The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in Yiling District, Yichang, Hubei province, China. The Three Gorges Dam is the world’s largest power station in terms of installed capacity (22,500 MW) but is second to Itaipu Dam with regard to the generation of electricity annually.
Except for a ship lift, the dam project was completed and fully functional as of July 4, 2012,when the last of the mainturbines in the underground plant began production. Each main turbine has a capacity of 700 MW. The dam body was completed in 2006. Coupling the dam’s 32 main turbines with two smaller generators (50 MW each) to power the plant itself, the total electric generating capacity of the dam is 22,500 MW.
As well as producing electricity, the dam is intended to increase the Yangtze River’s shipping capacity and reduce the potential for floods downstream by providing flood storage space. The Chinese government regards the project as a historic engineering, social and economic success, with the design of state-of-the-art large turbines, and a move toward limitinggreenhouse gas emissions. However, the dam flooded archaeological and cultural sites and displaced some 1.3 million people, and is causing significant ecological changes, including an increased risk of landslides. The dam has been a controversial topic both domestically and abroad.
COMPOSITION AND DIMENSION
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. 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). On completion, the reservoir flooded a total area of 632 square kilometres (244 sq mi) of land, compared to the 1,350 square kilometres (520 sq mi) of reservoir created by the Itaipu Dam.