Three Gorges Dam
Three Gorges Dam 三峡大å | |
The dam in September 2009 | |
Country | China |
---|---|
Location | Sandouping, Yiling District, Hubei |
Purpose | Flood control, power, navigation |
Status | Operational |
Construction began | December 14, 1994 |
Opening date | 2009[1] |
Construction cost | ¥203 billion (US$28.42 billion) estimate, ¥180 billion (US$25.20 billion)[2] |
Owner(s) | China Yangtze Power (subsidiary of China Three Gorges Corporation) |
Dam and spillways | |
Type of dam | Gravity dam |
Impounds | Yangtze River |
Height | 181Â meters (594Â ft) |
Length | 2,335Â meters (7,661Â ft) |
Width (crest) | 40 meters (131 ft) |
Width (base) | 115 meters (377 ft) |
Dam volume | 27.2 million cubic meters (35.6 million cu yd) |
Spillway capacity | 116,000 cubic meters per second (4,100,000 cu ft/s) |
Reservoir | |
Creates | Three Gorges Reservoir |
Total capacity | 39.3 cubic kilometers (31,900,000 acre⋅ft) |
Catchment area | 1,000,000 square kilometers (390,000 sq mi) |
Surface area | 1,084 square kilometers (419 sq mi)[3] |
Maximum length | 600 kilometers (370 mi)[4] |
Normal elevation | 175 meters (574 ft) |
The Three Gorges Dam (Chinese: 三峡大å, traditional Chinese: 三峽大壩; pinyin: SÄnxiá Dà bà ) 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. The world's largest power station in terms of installed capacity (22,500 MW), the Three Gorges Dam generates 95±20 TWh of electricity per year on average, depending on the amount of precipitation in the river basin. After the extensive monsoon rainfalls of 2020, the dam's annual production reached nearly 112 TWh, breaking the previous world record of ~103 TWh set by Itaipu Dam in 2016.
In addition to generating electricity, the dam was designed to increase the Yangtze River's shipping capacity. By providing flood storage space, the dam reduces the potential for flooding downstream, which historically plagued the Yangtze Plain. With the design of state-of-the-art large turbines, China regards the project as a monumental social and economic success. However, the dam has led to some ecological changes, including an increased risk of landslides, which have made it controversial both domestically and worldwide.
History
Sun Yat-sen envisioned a large dam across the Yangtze River in 1919.[6] 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".[7] 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.[8] No construction work was performed because of the Nationalists' worsening situation in the Chinese Civil War.[9]
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.
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. The need to develop hydroelectric power was emphasized.[9]
The National People's Congress approved the dam in 1992, and 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.[10] The last major component of the project, the ship lift, was completed in 2015 and began operation in 2016.[11]
Composition and dimensions
Made of concrete and steel, the dam is 2,335Â meters (2,554Â yd) long and 185Â meters (607Â ft) above sea level at its top. The project used 27.2 million cubic meters (35.6 million cu yd) 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 cubic meters (134.2 million cu yd) of earth.[12] The concrete dam wall is 181Â meters (594Â ft) high above the rock basis.
When the water level is at its maximum of 175 meters (574 ft) above sea level, 110 meters (361 ft) higher than the river level downstream, the dam reservoir is on average about 660 kilometers (410 mi) in length and 1.12 kilometers (3,675 ft) in width. It contains 39.3 cubic kilometers (31,900,000 acre⋅ft) of water and has a total surface area of 1,045 square kilometers (403 sq mi).[12]
Cost
The total cost of the Three Gorges Dam project was originally estimated at 203Â billion yuan (US$28.42 billion), but the cost fell to 180 billion yuan (US$25.20 billion) due to lower inflation rate during construction.[2] Total cost recovery was expected to be completed ten years after the dam became fully operational. The dam began to generate a profit in 2003 when the first batch of power generating units were put into production. The entire cost of the project has been recovered.[13]
Funding sources include the Three Gorges Dam Construction Fund, profits from the Gezhouba Dam, loans from the China Development Bank, loans from domestic and foreign commercial banks, corporate bonds, and revenue from both before and after the dam had become fully operational.[13]
Power generation and distribution
The world's largest power station in terms of installed capacity (22,500 MW),[14][15] the Three Gorges Dam generates 95±20 TWh of electricity per year on average, depending on the amount of precipitation in the river basin. After the extensive monsoon rainfalls of 2020, the dam's annual production reached nearly 112 TWh, breaking the previous world record of ~103 TWh set by Itaipu Dam in 2016.[16]
The dam's body was completed in 2006; the power plant was completed and fully operational by 2012, when the last of the main water turbines in the underground plant began production.
Generators
The dam is equipped with 34 turbo generators with a combined generating capacity of 22.5 million kilowatts. The main generators each weigh approximately 6,000Â tonnes and are designed to produce more than 700Â MW of power each.[17]
The designed hydraulic head of the generators is 80.6 meters (264 ft). The flow rate varies between 600–950 cubic meters per second (21,000–34,000 cu ft/s) depending on the head available; the greater the head, the less water needed to reach full power.
Three Gorges uses Francis turbines manufactured by two joint ventures: Alstom, ABB, Kvaerner, and the Chinese company Harbin Motor; and Voith, General Electric, Siemens (abbreviated as VGS), and the Chinese company Oriental Motor.[18]
Distribution
The power generated by the plant is transmitted through the Three Gorges Project (TGP) power transmission and transformation network to the Central China, Eastern China, Southern China, and Sichuan-Chongqing Power Grid. Power is converted from 20kV Alternating Current (AC) for distributed over multiple 500 kV transmission lines. Electricity to Central China Power Grid and Sichuan-Chongqing Power Grid is directly transmitted through 500kV AC transmission lines, whereas that for Eastern China Power Grid and Southern China Power Grid is first sent to a convertor station for conversion into 500kV direct current (DC) before being transmitted through long-distance DC transmission lines.[18]
In addition to generating electricity, the dam was designed to increase the Yangtze River's shipping capacity.
Locks
The installation of ship locks was intended to increase river shipping as well as making it safer, since the gorges are notoriously dangerous to navigate.
There are two series of ship locks installed near the dam. Each of them is made up of five stages, with transit time at around four hours. The freight capacity of the river has increased six times and the cost of shipping was reduced by 25 percent. In 2022, their cargo turnover reached 159.65 million tons, with an annual increase of 6 percent over the past few years.[19]
These locks are staircase locks, whereby inner lock gate pairs serve as both the upper gate and lower gate. The gates are the vulnerable hinged type, which, if damaged, could temporarily render the entire flight unusable. As there are separate sets of locks for upstream and downstream traffic, this system is more water efficient than bi-directional staircase locks.
Ship lift
In addition to the canal locks, there is a ship lift, a kind of elevator for vessels. The ship lift can lift ships of up to 3,000Â tons.[11] The ship lift's design uses a helical gear system, to climb or descend a toothed rack.
The elevator trials finished in July 2016, and the first cargo ship was lifted on July 15; the lift time comprised 8 minutes. Shanghai Daily reported that the first operational use of the lift was on September 18, 2016, when limited "operational testing" of the lift began.[20]
Portage railways
Construction of short portage railways bypassing the dam area altogether is planned. Two short rail lines, one on each side of the river, are to be constructed. The 88 kilometers (55 mi) northern portage railway (北岸翻åé“è·¯) will run from the Taipingxi port facility (太平溪港) on the northern side of the Yangtze, just upstream from the dam, via Yichang East Railway Station to the Baiyang Tianjiahe port facility in Baiyang Town (白洋镇), below Yichang. The 95 kilometers (59 mi) southern portage railway (å—岸翻åé“è·¯) will run from Maoping (upstream of the dam) via Yichang South Railway Station to Zhicheng (on the Jiaozuo–Liuzhou Railway).[21]
Flood control
An important function of the dam is to control flooding, which is a major problem for the seasonal river of the Yangtze. Millions of people live downstream of the dam, with many large, important cities like Wuhan, Nanjing, and Shanghai located adjacent to the river. Large areas of farmland and China's most important industrial area are situated beside the river.
The reservoir's flood storage capacity is 22 cubic kilometers (5.3 cu mi; 18 million acreâ‹…ft). This capacity will reduce the frequency of major downstream flooding from once every 10 years to once every 100Â years. The dam is expected to minimize the effect of even a "super" flood. However, the dam cannot protect against some of the large tributaries downstream, including the Xiang, Zishui, Yuanshui, Lishui, Hanshui, and Gan.
Environmental impact
The Three Gorges Dam impacts the environment in several ways, including disruption of the river flow which affects ecosystems downstream, sedimentation, erosion, and increased seismic activity. By providing flood storage space, the dam reduces the potential for flooding downstream, which historically plagued the Yangtze Plain. In 1931, floods on the river caused the deaths of up to 4Â million people. As a result, China regards the project as a monumental social and economic success. But the dam has led to ecological changes which have made it controversial domestically and abroad.[22][23]
Sedimentation
At current levels, 80 percent of the land in the area is eroding, depositing about 40Â million tons of sediment into the Yangtze annually.[24] Because the flow is slower above the dam, much of this sediment settles there instead of flowing downstream, and there is less sediment downstream.
The absence of silt downstream has three effects:
- Downstream riverbanks may become more vulnerable to flooding.
- Shanghai, more than 1,600 kilometers (990 mi) away, rests on a massive sedimentary plain. The "arriving silt – so long as it does arrive – strengthens the bed on which Shanghai is built ... the less the tonnage of arriving sediment the more vulnerable is this biggest of Chinese cities to inundation."[25]
- Benthic sediment buildup causes biological damage and reduces aquatic biodiversity.[26]
Landslides
The dam sits on a seismic fault. The Three Gorges Dam significantly increased seismic activity along the dam’s reservoir, triggering over 3,000 earthquakes from mid-2003 to the end of 2009, as well as numerous landslides.[27]
Erosion in the reservoir, induced by rising water, causes frequent major landslides that have led to noticeable disturbance in the reservoir surface as well as the evacuation of 300,000 people.[28]
Waste management
Over one billion tons of wastewater are released annually into the river,[24] which was more likely to be swept away before the reservoir was created. This has left the water stagnant, polluted and murky. As a result, improved upstream wastewater treatment around Chongqing and its suburban areas is required.[29]
Forest cover
In 1997, the Three Gorges area had only 10 percent forestation, down from 20% percent in the 1950s.[24]
Research by the United Nations Food and Agriculture Organization suggested that the Asia-Pacific region would gain about 6,000 square kilometers (2,300 sq mi) of forest by 2008. That is a significant change from the 13,000 square kilometers (5,000 sq mi) net loss of forest each year in the 1990s. This is largely due to China's large reforestation effort which accelerated after the 1998 Yangtze River floods convinced the government that it should restore tree cover, especially in the Yangtze's basin upstream of the Three Gorges Dam.[30]
Wildlife
This region has long been known for its rich biodiversity. It is home to 6,388 plant species, which belong to 238 families and 1,508 genera. Of these species, 57 are endangered.[31] These rare species are also used as ingredients in traditional Chinese medicines.[32] The proportion of forested area in the region surrounding the Three Gorges Dam dropped from 20 percent in 1950 to less than 10 percent in 2002, adversely affecting all plant species there.[32]
The region also provides habitats to hundreds of freshwater and terrestrial animal species.[31] Freshwater fish are especially affected by dams due to changes in the water temperature and flow regime. Many other fish are injured in the hydroelectric plants' turbine blades. This is particularly detrimental to the region's ecosystem because the Yangtze River basin is home to 361 different fish species and accounts for 27 percent of China's endangered freshwater fish species.[33] Other aquatic species have been endangered by the dam, particularly the baiji, or Chinese river dolphin,[24] now extinct.
