What is Dam ?

the height of the dam will depend upon the strength of the foundation material.

Located on the Euphrates river, the Atatürk Dam is the largest in Turkey and ranks sixth from the largest earth-and-rock filled embankment dams in the world. It is the centerpiece of the 22 dams that exist on the Euphrates and the Tigris, which comprise the integrated sectors of the Southeastern Anatolia Project, or GAP in Turkish (Güney Doğu Anadolu Projesi).

It is also easy to understand that the easiest direction for slippage in stratified rocks is along the bedding planes. Consequently, the most UNFAVOURABLE strike direction is the one in which the beds strike parallel to the axis of the dam and the dip is downstream (Fig. 23.5.B). It must be avoided as far as possible. Therefore, other conditions being same, beds with upstream dips are quite favourable sites for dam foundations.

A dam is a barrier that stops or restricts the flow of water or underground streams

In 1975, the Banqiao Dam in China was among many dams that were destroyed after the extreme rains of Typhoon Nina. It is estimated that between 90000 and 230000 lives were lost as a result of the Banqiao Dam breaking.

A rockfill dam is built of rock fragments and boulders of large size. An impervious membrane is placed on the rockfill on the upstream side to reduce the seepage through the dam

The Atatürk reservoir has a capacity of 48.7 cubic kilometers of water and equipped with 8x300 MW Francis turbines, which generate 8,900 GWh of electrical power per annum. The construction of the dam wiped out many important historical sites like the birthplace of the Ancient Greek poet Lucian.

Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability.

Different types of rocks may be present on either side of a fault plane. Hence, sites with fault planes require great caution in calculating the design strength in various sections of the dam. In case some fault surface or zone gets ignored or overlooked, the stability of dam gets endangered.

The membrane is usually made of cement concrete or asphaltic concrete. In early rockfill dams, steel and timber membrane were also used, but now they are obsolete.

About 50,000 dams with a height of 15 meters or more and millions of smaller dams have been built on the world’s rivers.

Hydropower is often used in conjunction with dams to generate electricity.

One of the largest in Africa, the Kariba Dam supplies 1,626 MW of power to the Copperbelt parts of both Zambia and Zimbabwe. Impounding the Zambezi river, Kariba dam is outfitted with 10 types of Francis turbines capable of outputting an average of 6,400 GWh of electrical power per year.

The membrane is usually made of cement concrete or asphaltic concrete. In early rockfill dams, steel and timber membrane were also used, but now they are obsolete.

Dams founded on beds traversed by fault zones and on major fault planes are more liable to shocks during an earthquake compared to dams on non-faulted rocks. This single factor in itself is of great importance, especially when the area in which dam is proposed happens to be seismically active. It is, therefore, always desirable to avoid risk by rejecting sites traversed by faults, fault zones and shear zones for dam foundations

The dam was designed as a double curvature concrete arch dam to effectively resist the 180 cubic kilometres of water pressing against it.

Some of them date back centuries, but most were built after World War II. About 5,000 dams have a height of 60 meters or more; another 350 such giants are currently under construction.

A dry rubble cushion is placed between the rockfill and the membrane for the distribution of water load and for providing a support to the membrane.

A dam can also be used to collect water or for storage of water which can be evenly distributed between locations.

topographic, lithological and/or economic factors do not leave a choice for an alternative site, then the nature, extent and age of the fault should be thoroughly investigated. Generally small scale fault zones and shear zones can be treated effectively by grouting. But in the case of major shear zones, weak material would have to be excavated and the space backfilled with hard material like concrete up to the required depth.

the rockfill dams have an impervious earth core in the middle to check the seepage instead of an impervious upstream membrane

Dams have fragmented two thirds of the world’s large rivers and flooded a land area the size of California. Their reservoirs contain three times as much water as all the world’s rivers, and constantly lose close to four Niagara Falls to evaporation.

The most notable effects of folds on rocks are – shattering and jointing along the axial planes and stressing of limbs. Consequently, dams aligned along axial regions of folds would be resting on most unsound rocks in terms of strength. Similarly, in synclinal bends dams placed on the upstream limbs would run the risk of leakage from beneath the dam. Further, the balance of forces in the stressed limbs would be disturbed if these are opened up during construction of diversion tunnels and galleries.

Designed for producing hydroelectricity, the Kerr Dam also serves as wildlife resources, forest conservation, and public recreational uses. By impounding the Flathead River, the dam is capable of producing 426 GWh of electricity per annum. It is one of the two PPL Montana dams located west of the Continental Divide where the Flathead river cascadingly empties into the Clark Fork River, which subsequently empties into the Columbia River. Finally, the Columbia River empties right into the Pacific ocean.

Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions.