The Three Gorges Project on the Yangtze River in China
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The Three Gorges project on the Proceedings of ICE Civil Engineering 144 February 2001 Yangtze river in China Pages 20–28 Paper 12320 R. Freer, FICE Keywords Taming the mighty 6300 km long Yangtze river in south China was never going to be easy. Its history is littered with catastrophic flooding events that have destroyed lives and livelihoods and caused untold economic loss.The proposal to build what will still be the world’s largest flood-control dam at the Three Gorges site in the river’s mid-section was put forward as long ago as 1919.Wars and revolutions delayed the start until 1993 and completion is not now scheduled until 2009.This paper Robert Freer describes the planning and design of the £15 billion project and reports on construction progress to date. It highlights in is a former member of the ICE energy board and the ICE research particular the difficulties experienced in assessing the scheme’s and innovation committee. He has benefits against its costs—not least the need to relocate and re- worked on hydroelectric schemes in skill over one million people. many parts of the world The Three Gorges dam being built on the Yangtze river in southern China (Figs 1 and 2) is being designed to allevi- ate flooding in the industrial and agricultural areas down- stream of the dam as well as to supplement urban water supplies in northern China, including the city of Beijing. The project includes a large hydroelectric power station, the income from which will make a substantial contribu- tion to financing the scheme Fig. 1. Aerial view looking west of the Three Gorges flood- control dam under construction in its later stages. Initial Beijing CHINA Quinghai r G r e a Proposed iv n Yellow R d C Yellow diversion a n a Sea Zhengzhou l Han River Dan Jiang Kou dam TGP dam site Tibet Daba S Daning River han autonomous Wuhan SShanghaihanghai region Yichang Chongqing Himalayas r ive East ze R ngt China Ya Sea Talpel Taiwan Hong Kong South China 0 km 500 Sea Fig. 2. Location of the Three Gorges dam on the 6500 km long Yangtze river 20 CIVIL ENGINEERING THE THREE GORGES DAM, CHINA in the 1998 flood, the cost of providing emergency protection for the city of Wuhan, other downstream cities and areas of cultivated land together with the cost of clearing up flood damage was comparable with the capital cost of the ‘‘proposed dam ’’ Fig. 3. Artist’s impression of the completed dam showing the ship lift and ship lock on the righthand side of the picture funding is through loans and a tax on contracts for mechanical and electrical damage was comparable with the capital energy consumption throughout the coun- equipment were open to international cost of the proposed dam. Flooding also try. Another benefit of the project is competition and won by consortia from appears to have become more frequent in improved navigation on the river from North America and Europe. Construct- recent years as a result of cutting down Shanghai on the coast to the inland city of ion started in 1993 and impounding and trees in the upper catchment area to clear Chongqing, a distance of about 3500 km. first power generation is due to start in land for agriculture. The most expensive single part of the 2003. Completion is scheduled for 2009 The Yangtze river (known as Chang project is the programme to move more at a final cost approaching £15 billion. Jiang in Chinese) rises in the plateau area than one million people from the area to of southern Qinghai province in north- be flooded into new houses above the Flooding history of the Yangzte west China. This is part of the eastern proposed reservoir level. An environmen- The primary purpose of the Three Tibetan plateau at an elevation of about tal impact study identified both positive Gorges project is flood control. Major 4000 to 5000 m with adjacent mountains and negative consequences of the project floods causing damage and loss of life in rising to more than 6500 m. The river and the authorities say they have taken the industrial and agricultural areas then flows 6300 km through southern steps to solve the negative consequences. downstream of the dam site occurred in China to the sea at Shanghai. About two- The dam is a conventional gravity dam 1870, 1931, 1935, 1954, 1981,1991 and thirds along its length the river passes located on a foundation of sound and again in 1998. through a series of narrow limestone and apparently impermeable granite. It is the The scale of the problem can be appre- sandstone gorges which extend for nearly largest hydroelectric project under con- ciated by the fact that, in the 1998 flood, 200 km. Near the downstream end of struction at present and is setting new the cost of providing emergency protec- these gorges at the town of Sandouping, records for volumes and rates of con- tion for the city of Wuhan, other down- the bedrock is granite and it is this site struction. The civil engineering contracts stream cities and areas of cultivated land which first attracted attention as a suit- were awarded to Chinese contractors but together with the cost of clearing up flood able location for a dam. CIVIL ENGINEERING 21 FREER by the trade and domestic wastes from adjacent cities. The city of Chongqing Shiplock alone produces an estimated 1200 Mt of industrial wastewater and 300 Mt of sewage every year. At present only about a third of the industrial wastewater is treated and almost none of the sewage. Shiplift The World Bank has contributed £62 million for building new sewage works and a further £156 million for treating Power plant wastewater and solid wastes. Yangtse River Dam conventional in all but size The components of the dam are Spillway straightforward and conventional—it is the size of the project that is unusual. The main structure is a concrete gravity dam 2·3 km long founded on granite and with a maximum height of 183 m. The dam crest level will be at an eleva- 0km2tion of 185 m, the normal top water level will be 175 m and the downstream Fig. 4. Plan view of the Three Gorges dam site river level will be typically between 62 and 83 m. The new reservoir will cover an area of 1100 km2 (about twice the size of the Isle The first serious proposal to build a • a better supply of irrigation water to of Man) and will extend back to the city dam at the gorges was put forward in the farming areas downstream of Chongqing, 660 km upstream. The 1919 by Dr Sun Yat-sen, founder of • better control of the salinity of the spillway section will be in the centre of modern China, but the Japanese war, the water in the estuary region near the river channel with a power station on civil war and the communist revolution Shanghai. each side (Figs 3 and 4). delayed political approval until 1992. A ship lift and ship lock on the north Once impounding of the reservoir side of the dam will enable ships to pass Benefits of the project starts in 2003 it will be necessary to between the reservoir and the river As part of the preliminary studies for ensure that the reservoir is not polluted (Fig. 5). the project, a comprehensive environmen- tal impact study of the whole Yangtze basin was undertaken. This demonstrated that there were positive impacts in the middle and lower reaches of the river, and negative impacts in the reservoir area, but the negative impacts could be alleviated by suitable countermeasures. As well as mitigating the downstream flood levels, the other benefits of the pro- ject are • the capacity to transfer water from the Yangtze basin to Beijing and to other cities in northern China where there is a shortage of water • a large hydroelectric power station (at present the largest under construction) • improved navigation on the river • a new source of food by the introduc- tion of fish farming and aquaculture Fig. 5. Model of the completed project, looking west in the new reservoir 22 CIVIL ENGINEERING THE THREE GORGES DAM, CHINA The largest single undertaking in the Three Gorges project is the relocation of ‘‘people and industry from the area to be flooded by the new reservoir’’ Fig. 6. The Three Gorges layout is based on the Gezhouba dam, built 20 years ago, and 38 km downstream The layout is similar to that of the improved river regulation. Silt is dis- reservoir level are being built for 1·1 mil- smaller Gezhouba dam built across the charged through silt traps on the lion people (Fig. 8). One third of the peo- Yangtze around 20 years ago at Yi upstream side of each turbine and 27 ple to be moved from the area to be Chang, 38 km downstream of the Three sluices in the dam. There is no provision flooded are farmers and finding new land Gorges site (Fig. 6). This was the first for a fish pass in the Gezhouba dam and for them to farm is more difficult than dam built across the Yangtze river and it new spawning grounds for the Chinese allocating land for urban housing and was intended that the experience gained sturgeon, which used to pass upstream industry. from designing, building and operating it to spawn, have been developed down- The area of existing agricultural land would be incorporated in the design of stream of the dam.