Terrestrial impact
In 2005, NASA scientists calculated that the shift of water mass stored by the dams is affecting Earth's rotation. It will increase the total length of the Earth's day by 0.06 microseconds and make the Earth slightly more round in the middle and flat on the poles. The dam's ability to modify Earth's rotation was linked to the 2004 Indian Ocean earthquake and tsunami.[34] A study published in 2022 in the journal [Open Geosciences suggests that the change of reservoir water level affects the gravity field in western Sichuan, which in turn affects the seismicity in that area.[35]
Other impacts
Upstream dams
In order to maximize the utility of the Three Gorges Dam and cut down on sedimentation from the Jinsha River, a series of dams are being constructed on the Jinsha.[36]
These include the now completed Wudongde, Baihetan, Xiluodu,[37] and Xiangjiaba dams. Baihetan became fully operational in 2022.[38] Wudongde was opened in June 2021.
Displacement of residents
A controversial aspect of the dam project is the impact on people who lived on the banks of the river. Over one million people were displaced and their homes destroyed, as well as farmlands flooded in order to build the dam's reservoir. Two cities, 114 towns, and 1,680 villages were submerged during construction.[39] The people were moved to new homes by the Chinese government, which considered the displacement justified by the flood protection provided for the communities downstream of the dam.
Between 2002 and 2005, Canadian photographer Edward Burtynsky documented the impact of the project on the surrounding areas, including the town of Wanzhou.[40] Other photographers who recorded the change include Chengdu-based Muge,[41] Paris-based Zeng Nian (originally from Jiangsu),[42] and Israeli Nadav Kander.[43] Their work illustrates the importance of the Yangtze River to China, while also reminding us of the human and environmental cost of industrial development.
Culture and history
The area which filled with water in the reservoir behind the dam included locations with significant cultural history. The State Council authorized a ¥505 million archaeology salvage effort, and over the course of several years, archaeologists excavated 723 sites and conducted surface archaeology recovery missions at an additional 346 sites. Archaeologists recovered 200,000 artifacts of which 13,000 were considered as particularly historically or culturally notable. As part of this effort, the old Chongqing City Museum was replaced by the Chongqing China Sanxia Museum to house many of the recovered artifacts.[9]
Recovered structures that were too large for museums were moved upland to reconstruction districts (fu jian qu), which are outdoor museum parks. Recovered structures placed in such parks include temples, pavilions, houses, and bridges, among others.[9]
Some sites could not be moved because of their location, size, or design, such as the hanging coffins site high in the Shen Nong Gorge, part of the cliffs.[44]
Notes
- ↑ Three Gorges Dam Construction: Schedule from 1992 to 2009 Travel China Guide. Retrieved November 7, 2024.
- ↑ 2.0 2.1 Three Gorges Dam Hydro Electric Power Plant, China PowerTechnology. Retrieved November 7, 2024.
- ↑ Three Gorges Project Chinese National Committee on Large Dams. Retrieved November 7, 2024.
- ↑ Giorgio Lollino, Daniele Giordan, Giovanni B. Crosta, Jordi Corominas, Rafig Azzam, Janusz Wasowski, and Nicola Sciarra (eds.), Engineering Geology for Society and Territory - Volume 2: Landslide Processes (Springer, 2015, ISBN 978-3319090566).
- ↑ Mao Zedong, "Swimming" Marxists.org. Retrieved November 8, 2024.
- ↑ Lin Yang, China’s Three Gorges Dam Under Fire TIME (October 12, 2007). Retrieved November 8, 2024.
- ↑ Abel Wolman and W.H. Lyles, John Lucian Savage: 1879—1967 National Academy of Sciences, 1978. Retrieved November 8, 2024.
- ↑ China's Dream Dam Popular Science 148(6): 98. Retrieved November 8, 2024.
- ↑ 9.0 9.1 9.2 9.3 Stevan Harrell, An Ecological History of Modern China (University of Washington Press, 2023, ISBN 978-0295751719).
- ↑ Three Gorges Dam now at full capacity China Daily (July 5, 2012). Retrieved November 8, 2024.
- ↑ 11.0 11.1 World's largest shiplift starts operation at China's Three Gorges Dam Shanghai Daily (September 18, 2016). Retrieved November 8, 2024.
- ↑ 12.0 12.1 Richard W. Wertz, Three Gorges Dam Project – Quick Facts Exploring Chinese History. Retrieved November 19, 2024.
- ↑ 13.0 13.1 Three Gorges Dam Cost: How much did it cost to build such a huge project? Travel China Guide. Retrieved November 19, 2024.
- ↑ Cutler J. Cleveland and Christopher G. Morris, Handbook of Energy Volume II: Chronologies, Top Ten Lists, and Word Clouds (Elsevier Science, 2013, ISBN 978-0124170131).
- ↑ Robert Ehrlich, Harold A. Geller, and John R. Cressman, Renewable Energy: A First Course (CRC Press, 2022, ISBN 978-0367768379).
- ↑ Three Gorges Dam sets power generation record in 2020 China Daily (January 1, 2021). Retrieved November 19, 2024.
- ↑ Fabian Acker, Taming the Yangtze The Institution of Engineering and Technology E-News (March 2, 2009). Retrieved November 19, 2024.
- ↑ 18.0 18.1 Three Gorges Dam Hydropower Station NS Energy (October 5 2018). Retrieved November 19, 2024.
- ↑ Shipping throughput of Three Gorges Dam hits new record Xinhua (February 22, 2023). Retrieved November 20, 2024.
- ↑ World's largest shiplift starts operation at China's Three Gorges Dam Shanghai Daily (September 18, 2016). November 20, 2024.
- ↑ Railroad construction accelerates for Three Gorges’ port The State Council: People's Republic of China (February 22, 2023). Retrieved November 20, 2024.
- ↑ Michael Laris, Untamed Waterways Kill Thousands Yearly The Washington Post (August 17, 1998). Retrieved November 20, 2024.
- ↑ Roseanne Gerin, Rolling on A River Beijing Review (December 11, 2008). Retrieved November 20, 2024.
- ↑ 24.0 24.1 24.2 24.3 Dai Qing (ed.), The River Dragon Has Come!: Three Gorges Dam and the Fate of China's Yangtze River and Its People (Routledge, 1998, ISBN 978-0765602060).
- ↑ Simon Winchester, The River at the Center of the World: A Journey Up the Yangtze, and Back in Chinese Time (Picador, 2004, ISBN 978-0312423377).
- ↑ Hendrik Segers and Koen Martens, Aquatic Biodiversity II: The Diversity of Aquatic Ecosystems (Springer, 2020, ISBN 978-9402417838).
- ↑ Before and after the Three Gorges Dam for the Yangtze River USGS, November 17, 2016. Retrieved November 20, 2024.
- ↑ Patricia Adams, Chinese study reveals Three Gorges Dam triggered 3,000 earthquakes, numerous landslides Probe International (June 1, 2011). Retrieved November 20, 2024.
- ↑ Lisa Peryman, Three Gorges Dam tipped scales on river waste dump problem Probe International (March 1, 2013). Retrieved November 20, 2024.
- ↑ Peter Collins, Falling here, rising there The Economist (November 15, 2007). Retrieved November 20, 2024.
- ↑ 31.0 31.1 J. Wu, J. Huang, X. Han, Z. Xie, and X. Gao, Three-Gorges Dam – Experiment in Habitat Fragmentation? Science 300(5623) (2003): 1239–1240. Retrieved November 20, 2024.
- ↑ 32.0 32.1 Deirdre Chetham, Before the Deluge: The Vanishing World of the Yangtze's Three Gorges (Palgrave Macmillan, 2002, ISBN 0312214170).
