Wednesday, September 19, 2012

The Three Gorges Dam

China's Three Gorges Dam became fully operational in July. So far, no ecological catatrophes, although there have been numerous damaging landslides along its lake. The dam is one of the world's largest power stations, with a capacity of 22,500 MW. Other statistics:
Made of concrete and steel, the dam is 2,335 m (7,661 ft) long and the top of the dam is 185 metres (607 ft) above sea level. The project used 27.2 million cubic metres (35.6×106 cu yd) of concrete (mainly for the dam wall), 463,000 tonnes of steel (enough to build 63 Eiffel Towers) and moved about 102.6 million cubic metres (134.2×106 cu yd) of earth.[24] The concrete dam wall is 181 metres (594 ft) high above the rock basis. When the water level is at its maximum of 175 metres (574 ft) above sea level, which is 110 metres (361 ft) higher than the river level downstream, the dam reservoir is on average about 660 kilometres (410 mi) in length and 1.12 kilometres (3,700 ft) in width. It contains 39.3 km3 (31,900,000 acre·ft) of water and has a total surface area of 1,045 square kilometres (403 sq mi).
One thing we don't know yet is how much sediment is being trapped by the dam. If it traps as much as some critics fear, its lake will fill in a few decades, and coastal sediments downstream, including the site of Shanghai, will experience severe erosion.

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