14.959 billion kWh of electricity per annum.

The safety of an arch dam is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected.

Almendra Dam (Spain)
One of Spain's tallest structures, the Almendra Dam, literally translates to almond, is located in the country's province of Salamanca. Impounding the Tormes river, this concrete gravity arch dam is part of the hydroelectric system known as the Duero Drops.

Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards the bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones

The Duero Drops system is composed of five dams from Spain and three other dams nearby Portugal. The spillway seen from the photo below can disperse water at a rate of 3,039 cubic meters per second.

Falls Dam, in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept a constant and the variation in distance between the abutments at various levels are taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam is a constant-angle arch dam.

A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments.