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August 9, 2009

Spectacular Dams Around the World

Posted by : admin
Filed under : General Green
The sight of a dam – one of the largest and most complex structures that humanity has ever created – can be quite breath-taking. Take a look at some of the most spectacular of these structures.

The Hoover Dam – USA


Hoover Dam, originally known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Arizona and Nevada. When completed in 1936, it was both the world’s largest electric-power generating station and the world’s largest concrete structure. It was surpassed in both these respects by the Grand Coulee Dam in 1945. It is currently the world’s 35th-largest hydroelectric generating station.

This dam, located 30 miles (48 km) southeast of Las Vegas, Nevada, is named after Herbert Hoover, who played an instrumental role in its construction, first as the Secretary of Commerce and then later as the President of the United States. Construction began in 1931 and was completed in 1936, more than two years ahead of schedule. The dam and the power plant are operated by the Bureau of Reclamation of the U.S. Department of the Interior. Listed on the National Register of Historic Places in 1981, Hoover Dam was designated a National Historic Landmark in 1985.

Lake Mead is the reservoir created behind the dam, named after Elwood Mead, who oversaw the construction of the dam.

Grande Dixence – Switzerland

The Grande Dixence dam, at the head of the Val d’Hérens in the canton of Valais in Switzerland, is at 285 metres (935 ft) high one of the world’s tallest dams and the highest in Europe. It holds back a lake, the Lac des Dix, around 4 km (2.5 mi) long. When full, the lake is up to 284 metres (932 ft) deep and contains 400 million m³ (100 billion gal) of water.

The top of the dam is at an altitude of 2,365 metres (7,759 ft) in a steep mountain valley. Tunnels bring the water to three power stations in the Rhône valley over 1,800 metres (5,900 ft) below.

The dam is situated on the relatively small Dixence river, but collects a large amount of water thanks to a system of water supply tunnels over 100 km (60 mi) long bringing water from other rivers and valleys. Most of the water comes from glaciers which melt during the summer. The lake is usually full of water by late September, and is allowed to empty during the winter, reaching its lowest point around April.

The first Grande Dixence Dam was constructed between 1929 and 1935. A second dam that would flood the first was built between 1951 and 1965, and was filled on July 17, 1957. The first dam can still be seen when the water level is particularly low.

From 1993 to 1998 a high-pressure pipeline was built to considerably increase its peak capacity. It transported water 1,800 metres (5,900 ft) down to an additional power facility. The pipeline was welded using a new type of steel; it is out of service since it burst in December 2000, with the flood wave killing three people. Work on a replacement pipeline has recently started, with use of a more common steel and additional safety measures.

The Karun Dam – Iran

The Karun-3 dam is a hydroelectric dam on the Karun river in the province of Khuzestan, Iran. It was built to meet Iran’s energy demands as well as to provide flood control. The Karun has the highest discharge of Iran’s rivers. The objectives of the construction of Karun III Dam & Hydro-electric Power Plant are electric Power supply and flood control. Karun III power generators are connected to the National Power network as the Peak Power generation. With this power plant being operated, with the capacity of 2000 MW, and an average electric power generation of 4137 GWh/y, a major portion of the electric power shortage in the country will be met.

Dworshak Dam – USA

Dworshak Dam is a hydroelectric, concrete gravity dam in Clearwater County, Idaho, on the North Fork of the Clearwater River. The dam is located 4 miles (6 km) northwest of the city of Orofino, and 47 miles (76 km) east of Lewiston.

Originally, its name was slated to be “Bruces Eddy,” but was changed to honor Henry C. Dworshak, a U.S. Senator from Idaho from 1946-62. The dam is the highest straight-axis concrete dam in the Western Hemisphere and the 22nd highest dam in the world. Only two other dams in the U.S. exceed it in height.

Construction began in June 1966; the main structure was completed in 1972, with the generators coming online in 1973. Electrical generating capacity is 400 megawatts, with an overload capacity of 460 MW. There are two spillway gates.

Dworshak Dam is part of the Columbia River Basin system of dams. Dworshak Reservoir is formed behind the dam. The reservoir stretches 53 miles (85 km) upstream. The North Fork of the Clearwater River runs 2 miles (3 km) downstream from the base of the dam, where it joins the main Clearwater, which flows into the Snake River at Lewiston, and into the Columbia at Wallula, Washington.

The Inguri Dam – Georgia

The Inguri Dam is a hydroelectric dam on the Inguri River in Georgia. Currently it is the world’s highest concrete arch dam with a height of 272 metres (890 ft). It is located north of the town Jvari. It is part of the Inguri hydroelectric power station (HES) which is partially located in the partially recognised Abkhazia.

Nagarjuna Sagar Dam – India

Nagarjuna Sagar Dam is a masonry dam built across Krishna River in Nagarjuna Sagar, Andhra Pradesh, India. It is Andhra Pradesh’s tallest masonry dam, at a height of 124 metres, and creates a reservoir holding up to 11, 472 million cubic metres.

It is one of the earliest irrigation and hydro-electric projects in India. The dam provides irrigation water to the Nalgonda District, Prakasam District, Khammam District, and Guntur District.

Srisailam Dam

Srisailam Dam is a dam constructed across the Krishna River at Srisailam in the Kurnool district in the state of Andhra Pradesh in India and is one of the 12 largest hydroelectric projects in the country.

The dam was constructed in a deep gorge in the Nallamala hills, 300 m (980 ft) above sea level. It is 512 m (1,680 ft) long, 240.79 m (790.0 ft) high and has 12 radial crest gates. Srisailam Dam provides irrigation water for about 800 km2 (310 sq mi) in Kurnool District and Cuddapah District, which are in the drought-prone Rayalaseema region. Special permission is needed to go on to the main dam.

Glen Canyon – USA

Glen Canyon Dam is a dam on the Colorado River at Page, Arizona, USA, operated by the United States Bureau of Reclamation. The purpose of the dam is to provide water storage for the arid southwestern United States, and to generate electricity for the region’s growing population. The dam generates an average of 451 megawatts, 6% of the total electricity generated in Arizona and 13% of that generated in Utah where most of Lake Powell resides, which amounts to a total carbondioxide savings of over 5 million metric tons, although it has a maximum capacity of 1300 megawatts. Damming the river flooded Glen Canyon and created a large reservoir called Lake Powell. Just downstream from the dam is an arch bridge that carries U.S. Route 89. Also nearby is the 2280 megawatt, coal-fired Navajo Generating Station.

Vajont – Italy

The Vajont Dam is a dam completed in 1959 in the valley of the Vajont river under Monte Toc, 100 km north of Venice, Italy. It was one of the highest dams in the world measuring 262 metres (860 ft) high, 27 metres (89 ft) thick at the base and 3.4 metres (11 ft) at the top.

Its 1963 overtopping during initial filling was caused by the lack of consideration by the designers for the geological instability of the mountain on the southern side of the basin. Warning signs and negative appraisals during the early stages of the filling were ignored; the attempt to complete the filling led to a rapid landslide, causing a seiche wave which brought massive flooding and destruction to the area below, wiping several villages away completely and killing 2,000 people.

On 12 February 2008, while launching the International Year of Planet Earth, UNESCO cited the Vajont Dam tragedy as one of the five worst man-made disasters, caused by “the failure of engineers and geologists.”

Sayano-Shushenskaya – Russia


Sayano-Shushenskaya hydroelectric station is located on the Yenisei river near Sayanogorsk in Khakassia.

As of 2007, it is the largest power plant in Russia and 4th world largest ( by average power generation ) hydroelectric plant. It was opened in 1978. Its installed capacity is 6,400 MW, average annual production is 23,500 GWh, peaked in 2006 with 26,800 GWh. Station constructions include dam, power plant building located near dam, and an additional spillway under construction. The gravity arch type dam is 245 m high, has crest length of 1066 m, crest width of 25 m, base width of 110 m and maximum head of 220 m. The dam consist of solid left-bank dam 246.1 m long, power dam 331.8 m long, spillway dam 189.6 m long and solid right-bank dam 298.5 m long. It is the only gravity-arch dam in Russia of that size, the only other gravity-arch dam is much smaller.

Currently it operates 10 hydro turbines, each with capacity of 640 MW at 194 m head.

The dam forms Sayano-Shushenskoe Reservoir with total capacity of 31.34 km³ and useful capacity of 15.34 km³ and surface area of 621 km².

Almendra Dam – Spain

The Almendra Dam in Salamanca, Spain, interrupts the course of the River Tormes five kilometres from the village from which it takes its name: Almendra (literally, almond). It was constructed between 1964 and 1970.

The dam forms part of the hydroelectric system known as the Duero Drops, along with the Castro, Ricobayo, Suacelle and Villalcampo dams of Spain, and the Bemposta, Miranda and Picote dams of nearby Portugal.

The reservoir that backs up behind the dam covers 86.5 square kilometres and contains 2.5 billion cubic metres of water as well as several drowned villages, among them Argusinos. The dam is more than half a kilometre wide and, at a height of 202 metres, one of Spain’s tallest structures.

Itaipu – Brazil

Itaipu is a hydroelectric dam on the Paraná River located on the border between Brazil and Paraguay.

The name “Itaipu” was taken from an isle that existed near the construction site. In the Guarani language, Itaipu means “the sound of a stone”. The American composer Philip Glass has also written a symphonic cantata named Itaipu in honour of the structure.

Itaipu Binacional is a company that runs the longest operational hydroelectric power plant in the world. It is second only to the Three Gorges Dam in generating capacity. It is a binational undertaking run by Brazil and Paraguay at the Paraná River on the border section between the two countries, 15 km north of the Friendship Bridge. The project ranges from Foz do Iguaçu, in Brazil, and Ciudad del Este in Paraguay, in the south to Guaíra and Salto del Guaíra in the north. The installed generation capacity of the plant is 14 GW, with 20 generating units of 700 MW each. In the year 2008, it achieved its generating record of 94.68 billion kilowatt-hours (kWh), which supplied 90% of the energy consumed by Paraguay or 19% of that consumed by Brazil.

Three Gorges Dam – China

The Three Gorges Dam in Sandouping, Yichang, Hubei, China. It is the largest hydroelectric power station in the world.

With a long history of planning and more than a decade of construction, the dam body was finished in 2006. When the whole project is completed, it will contain 32 main generators, each with a capacity of 700 MW. Except for a planned ship lift, all of the originally planned components of the project were completed on October 30, 2008, when the 26th generator was brought into commercial operation. Six additional generators in the underground power plant are being installed, not expected to become fully operational until around 2011. The total electric generating capacity of the dam will then reach 22,500 MW.

The project produces hydroelectricity (which produces less carbon emissions than most conventional power sources), reduces the potential for deadly floods downstream by providing flood storage space, and enhances navigation by a means of ship locks and a ship elevator. As of April 2009, the dam has generated 300 TWh of electricity, covering 30% its project cost according to Xinhua. The project management and the Chinese state media regard the project as a historic engineering, social, and economic success, a breakthrough in the design of large turbines, and a move towards reducing greenhouse gas emissions. However, the dam has also flooded archaeological and cultural sites and displaced some 1.24 million people, and is causing dramatic ecological changes, including increasing the risk of landslides. The decision to build the dam has been deeply controversial in China and abroad.

credited to wikipedia

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