The Three Gorges Dam (), officially known as Yangtze River Three Gorges Water Conservancy Project () is a

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

gravity dam A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation. Gravity dams are designed so that each section of the dam is ...

that spans the

Yangtze River The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the third-longest in the world. It rises at Jari Hill in the Tanggula Mountains of the Tibetan Plateau and flows including Dam Qu River the longest source of the Yangtze, i ...

near

Sandouping Sandouping (}) is a town in Yiling District of Yichang prefecture-level city in the Chinese province of Hubei. It is located on the right (southern) bank of the Yangtze River, next to Yiling District's border with Zigui County to the west. Sa ...

Yiling District Yiling District () is a district of the prefecture-level city of Yichang, Hubei province, People's Republic of China. Created on July 30, 2001, the district includes most of the former Yichang County, with the exception of Yichang center city (whi ...

, Yichang, Hubei province, central China, downstream of the

Three Gorges The Three Gorges () are three adjacent and sequential gorges along the middle reaches of the Yangtze River path, in the hinterland of the People's Republic of China. With a subtropical monsoon climate, they are known for their scenery. The T ...

. The world's 27th largest dam by reservoir volume, and the world's largest power station by

installed capacity Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, maximum effect or gross capacity,MW), the Three Gorges Dam generates 95±20

TWh TWH or twh could refer to: * Tai Dón language, a language of Vietnam, Laos, and China * Tai Wo Hau station, Hong Kong; MTR station code * Tennessee Walking Horse, a breed of horse * Toronto Western Hospital, a hospital in Toronto, Canada * Tun ...

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

per year on average, depending on the amount of precipitation in the river basin. After the extensive monsoon rainfalls of 2020, the dam produced nearly 112 TWh in a year, breaking the previous world record of ~103 TWh set by the

Itaipu Dam The Itaipu Dam ( ; ; ) is a hydroelectric dam on the Paraná River located on the border between Brazil and Paraguay. It is the third largest hydroelectric dam in the world, and holds the 45th largest reservoir in the world. The name "Itai ...

in 2016. The dam's body was completed in 2006; the power plant became fully operational in 2012, when the last of the main

water turbine A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now, t ...

s in the underground plant began production. The last major component of the project, the ship lift, was completed in 2015. The dam, measuring 185 meters in height and 2,309 meters in width, significantly surpasses Brazil’s 12,600 MW Itaipu facility and is one of the world's largest hydroelectric plants. Each of the main water turbines,

state-of-the-art The state of the art (SOTA or SotA, sometimes cutting edge, leading edge, or bleeding edge) refers to the highest level of general development, as of a device, technique, or scientific field achieved at a particular time. However, in some contex ...

at their installation, has a capacity of 700 MW. Combining the capacity of the dam's 32 main turbines with the two smaller generators (50 MW each) that provide power to the plant itself, the total electric generating capacity of the Three Gorges Dam is 22,500 MW with minimal

greenhouse gas emissions Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (), from burning fossil fuels such as coal, petroleum, oil, and natural gas, is the main cause of climate chan ...

. The dam enhances the Yangtze River's shipping capacity and provides

flood control Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...

, helping to protect millions of people from severe flooding on the

Yangtze Plain The Yangtze Plain ( Chinese: 長江中下游平原/长江中下游平原; Wade-Giles: Ch'ang Chiang P'ing-yüan; Pinyin: Chang Jiang Pingyuan) is made up of a series of alluvial plains along the Yangtze River and its major tributaries. The Yangt ...

. 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, and 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 Sun Yat-senUsually known as Sun Zhongshan () in Chinese; also known by Names of Sun Yat-sen, several other names. (; 12 November 186612 March 1925) was a Chinese physician, revolutionary, statesman, and political philosopher who founded the Republ ...

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

. In 1932, the

Nationalist government The Nationalist government, officially the National Government of the Republic of China, refers to the government of the Republic of China (1912–1949), Republic of China from 1 July 1925 to 20 May 1948, led by the nationalist Kuomintang (KMT ...

, led by Chiang Kai-shek, began preliminary work on plans in the Three Gorges. In 1939, during the

Second Sino-Japanese War The Second Sino-Japanese War was fought between the Republic of China (1912–1949), Republic of China and the Empire of Japan between 1937 and 1945, following a period of war localized to Manchuria that started in 1931. It is considered part ...

, Japanese military forces occupied

Yichang Yichang ( zh, s= ), Postal Map Romanization, alternatively romanized as Ichang, is a prefecture-level city located in western Hubei province, China. Yichang had a population of 3.92 million people at the 2022 census, making it the third most pop ...

and surveyed the area. In 1944, the

United States Bureau of Reclamation The Bureau of Reclamation, formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and operatio ...

's head design engineer,

John L. Savage John Lucian Savage (December 25, 1879 – December 28, 1967) was an American civil engineer. Among the 60 major dams he supervised the designs for, he is best known for Hoover Dam, Shasta Dam, Parker Dam and Grand Coulee Dam in the United State ...

