Three Gorges Dam

Three Gorges Dam is a gravity dam spanning the Yangtze River near the town of Sandouping in Yiling District, Hubei province, central China. It is the world's largest power station in terms of installed capacity and represents a monumental feat of modern Chinese engineering. The project was conceived to control devastating floods on the lower Yangtze basin, generate vast amounts of hydroelectricity, and improve navigation for river transport. Since its completion, it has had profound and controversial impacts on the region's environment, economy, and society.

History and planning

The concept of a major dam on the Yangtze River in the Three Gorges region was first proposed in the early 20th century by Sun Yat-sen in his 1919 work, *The International Development of China*. Serious study began under the Nationalist government in the 1940s, with surveys conducted by the United States Bureau of Reclamation. After the establishment of the People's Republic of China, Mao Zedong enthusiastically endorsed the project, famously penning a poem about "walling off clouds and rain". However, the immense technical challenges, political turmoil during the Cultural Revolution, and significant domestic opposition delayed serious action. The project was finally approved by the National People's Congress in 1992, amid unprecedented debate and a rare number of opposing votes, following decades of feasibility studies and design work led by institutions like the Changjiang Water Resources Commission.

Design and construction

The dam is a concrete gravity dam measuring approximately 2,335 meters in length and 185 meters in height. Its construction required over 28 million cubic meters of concrete and 463,000 tonnes of steel. The project created a massive reservoir, the Three Gorges Reservoir, with a total capacity of 39.3 billion cubic meters. A key feature is the ship lift and a system of five-tier ship locks, allowing vessels to bypass the dam. Construction, managed by the state-owned China Three Gorges Corporation, officially began in 1994. The river was successfully diverted in 1997, and the main wall was completed in 2006. The final turbine generator was installed in 2012, with the entire complex declared fully operational in 2020 after the ship lift passed all tests.

Environmental and ecological impact

The dam's environmental consequences are extensive and widely debated. The reservoir submerged hundreds of factories, mines, and waste dumps, raising concerns about water pollution. It has dramatically altered the river ecosystem, contributing to the decline of species like the Yangtze river dolphin (functionally extinct) and the critically endangered Yangtze finless porpoise. Changes in sediment flow have led to erosion downstream and affected the delta region near Shanghai. There are also ongoing concerns about the risk of landslides along the reservoir banks and the potential for induced seismicity, though monitoring by the China Earthquake Administration has not recorded major seismic events directly attributable to the dam.

Economic and social effects

Economically, the dam provides immense benefits, primarily through flood control for the Jianghan Plain and regions around cities like Wuhan and Nanjing, and through the generation of clean electricity for eastern China, including Shanghai and Guangzhou. The improved navigation conditions have boosted Yangtze shipping, making Chongqing a major inland port. However, these gains came at a tremendous social cost. The reservoir's filling necessitated the relocation of over 1.3 million people from 13 cities, 140 towns, and 1,350 villages, in what is considered the largest peacetime relocation in history. Many displaced persons faced challenges with compensation, employment, and cultural dislocation, with significant criticism directed at local implementation of resettlement policies.

Technical specifications and operations

The dam's hydroelectric power station has a total installed capacity of 22,500 megawatts, generated by 32 main Francis turbine units (each 700 MW) and two smaller 50 MW units for station service. It is operated by China Yangtze Power, a subsidiary of China Three Gorges Corporation. The average annual power generation is approximately 100 terawatt-hours. The dam's flood control capacity is 22.15 billion cubic meters, which is crucial for managing the summer monsoon floods of the Yangtze. Operations are managed from a central control room, coordinating electricity dispatch to the State Grid and managing reservoir levels, ship lock transit, and sediment flushing.

Category:Dams in China Category:Buildings and structures in Hubei Category:Hydroelectric power stations in China