Barriers which are built across flowing water, such as rivers or large streams, are called dams. These barriers help us to utilize the power created by the rapid flow of water for generating hydro-electricity and the water itself for irrigation. When the flow of water is restricted, collecting in a single area, this forms a reservoir. Dams are also built to protect the surrounding areas from being flooded. In nature, dams are also built by beavers, to protect their homes and young ones from dangerous predators.
The highest dam ever built is the Rogun Dam, across the Rover Vakhsh in the southern part of Tajkistan. There were initial problems in building this dam and the project was shelved temporarily. However, later on a partnership was formed with Russia in order to complete the project, accomplished in 1990. This dam is 335 meters high, with a summit length of 660 meters, making it the highest dam in the world today.
The Nurek Dam stands next to Rogun Dam on the Vakhsh River. Located in Central Asia this is the world’s largest rockfill dam and, at a height of 300 meters, is amongst the highest in the world as well. Constructed between 1961 and 1980, it has 9 units generating hydroelectric power. These units were installed between 1972 and 1979.
Construction on the Xiaowan Dam was started in January of 2002, and continues today. This hydroelectric arch dam, on the River Lancang in south west China, is going to be one of the highest dams in the world, coming in third after the Rogun and Nurek dams, with a completed height of 292 meters. It is also going to be the world’s second largest dam in terms of hydroelectric power. The 6 power-generating units will each have a 700 MW capacity.
Built to hold back Lac Des Dix in Switzerland, the Grand Dixence Dam is the highest dam in Europe. It is 4 kilometers long and 285 meters high. When it is full, the depth is of 284 meters and it holds 400 million cubic meters of water. Though the River Dixence is one of the smaller rivers in the area, water collects here in large quantities due to tunnels which bring in water from other sources. The lake is at its maximum depth in September.
A hydroelectric dam, Inguri is in the country of Georgia. With a height of 272 meters, it is amongst the highest dams in the world. The Inguri Power Station is located in Abkhazia with the dam is built on the Inguri River. Construction of this dam began in 1961 however it was competed only in 1987. There are five generators at the Inguri Power Station.
Vajont Dam is 262 meters high. It is located in the Vajont River valley, Italy, about a hundred kilometers to the north of Venice. As attention was not paid to the amount of filling the dam could take, it resulted in a landslide. This wreaked havoc and cost extensive loss of life in the surrounding areas. This is often cited as one of the worst tragedies in the world as the error was manmade.
This 261 meter-high dam is in Grijalva, Mexico. It was completed in 1984 and has a capacity of 1660 cubic meters of water. It also plays host to one of the largest hydroelectric power plants in the world.
Tehri Dam was built close to the town of Garhwal, India, in order to trap the water from the basin of the Upper Ganga, at the Bhilanganga and Bhagirathi confluence. Many people were relocated because of the lake formed by these waters and were forced to find homes in other places. The dam was constructed amidst the ensuing chaos of opposition. This dam is one of world’s highest, with a height of 261 meters.
Construction for the Alvaro Obregon Dam took five years to complete, beginning in 1947. The largest dam in the state, it is built on the river Yaqui. Several main and secondary canals flow from the dam and irrigate the surrounding land. Not only is it important for local irrigation and hydraulic works, it is also a tourist attraction because of the beauty of the surrounding scenery.
Mauvoisin Dam in Switzerland, at 250 meters high, is amongst the highest dams in the world and the third highest arch dam.