, 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 Mao Zedong pronounced ; traditionally Romanization of Chinese, romanised as Mao Tse-tung. (26December 18939September 1976) was a Chinese politician, revolutionary, and political theorist who founded the People's Republic of China (PRC) in ...

supported the project, but began the

Gezhouba Dam The Gezhouba Dam or Gezhouba Water Control Project () on the Yangtze River is located in the western suburbs of Yichang, in central China's Hubei province. One of the largest run-of-the-river dams, it sits several kilometers upstream from downto ...

project nearby first, and economic problems including the

Great Leap Forward The Great Leap Forward was an industrialization campaign within China from 1958 to 1962, led by the Chinese Communist Party (CCP). Party Chairman Mao Zedong launched the campaign to transform the country from an agrarian society into an indu ...

and the

Cultural Revolution The Cultural Revolution, formally known as the Great Proletarian Cultural Revolution, was a Social movement, sociopolitical movement in the China, People's Republic of China (PRC). It was launched by Mao Zedong in 1966 and lasted until his de ...

slowed progress. After the

1954 Yangtze River Floods From June to September 1954, the Yangtze River Floods were a series of catastrophic floodings that occurred mostly in Hubei Province. Due to unusually high volume of precipitation as well as an extraordinarily long rainy season in the middle stre ...

, in 1956, Mao wrote "

Swimming Swimming is the self-propulsion of a person through water, such as saltwater or freshwater environments, usually for recreation, sport, exercise, or survival. Swimmers achieve locomotion by coordinating limb and body movements to achieve hydrody ...

", a poem about his fascination with a dam on the Yangtze River. In 1958, after the

Hundred Flowers Campaign The Hundred Flowers Campaign, also termed the Hundred Flowers Movement ( zh, s=百花齐放, p=Bǎihuā Qífàng) and the Double Hundred Movement ( zh, labels=no, s=双百方针, p=Shuāngbǎi Fāngzhēn), was a period from 1956 to 1957 in the ...

, some engineers who spoke out against the project were imprisoned. During China's emphasis on the

Four Modernizations The Four Modernizations (simplified Chinese: 四个现代化; traditional Chinese: 四個現代化) were goals formally announced by China's first Premier Zhou Enlai to strengthen the fields of agriculture, industry, defense, and science and ...

during its early period of

Reform and Opening Up Reform and opening-up ( zh, s=改革开放, p=Gǎigé kāifàng), also known as the Chinese economic reform or Chinese economic miracle, refers to a variety of economic reforms termed socialism with Chinese characteristics and socialist market ...

, 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 The Chinese People's Political Consultative Conference (CPPCC) is a political advisory body in the People's Republic of China and a central part of the Chinese Communist Party (CCP)'s United front (China), united front system. Its members adv ...

became a center of opposition to the proposed dam. It convened panels of experts who recommended delaying the project. The

National People's Congress The National People's Congress (NPC) is the highest organ of state power of the People's Republic of China (PRC). The NPC is the only branch of government in China, and per the principle of unified power, all state organs from the Sta ...

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 A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the electricity generation, generation of electric power. Power stations are generally connected to an electr ...

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 above sea level by 2008 and to the designed maximum level of by 2010.

Composition and dimensions

Made of concrete and steel, the dam is long and above sea level at its top. The project used of concrete (mainly for the dam wall), used 463,000

tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...

s of steel (enough to build 63

Eiffel Tower The Eiffel Tower ( ; ) is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower from 1887 to 1889. Locally nicknamed "''La dame de fe ...

s), and moved about of earth. The concrete dam wall is high above the rock basis. When the water level is at its maximum of above sea level, higher than the river level downstream, the dam reservoir is on average about in length and in width. It contains of water and has a total surface area of . On completion, the reservoir flooded a total area of of land, compared to the of reservoir created by the

Economics

The Chinese government estimated that the Three Gorges Dam project would cost 180 billion yuan (US$22.5 billion). By the end of 2008, spending had reached 148.365 billion yuan, of which 64.613 billion yuan was spent on construction, 68.557 billion yuan on relocating affected residents, and 15.195 billion yuan on financing. It was estimated in 2009 that the cost of construction would be fully recouped when the dam had generated of electricity, yielding 250 billion yuan; total cost recovery was thus expected to be completed ten years after the dam became fully operational. In fact, the entire cost of the Three Gorges Dam was recovered by December 20, 2013. Funding sources include the Three Gorges Dam Construction Fund, profits from the

, loans from the

China Development Bank China Development Bank (CDB) is a policy bank of China under the State Council. Established in 1994, it has been described as the engine that powers the national government's economic development policies.

, loans from domestic and foreign commercial banks,

corporate bond A corporate bond is a bond issued by a corporation in order to raise financing for a variety of reasons such as to ongoing operations, mergers & acquisitions, or to expand business. It is a longer-term debt instrument indicating that a corpo ...

s, and revenue from both before and after the dam had become fully operational. Additional charges were assessed as follows: every province receiving power from the Three Gorges Dam had to pay an extra ¥7.00 per MWh, and the other provinces had to pay an additional charge of ¥4.00 per MWh. No surcharge was imposed on the

Tibet Autonomous Region The Tibet Autonomous Region (TAR), often shortened to Tibet in English or Xizang in Pinyin, Hanyu Pinyin, is an Autonomous regions of China, autonomous region of the China, People's Republic of China. It was established in 1965 to replace the ...

Power generation and distribution

Generating capacity

Power generation is managed by

China Yangtze Power China Yangtze Power Co., Ltd. (CYPC), known as Yangtze Power is a Chinese utilities company, headquartered in Beijing. The company is a component of SSE 180 Index. A controlling share is held by the parent company China Three Gorges Corporati ...

, a listed subsidiary of

China Three Gorges Corporation The China Three Gorges Corporation (CTG; ) is a Chinese state-owned power company, established on 27 September 1993. The company was responsible for the construction of the Three Gorges Dam-project, the world's largest hydroelectric power plant, t ...

(CTGC), a Central Enterprise administered by

SASAC The State-owned Assets Supervision and Administration Commission of the State Council (SASAC) is a special commission of the State Council of the People's Republic of China. It was founded in 2003 through the consolidation of various other indus ...

. The Three Gorges Dam is the world's largest capacity hydroelectric power station, with 34 generators: 32 main generators, each with a capacity of 700 MW, and two plant power generators, each with capacity of 50 MW, for a total of 22,500 MW. Among the 32 main generators, 14 are installed on the dam's north side, 12 on the south side, and the remaining six in the underground power plant in the mountain south of the dam. Annual electricity generation in 2018 was 101.6 TWh, which is 20 times more than the

Hoover Dam The Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado, Black Canyon of the Colorado River (U.S.), Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, d ...

Generators

The main generators each weigh about 6,000 tonnes and are designed to produce more than 700 MW of power each. The designed

hydraulic head Hydraulic head or piezometric head is a measurement related to liquid pressure (normalized by specific weight) and the liquid elevation above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22, eq.3.2a. It is usually meas ...

of the generators is . The flow rate varies between depending on the head available; the greater the head, the less water needed to reach full power. Three Gorges uses

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The pro ...

s with a diameter of 9.7/10.4 m (VGS design/Alstom's design) and a rotation speed of 75 revolutions per minute. This means that in order to generate power at 50 Hz, the generator rotors have 80 poles. Rated power is 778 MVA, with a maximum of 840 MVA and a

power factor In electrical engineering, the power factor of an AC power system is defined as the ratio of the ''real power'' absorbed by the electrical load, load to the ''apparent power'' flowing in the circuit. Real power is the average of the instantaneou ...

of 0.9. The generator produces electrical power at 20 kV. The electricity generated is then stepped up to 500 kV for transmission at 50 Hz. The generator's

stator The stator is the stationary part of a rotary system, found in electric generators, electric motors, sirens, mud motors, or biological rotors (such as bacterial flagella or ATP synthase). Energy flows through a stator to or from the rotat ...

, the biggest of its kind, is 3.1/3 m in height; the outer diameter of the stator is 21.4/20.9 m, the inner diameter is 18.5/18.8 m, and the bearing load is 5,050/5,500 tonnes. Average efficiency is over 94%, with a maximum efficiency of 96.5% reached. Sanxia Runner04 300

The generators were manufactured by two joint ventures:

Alstom Alstom SA () is a French multinational rolling stock manufacturer which operates worldwide in rail transport markets. It is active in the fields of passenger transportation, signaling, and locomotives, producing high-speed, suburban, regional ...

ABB ABB Group is a Swedish-Swiss multinational electrical engineering corporation. Incorporated in Switzerland as ABB Ltd., and headquartered in Zurich, it is dual-listed on the Nasdaq Nordic exchange in Stockholm, Sweden, and the SIX Swiss Excha ...

, Kvaerner, and the Chinese company Harbin Motor; and

Voith The Voith Group is a global technology company. With its broad portfolio of systems, products, services and digital applications, Voith trades in the markets of energy, paper, raw materials and transport. Founded in 1867, Voith today has aroun ...

General Electric General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the year ...

Siemens Siemens AG ( ) is a German multinational technology conglomerate. It is focused on industrial automation, building automation, rail transport and health technology. Siemens is the largest engineering company in Europe, and holds the positi ...

(abbreviated as VGS), and the Chinese company Oriental Motor. The technology transfer agreement was signed together with the contract. Most of the generators are water-cooled. Some of the newer ones are air-cooled, making them simpler in design and easier to manufacture and maintain.

Generator installation progress

The first north-side main generator (No. 2) started up on July 10, 2003. The north side became completely operational on September 7, 2005, with the implementation of generator No. 9. Full power (9,800 MW) was eventually achieved on October 18, 2006, after the water level reached 156 meters. On the south side, main generator No. 22 started up on June 11, 2007, and No. 15 became operational on October 30, 2008. The sixth (No. 17) began operation on December 18, 2007, raising capacity to 14.1 GW, exceeding that of Itaipu dam (14.0 GW) to become the world's largest hydro power plant by capacity. When the last main generator (No. 27) finished its final test on May 23, 2012, the six underground main generators were all operational, raising the capacity to 22.5 GW. After nine years of construction, installation and testing, the power plant was fully operational by July 2012.

Output milestones

Three gorges dam annual power output SVG

Three Gorges Dam Installed Units and TWh Over Years

By August 16, 2011, the plant had generated 500 TWh of electricity. In July 2008 it generated 10.3 TWh of electricity, its first month over 10 TWh. On June 30, 2009, after the river flow rate increased to over 24,000 m³/s, all 28 generators were switched on, producing only 16,100 MW because the head available during flood season is insufficient. During an August 2009 flood, the plant first reached its maximum output for a short period. During the November to May dry season, power output is limited by the river's flow rate, as seen in the diagrams on the right. When there is enough flow, power output is limited by plant generating capacity. The maximum power-output curves were calculated based on the average flow rate at the dam site, assuming the water level is 175 m and the plant gross efficiency is 90.15%. The actual power output in 2008 was obtained based on the monthly electricity sent to the grid. The Three Gorges Dam reached its design-maximum reservoir water level of for the first time on October 26, 2010, in which the intended annual power-generation capacity of 84.7 TWh was realized. It has a combined generating capacity of 22.5 gigawatts and a designed annual generation capacity of 88.2 TWh. In 2012, the dam's 32 generating units generated a record 98.1 TWh of electricity, which accounts for 14% of China's total hydro generation. Between 2012 (first year with all 32 generating units operating) and 2021, the dam generated an average of 97.22 TWh of electricity per year, higher than Itaipu dam's average of 89.22 TWh of electricity per year during the same period. Due to the extensive 2020 monsoon season rainfall, the annual production reached ~112 TWh that year, which broke the previous world record of annual production by Itaipu Dam equal to ~103 TWh.

Distribution

The State Grid Corporation and

China Southern Power Grid China Southern Power Grid Company Limited (CSG; ) is one of the two Chinese state-owned enterprises established in 2002 in a power system reform promulgated by the State Council of the People's Republic of China, State Council, the other being ...

paid a flat rate of ¥250 per MWh (US$35.7) until July 2, 2008. Since then, the price has varied by province, from ¥228.7 to ¥401.8 per MWh. Higher-paying customers, such as

Shanghai Shanghai, Shanghainese: , Standard Chinese pronunciation: is a direct-administered municipality and the most populous urban area in China. The city is located on the Chinese shoreline on the southern estuary of the Yangtze River, with the ...

, receive priority. Nine provinces and two cities consume power from the dam. Power distribution and transmission infrastructure cost about 34.387 billion yuan. Construction was completed in December 2007, one year ahead of schedule. Power is distributed over multiple 500 kV transmission lines. Three

direct current Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow throug ...

(DC) lines to the East China Grid carry 7,200 MW: Three Gorges – Shanghai (3,000 MW),

HVDC Three Gorges – Changzhou The HVDC Three Gorges – Changzhou is an long bipolar HVDC transmission line in China for the transmission of electric power from the Three Gorges power plant to the area of Changzhou. The transmission line went into service in 2004. It runs fr ...

(3,000 MW), and

HVDC Gezhouba – Shanghai A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages betwe ...

(1,200 MW). The

alternating current Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...

(AC) lines to the Central China Grid have a total capacity of 12,000 MW. The DC transmission line

HVDC Three Gorges – Guangdong The HVDC Three Gorges – Guangdong is a 940 kilometre-long bipolar HVDC transmission line in China for the transmission of electric power from the Three Gorges power plant to the area of Guangdong. The powerline went into service in 2004. I ...

to the South China Grid has a capacity of 3,000 MW. The dam was expected to provide 10% of China's power. However, electricity demand has increased more quickly than previously projected. Even fully operational and despite its size, on average, it supported only about 1.7% of electricity demand in China in the year of 2011, when the Chinese electricity demand reached 4,692.8 TWh.

Environmental impact

Emissions

According to the

National Development and Reform Commission The National Development and Reform Commission (NDRC) is the third-ranked executive department of the State Council of the People's Republic of China, which functions as a macroeconomic management agency. Established as the State Planning C ...

, 366 grams of coal would produce 1 kWh of electricity during 2006. From 2003 to 2007, power production equaled that of 84 million tonnes of standard coal.

Erosion and sedimentation

Two hazards are uniquely identified with the dam: that sedimentation projections are not agreed upon, and that the dam sits on a seismic fault. At current levels, 80% of the land in the area is eroding, depositing about 40 million tons of

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

into the

Yangtze The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the third-longest in the world. It rises at Jari Hill in the Tanggula Mountains of the Tibetan Plateau and flows including Dam Qu River the longest source of the Yangtze, i ...

annually. 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 Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

downstream has three effects: * Some hydrologists expect downstream riverbanks to become more vulnerable to flooding. * Shanghai, more than away, rests on a massive sedimentary plain. The "arriving siltso long as it does arrivestrengthens 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". *

Benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

sediment buildup causes biological damage and reduces aquatic

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

Landslides

Erosion in the reservoir, induced by rising water, causes frequent major landslides that have led to noticeable disturbance in the reservoir surface, including two incidents in May 2009 when somewhere between of material plunged into the flooded Wuxia Gorge of the Wu River. In the first four months of 2010, there were 97 significant landslides.

Waste management

Maoping-Drinking-water-source-protection-area-4937

The dam catalyzed improved upstream

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

treatment around

Chongqing ChongqingPostal Romanization, Previously romanized as Chungking ();. is a direct-administered municipality in Southwestern China. Chongqing is one of the four direct-administered municipalities under the State Council of the People's Republi ...

and its suburban areas. According to the Ministry of Environmental Protection, as of April 2007, more than 50 new plants could treat 1.84 million tonnes per day, 65% of the total need. About 32 landfills were added, which could handle 7,664.5 tonnes of solid waste every day. Over one billion tons of wastewater are released annually into the river, which was more likely to be swept away before the reservoir was created. This has left the water stagnant, polluted and murky.

Forest cover

In 1997, the Three Gorges area had 10% forestation, down from 20% in the 1950s. Research by the

United Nations The United Nations (UN) is the Earth, global intergovernmental organization established by the signing of the Charter of the United Nations, UN Charter on 26 June 1945 with the stated purpose of maintaining international peace and internationa ...

Food and Agriculture Organization The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...

suggested that the Asia-Pacific region would gain about of forest by 2008. That is a significant change from the net loss of forest each year in the 1990s. This is largely due to China's large reforestation effort. This accelerated after the

1998 Yangtze River floods The 1998 China floods (1998年中国洪水) lasted from middle of June to the beginning of September 1998 in China at the Yangtze RiverChinanews.com.cn.Chinanews.com.cn" ''98年特大洪水.'' Retrieved on 2009-08-01. as well as the Nen River, ...

convinced the government that it should restore tree cover, especially in the Yangtze's basin upstream of the Three Gorges Dam.

Wildlife

Concerns about the dam's impact on wildlife predate the National People's Congress's approval in 1992. 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. These rare species are also used as ingredients in traditional Chinese medicines. The proportion of forested area in the region surrounding the Three Gorges Dam dropped from 20% in 1950 to less than 10% as of 2002, adversely affecting all plant species there. The region also provides habitats to hundreds of freshwater and terrestrial animal species. 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% of China's endangered freshwater fish species. Other aquatic species have been endangered by the dam, particularly the baiji, or

Chinese river dolphin The baiji (''Lipotes vexillifer'') is a probably extinct species of freshwater dolphin native to the Yangtze river system in China. It is thought to be the first dolphin species driven to extinction due to the impact of humans. This dolphin is ...

, now extinct. In fact, Chinese Government scholars even claim that the Three Gorges Dam directly caused the extinction of the baiji. Of the 3,000 to 4,000 remaining

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

Siberian crane The Siberian crane (''Leucogeranus leucogeranus''), also known as the Siberian white crane or the snow crane, is a bird of the family Gruidae, the crane (bird), cranes. They are distinctive among the cranes: adults are nearly all White, snowy whi ...

, many spend the winter in wetlands that the Three Gorges Dam will destroy. Populations of the

Yangtze sturgeon Dabry's sturgeon (''Sinosturio dabryanus''), also known as the Yangtze sturgeon, Changjiang sturgeon and river sturgeon, is a species of fish in the sturgeon family, Acipenseridae.Zhuang, P., et al. (1997)Biology and life history of Dabry's s ...

are guaranteed to be "negatively affected" by the dam. In 2022 the

Chinese paddlefish The Chinese paddlefish (''Psephurus gladius''; : literal translation: "white sturgeon"), also known as the Chinese swordfish, is an Extinction, extinct species of fish that was formerly native to the Yangtze and Yellow River basins in China. Wit ...

was declared extinct, with the last confirmed sighting in 2003.

Terrestrial impact

In 2005, NASA scientists calculated that the shift of water mass stored by the dams would increase the total length of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

's day by 0.06

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is to one second, ...

s and make the Earth slightly more round in the middle and flat on the

poles Pole or poles may refer to: People *Poles (people), another term for Polish people, from the country of Poland * Pole (surname), including a list of people with the name * Pole (musician) (Stefan Betke, born 1967), German electronic music artist ...

