Three Gorges Dam

The Three Gorges Dam, officially known as Yangtze River Three Gorges Water Conservancy Project is a hydroelectric gravity dam that spans the Yangtze River near Sandouping in Yiling District, Yichang, Hubei province, central China, downstream of the Three Gorges. It is also the world's largest power station by installed capacity (22,500 MW); it generates 95±20 TWh of electricity per year on average, depending on the amount of precipitation in the river basin. After the monsoons of 2020, the dam produced nearly 112 TWh in a year, breaking the record of 103 TWh set by the Itaipu Dam in 2016. The dam's body, 185 meters high and 2,309 meters wide, was completed in 2006. The power plant became fully operational in 2012, when the last of the 32 main water turbines in the underground plant began production. The last major component of the project, the ship lift, was completed in 2015. Each of the 32 turbines, considered state-of-the-art at the time of their installation, can generate 700 MW. Combined with two 50 MW generators that power the plant itself, the Three Gorges Dam can generate some 22,500 MW—far more than the next-biggest hydroelectric plant, the 16,000 MW Baihetan Dam, also in China. The dam improves the Yangtze River's shipping capacity and provides flood control, helping to protect millions of people from severe flooding on the Yangtze Plain. Additionally, its hydroelectric power generation has helped fuel China's economic growth. As a result, the Chinese government considers the project a source of national pride and a major social and economic success. However, it is controversial domestically and abroad. Estimates of the number of people displaced by the dam's construction range from 1.13 million to around 1.4 million. Its construction has also inundated ancient and culturally significant sites. In operation, the dam has caused some ecological changes, including an increased risk of landslides.

History

Sun Yat-sen envisioned a large dam across the Yangtze River in The International Development of China (1919). He wrote that a dam capable of generating 30 million horsepower (22 GW) was possible downstream of the Three Gorges. In 1932, the Nationalist government, led by Chiang Kai-shek, began preliminary work on plans in the Three Gorges. In 1939, during the Second Sino-Japanese War, Japanese military forces occupied Yichang and surveyed the area. In 1944, the United States Bureau of Reclamation's head design engineer, John L. Savage, surveyed the area and drew up a dam proposal for a "Yangtze River Project". Some 54 Chinese engineers went to the US for training. The original plans called for the dam to employ a unique method for moving ships: the ships would enter locks at the dam's lower and upper ends and then cranes would move them from each lock to the next. Groups of craft would be lifted together for efficiency. It is not known whether this solution was considered for its water-saving performance or because the engineers thought the difference in height between the river above and below the dam too great for alternative methods. No construction work was performed because of the Nationalists' worsening situation in the Chinese Civil War. After the 1949 Communist Revolution, Mao Zedong supported the project, but began the Gezhouba Dam project nearby first, and economic problems including the Great Leap Forward and the Cultural Revolution slowed progress. After the 1954 Yangtze River Floods, in 1956, Mao wrote "Swimming", a poem about his fascination with a dam on the Yangtze River. In 1958, after the Hundred Flowers Campaign, some engineers who spoke out against the project were imprisoned. During China's emphasis on the Four Modernizations during its early period of Reform and Opening Up, The Communist Party revived plans for the dam and proposed to start construction in 1986. It emphasized the need to develop hydroelectric power. The Chinese People's Political Consultative Conference became a center of opposition to the proposed dam. It convened panels of experts who recommended delaying the project. The National People's Congress approved the dam in 1992: of 2,633 delegates, 1,767 voted in favour, 177 voted against, 664 abstained, and 25 members did not vote, giving the legislation an unusually low 67.75% approval rate. Construction started on December 14, 1994. The dam was expected to be fully operational in 2009, but additional projects, such as the underground power plant with six additional generators, delayed full operation until 2012. The ship lift was completed in 2015. The dam raised the water level in the reservoir to 172.5 m (566 ft) above sea level by 2008 and to the designed maximum level of 175 m (574 ft) by 2010.

Composition and dimensions

Made of concrete and steel, the dam is 2,335 m (2,554 yd; 1.451 mi) long and 185 m (607 ft) above sea level at its top. The project used 27.2 million m3 (35.6 million yd3) of concrete (mainly for the dam wall), used 463,000 tonnes of steel (enough to build 63 Eiffel Towers), and moved about 102.6 million m3 (134.2 million yd3) of earth. The concrete dam wall is 181 m (594 ft) high above the rock basis. When the water level is at its maximum of 175 m (574 ft) above sea level, 110 m (361 ft) higher than the river level downstream, the dam reservoir is on average about 660 km (410 mi) in length and 1.12 km (3,675 ft) in width. It contains 39.3 km3 (31,900,000 acre⋅ft) of water and has a total surface area of 1,045 km2 (403 sq mi). On completion, the reservoir flooded a total area of 632 km2 (156,000 acres) of land, compared to the 1,350 km2 (330,000 acres) of reservoir created by the Itaipu Dam.

… excerpt ends here. Continue reading the full article.