- ↑ P. Xie, Three-Gorges Dam: Risk to Ancient Fish Science 302(5648) (2003): 1149b–1151. Retrieved November 20, 2024.
- ↑ NASA reveals impact of China's Three Gorges Dam on Earth's rotation Education Post (September 25, 2024). Retrieved November 20, 2024.
- ↑ X. Wang et al., Influence of Three Gorges Dam on earthquakes based on GRACE gravity field Open Geosciences 14(1) (January 2022): 453–461. Retrieved November 20, 2024.
- ↑ Richard High, Jinsha River Dams KHL Group (June 17, 2009). Retrieved November 21, 2024.
- ↑ Xiluodu Dam, Jinsha River, China Power Technology (October 6 2016). Retrieved November 21, 2024).
- ↑ New mega hydropower station to begin operations Xinhua (April 8, 2021). Retrieved November 21, 2024.
- ↑ Nectar Gan, China’s Three Gorges Dam is one of the largest ever created. Was it worth it? CNN (July 31, 2020). Retrieved November 21, 2024.
- ↑ Edward Burtynsky, Edward Burtynsky: Three Gorges Dam Project MacKenzie Art Gallery. Retrieved November 21, 2024.
- ↑ Gem Fletcher, Muge travels the Yangtze River, tenderly photographing communities displaced by flooding British Journal of Photography (December 14, 2020). Retrieved November 21, 2024.
- ↑ Zeng Nian, Remembering the Three Gorges Dam Angkor Photo Festival & Workshops (December 5, 2014). Retrieved November 21, 2024.
- ↑ Jean Dykstra, Nadav Kander: Yangtze: The Long River Photograph (December 27, 2012). Retrieved November 21, 2024.
- ↑ Shen Nong Gorge Hanging Coffins The Megalithic Portal. Retrieved November 21, 2024.
ReferencesISBN links support NWE through referral fees
- Chetham, Deirdre. Before the Deluge: The Vanishing World of the Yangtze's Three Gorges. Palgrave Macmillan, 2002. ISBN 0312214170
- Cleveland, Cutler J., and Christopher G. Morris. Handbook of Energy Volume II: Chronologies, Top Ten Lists, and Word Clouds. Elsevier Science, 2013. ISBN 978-0124170131
- Ehrlich, Robert, Harold A. Geller, and John R. Cressman. Renewable Energy: A First Course. CRC Press, 2022. ISBN 978-0367768379
- Harrell, Stevan. An Ecological History of Modern China. University of Washington Press, 2023. ISBN 978-0295751719
- Lollino, Giorgio, Daniele Giordan, Giovanni B. Crosta, Jordi Corominas, Rafig Azzam, Janusz Wasowski, and Nicola Sciarra (eds.) Engineering Geology for Society and Territory - Volume 2: Landslide Processes. Springer, 2015. ISBN 978-3319090566
- Qing, Dai (ed.). The River Dragon Has Come!: Three Gorges Dam and the Fate of China's Yangtze River and Its People. Routledge, 1998. ISBN 978-0765602060
- Segers, Hendrik, and Koen Martens. Aquatic Biodiversity II: The Diversity of Aquatic Ecosystems. Springer, 2020. ISBN 978-9402417838
- Winchester, Simon. The River at the Center of the World: A Journey Up the Yangtze, and Back in Chinese Time. Picador, 2004. ISBN 978-0312423377
External links
All links retrieved November 21, 2024.
- Three Gorges Dam, China U.S. Department of the Interior
- It's True: China’s Three Gorges Dam Is So Big It Changes Earth's Spin IFLScience
- Three Gorges: A “Mega-Dam†and Its Impacts College of Earth and Mineral Sciences, Penn State
- The Three Gorges Dam in China: Forced Resettlement, Suppression of Dissent and Labor Rights Concerns Human Rights Watch
- Problems with the Three Gorges Dam Facts and Details
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