. A study published in 2022 in the journal

Open Geosciences ''Open Geosciences'' is a peer-reviewed open-access scientific journal covering all aspects of the Earth sciences. It is published by De Gruyter and the editor-in-chief is Piotr Jankowski (San Diego State University). The journal was established i ...

suggests that the change of reservoir water level affects the gravity field in western Sichuan, which in turn affects the seismicity in that area.

Floods, agriculture, industry

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 Wuhan; is the capital of Hubei, China. With a population of over eleven million, it is the most populous city in Hubei and the List of cities in China by population, eighth-most-populous city in China. It is also one of the nine National cent ...

Nanjing Nanjing or Nanking is the capital of Jiangsu, a province in East China. The city, which is located in the southwestern corner of the province, has 11 districts, an administrative area of , and a population of 9,423,400. Situated in the Yang ...

, and

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 . This capacity will reduce the frequency of major downstream flooding from once every 10 years to once every 100 years. The dam is expected to minimize the effect of even a "super" flood. The river flooded in 1954 over an area of , killing 33,169 people and forcing almost 18.9 million people to move. The flood waters covered Wuhan, a city of eight million people, for over three months, and the Jingguang Railway was out of service for more than 100 days. The 1954 flood carried of water. The dam could only divert the water above

Chenglingji Chenglingji ( zh, s=城陵矶, t=城陵磯, p=Chénglíng jī) is a large rock located at the confluence of Dongting Lake and the Yangtze, within Yueyanglou District, Yueyang, Hunan. It is one of the three most famous rocks in the Yangtze, togeth ...

, leaving to be diverted. The dam cannot protect against some of the large tributaries downstream, including the Xiang, Zishui, Yuanshui,

Lishui Lishui (; Lishuinese: ''li⁶ syu³'' ) is a prefecture-level city in the southwest of Zhejiang province, People's Republic of China. It borders Quzhou, Jinhua and Taizhou to the north, Wenzhou to the southeast, and the province of Fujian to ...

Hanshui The Han River, also known by its Chinese names Hanshui and Hanjiang, is a major river in Central China. A left tributary of the Yangtze, the longest river in Asia, it has a length of and is the longest tributary of the Yangtze system. The ...

, and

Gan The word Gan or the initials GAN may refer to: Places * Gan, a component of Hebrew placenames literally meaning "garden" China * Gan River (Jiangxi) * Gan River (Inner Mongolia), * Gan County, in Jiangxi province * Gansu, abbreviated '' ...

. In 1998, a flood in the same area caused billions of dollars worth of damage, when of farmland were flooded. The flood affected more than 2.3 million people, killing 1,526. In early August 2009, the largest flood in five years passed through the dam site. During this flood, the dam limited the water flow to less than per second, raising the upstream water level from on August 1, to on August 8. A full of flood water was captured and the river flow was cut by as much as per second. The dam discharges its reservoir during the dry season every year, between December and March. This increases the flow rate of the river downstream, providing fresh water for agricultural and industrial usage, and improving shipping conditions. The water level upstream drops from , in preparation for the rainy season. The water also powers the

downstream. Since the filling of the reservoir in 2003, the Three Gorges Dam has supplied an extra of fresh water to downstream cities and farms over the course of the dry season. During the South China floods in July 2010, inflows at the Three Gorges Dam reached a peak of , exceeding the peak inflow during the

. The dam's reservoir rose nearly in 24 hours and reduced the outflow to in discharges downstream, preventing any significant impact on the middle and lower river.

Navigating the dam

Locks

The installation of

ship locks A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a chamber in a permanently fixed position i ...

is intended to increase river shipping from ten million to 100 million tonnes annually; as a result transportation costs will be cut between 30 and 37%. Shipping will become 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. Maximum vessel size is 10,000 tons. The locks are 280 m long, 35 m wide, and 5 m deep (918 × 114 × 16.4 ft). That is longer than those on the

St Lawrence Seaway The St. Lawrence Seaway () is a system of rivers, locks, canals and channels in Eastern Canada and Northern United States that permits oceangoing vessels to travel from the Atlantic Ocean to the Great Lakes of North America, as far inland ...

, but half as deep. Before the dam was constructed, the maximum freight capacity at the Three Gorges site was 18.0 million tonnes per year. From 2004 to 2007, a total of 198 million tonnes of freight passed through the locks. The freight capacity of the river increased six times and the cost of shipping was reduced by 25%. Originally, the total capacity of the ship locks was expected to reach 100 million tonnes per year. In 2022, their cargo turnover reached 159.65 million tons, with an annual increase of 6% over the previous few years. These locks are

staircase locks A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a chamber in a permanently fixed position i ...

, whereby inner lock gate pairs serve as both the upper gate of the chamber below and the lower gate of the chamber above. The

gates Gates is the plural of gate, a point of entry to a space which is enclosed by walls. It may also refer to: People * Gates (surname), various people with the last name * Gates Brown (1939-2013), American Major League Baseball player * Gates McFadd ...

