Water in huge quantities is used every day in households, factories. The consumption of water in oil refineries is 10 times to that of the use of petrol. Dams are arrangement which helps us to supply this water required. It stores the water by trapping it from that of the flowing river. With the construction of a dam, a huge lake is formed where the storage is done and it is called as reservoir. The reservoirs can also help irrigating the farms to the nearby areas. The dam is also used to overcome the excessive supply required in dry periods by storing water in rainy season. Dams also prevent floods. Dams also help the river by avoiding the surging that a sea could have done by intruding with its enormous water and bursting the banks. Some are also used for hydro electric power generation.
The Effect of Dams
They are sometimes a threat to the environment. The reservoir formed in the vally at times floods. Aswan high dam, Egypt was built to control the floods on river Nile, but with change in the natural course of the river the fertility of the surrounding lands was affected badly.
Three Gorges DamThe world’s largest electricity-generating dam is the Three Gorges Dam that spans the Yangtze River, China. The total electric generating capacity of the dam will eventually reaches 22,500 MW. The project produces hyproelectricity, increases the river’s navigation capacity and reduces the potential for floods downstream by providing flood storage space.
Concrete DamsConcrete Dams are of two main different types-gravity and arch dams. Arch dams are tall with curved shells of concrete 3m thick. Because of their arch shaped they are not easy to burst and are hence very strong. The vast weight of gravity dams helps them to avoid bursting of dams.
Embankment DamThey are the biggest type of dams. They are constructed by accumulation of rocks and earth for creating a huge barrier. The core of clay helps to prevent the water from seeping through the centre. The stones on the either side help to protect the flow of water inside. The highest dam in the world is Rogunsky dam, Tajikistan and is around 325m high.
Three Gorges Dam on the Yangtze River, Chain is the biggest dam in the world right now and has the largest power generators.
The Nurek dam in Tajikistan is 300 meters tall and is the highest dam of the world (presently).
There are as many as 48,000 dams over 15m high worldwide, with half of these are in china.
The aggregate storage capacity of all the dams worldwide is about 6,000 km³.
Together China, Turkey, Iran and Japan accounted for 67% of the total number of dams under construction worldwide in 2003.
Dam can fail for a number of reasons, including overtopping caused by floods, acts of sabotage, or structural failure of materials used in dam construction.
The worst dam failure in the United States occurred in 1889 in Johnstown, Pennsylvania. Over 2200 died, with many more left homeless.
Dams present risks but they also provide many benefits, including irrigation, flood control and recreation.
Dams have been identified as a key resource of our national infrastructure that is vulnerable to terrorist attack.
States have the primary responsibility for protecting their populations from dam failure. Of the approximately 79,500 dams in the United States, state governments regulate about 95 percent.
About 11,800 dams are classified as high-hazard potential, meaning that their failure from any means, including a terrorist attack, could result in loss of life, significant property damage, lifeline disruption, and environmental damage.
Three Gorges Dam of China is making the negative effect on Earth’s rotation, as the earth rotate slowly and increasing the length of a day by 0.06 microseconds.