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 shiplift is a modern alternative for a slipway, a floating dry dock or a graving dry dock. A shiplift is used to dry dock and launch ships. It consists of a structural platform that is lifted and lowered exactly vertically, synchronously by a ...

, a kind of elevator for vessels. The ship lift can lift ships of up to 3,000 tons. The vertical distance traveled is , and the size of the ship lift's basin is . The ship lift takes 30 to 40 minutes to transit, as opposed to the three to four hours for stepping through the locks. One complicating factor is that the water level can vary dramatically. The ship lift must work even if water levels vary by on the lower side, and on the upper side. The ship lift's design uses a helical gear system, to climb or descend a toothed rack. The ship lift was not yet complete when the rest of the project was officially opened on May 20, 2006. In November 2007, it was reported in the local media that construction of the ship lift started in October 2007. In February 2012, ''

Xinhua Xinhua News Agency (English pronunciation: ),J. C. Wells: Longman Pronunciation Dictionary, 3rd ed., for both British and American English or New China News Agency, is the official State media, state news agency of the China, People's Republic ...

'' reported that the four towers intended to support the ship lift were nearly complete. The report said that by that time, the towers had reached of the anticipated . As of May 2014, the ship lift was expected to be completed by July 2015. It was tested in December 2015 and announced complete in January 2016. Lahmeyer, the German firm that designed the ship lift, said it will take a vessel less than an hour to transit the lift. An article in Steel Construction says the actual time of the lift will be 21 minutes. It says that the expected dimensions of the passenger vessels the ship lift's basin was designed to carry will be . The moving mass (including counterweights) is 34,000 tonnes. The trials of elevator finished in July 2016, the first cargo ship was lifted on July 15; the lift time comprised 8 minutes. ''

Shanghai Daily ''Shanghai Daily'' () is an English-language newspaper founded in 1999 and owned by the Shanghai United Media Group, a state media company under the control of the Shanghai Municipal Committee of the Chinese Communist Party. It was the first dail ...

'' reported that the first operational use of the lift was on September 18, 2016, when limited "operational testing" of the lift began.

Portage railways

Plans also exist for the construction of short

portage railway A portage railway is a short and possibly isolated section of railway used to bypass a section of unnavigable river or between two water bodies which are not directly connected. Cargo from waterborne vessels is unloaded, loaded onto conventional ...

s bypassing the dam area altogether. Two short rail lines, one on each side of the river, are to be constructed. The northern portage railway () will run from the

Taipingxi Taipingxi Town (, "Taiping Stream Town") is a town in Yiling District of Yichang Prefecture-level city of China's Hubei Province. It is located on the left (northern) side of the Yangtze River, near the northern end of the Three Gorges Dam ...

port facility () 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 southern portage railway () will run from Maoping (upstream of the dam) via Yichang South Railway Station to

Zhicheng Zhicheng () is a town in Yidu County-level city, Yichang Prefecture-level city, Hubei Province, China. It is situated on the right (southern) shore of the Yangtze River The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the ...

(on the

Jiaozuo–Liuzhou Railway The Jiaozuo–Liuzhou railway or Jiaoliu railway (), is a major trunkline railroad in China between Jiaozuo in central China and Liuzhou in southern China. The line is long and runs north–south through four provinces.(Chinese焦柳铁路简� ...

). In late 2012, preliminary work started along both future railway routes.

Displacement of residents

During planning, it was estimated that 13 cities, 140 towns and 1,350 villages would be partially or completely flooded by the reservoir, amounting to roughly 1.5% of Hubei's 60.3 million people and

Municipality's 31.44 million people. These 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 Edward Burtynsky (born February 22, 1955) is a Canadian photographer and artist known for his large format photographs of industrial landscapes. His works depict locations from around the world that represent the increasing development of indust ...

documented the impact of the project on the surrounding areas, including the town of

Wanzhou Wanzhou District ( zh, s=万州区 , t=萬州區 , p=Wànzhōu Qū) is Chongqing's second most populated urban core area on the upper reaches of the Three Gorges of the Yangtze River in China. It is currently governed as a district of Chongqing M ...

. Other photographers who recorded the change include Chengdu-based Muge, Paris-based Zeng Nian (originally from Jiangsu), and Israeli

Nadav Kander Nadav Kander HonFRPS (; born 1961) is a London-based photographer, artist and director, known for his portraiture and landscapes. Kander has produced a number of books and had his work exhibited widely. He received an Honorary Fellowship from ...

. Living conditions deteriorated for many, and hundreds of thousands of people could not find work. The older generation was particularly affected, but younger generations benefited from the educational and career opportunities afforded by moving to large cities with new, modern companies and schools. Some 2007 reports claimed that Chongqing Municipality would encourage four million more people to move away from the dam to Chongqing's main urban area by 2020. The municipal government asserted that the relocation was driven by urbanization, rather than a direct result of the dam project, and that the people involved included other areas of the municipality. By June 2008, China had moved 1.24 million residents as far as Gaoyang in Hebei Province, and the moves concluded the following month.

Other effects

Cultural and history

The area which would fill with water behind the dam included locations with significant cultural history. The State Council authorized a ¥505 million archaeology salvage effort. 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. 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. Some sites could not be moved because of their location, size, or design, such as the

hanging coffins Hanging coffins are coffins which have been placed on cliffs. They are practiced by various cultures in China, Indonesia, and the Philippines. China Hanging coffins in China are known in Mandarin as ''xuanguan'' () which also means "hanging co ...

site high in the Shen Nong Gorge, part of the cliffs.

National security

A 2004

United States Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an United States federal executive departments, executive department of the federal government of the United States, U.S. federal government charged with coordinating and superv ...

report stated that "Since Taipei cannot match Beijing’s ability to field offensive systems, proponents of strikes against the mainland apparently hope that merely presenting credible threats to China's urban population or high-value targets, such as the Three Gorges Dam, will deter Chinese military coercion." In response, the

Chinese Ministry of Foreign Affairs The Ministry of Foreign Affairs of the People's Republic of China is the first-ranked Ministries of the People's Republic of China, executive department of the State Council of China, responsible for the country's Foreign relations of China, f ...

criticized the U.S. report as exhibiting a "

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

mentality harbouring evil intentions." The

People's Liberation Army The People's Liberation Army (PLA) is the military of the Chinese Communist Party (CCP) and the People's Republic of China (PRC). It consists of four Military branch, services—People's Liberation Army Ground Force, Ground Force, People's ...

Lieutenant General Liu Yuan cautioned that " twill not be able to stop war. It will have the exact opposite of the desired effect." He also remarked that China would be "seriously on guard against threats from

Taiwan independence Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main island of Taiwan, also known as ''Formosa'', lies between the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of Chi ...

terrorists." Sung Chao-wen, a senior advisory committee member of the Taiwanese

Ministry of Defense A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and military forces, found in states where the government is divided ...

, dismissed online comments about targeting the Three Gorges Dam with missiles as "ridiculous", saying that the dam's high-strength reinforced concrete could withstand a small nuclear weapon, any missile attack would have to penetrate multiple layers of ground and air defenses, and missiles would cause only minimal damage if they reached the dam at all. Zhang Boting, deputy secretary-general of the China Society for Hydropower Engineering, said that the Three Gorges Dam was designed as a concrete

and would therefore be resistant to

nuclear attack Nuclear warfare, also known as atomic warfare, is a military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear warfare can prod ...

s. Debate among Chinese scholars and analysts about the basic principles of China's

no first use In nuclear ethics and deterrence theory, no first use (NFU) refers to a type of pledge or policy wherein a nuclear power formally refrains from the use of nuclear weapons or other weapons of mass destruction (WMD) in warfare, except for as a se ...

(NFU) of nuclear weapons policy includes questions about whether to add narrow exceptions, such as acts that produce catastrophic consequences equivalent to that of a nuclear attack, including attacks intended to destroy the Three Gorges Dam. Nonetheless, supporters of the NFU policy maintain that foreign conventional attacks of such targets including the dam—with the intent to cause mass

civilian casualties A civilian casualty occurs when a civilian is killed or injured by non-civilians, mostly law enforcement officers, military personnel, rebel group forces, or terrorists. Under the law of war, it refers to civilians who perish or suffer wounds ...

and economic losses—are highly improbable.

Structural integrity

Immediately after the reservoir was first filled, around 80 hairline cracks were observed in the dam's structure. Still, an experts group gave the project overall a good-quality rating. The 163,000 concrete units all passed quality testing, with normal deformation within design limits.

Upstream dams

In order to maximize the utility of the Three Gorges Dam and cut down on sedimentation from the

Jinsha River The Jinsha River (, Classical Tibetan, Tibetan: Dri Chu, འབྲི་ཆུ, ) or Lu river, is the Chinese name for the upper stretches of the Yangtze River. It flows through the provinces of the PRC, provinces of Qinghai, Sichuan, and Yu ...

, the upper course of the Yangtze River, authorities are building a series of dams on the Jinsha, including the now completed Wudongde, Baihetan,

Xiluodu The Xiluodu Dam () is an arch dam on the Jinsha River, i.e. the upper course of the Yangtze in China. It is located near the town of Xiluodu in Yongshan County of Yunnan Province but the dam straddles into Leibo County of Sichuan Province on the ...

, and Xiangjiaba dams. The total capacity of those four dams is 38,500 MW, almost double the capacity of the Three Gorges. Baihetan became fully operational in 2022. Wudongde was opened in June 2021. Another eight dams are in the midstream of the Jinsha and eight more upstream of it.

References

{{Authority control Locks of China Gravity dams 2008 establishments in China Dam controversies Dams completed in 2008 Dams on the Yangtze River Energy infrastructure completed in 2012 Hydroelectric power stations in Hubei Underground power stations Yichang Megaprojects