The Three Gorges Dam (simplified Chinese: 长江三峡大坝; traditional Chinese: 長江三峽大壩; pinyin: Chángjiāng Sānxiá Dà Bà) is a Chinese hydroelectric river dam which spans the Yangtze River in Sandouping, Yichang, Hubei, China. As of 2007, it is the largest hydroelectric river dam in the world.
The dam wall is made of concrete and is about 2,335 metres (7,661 ft) long, and 185 metres (607 ft) high. The wall is 115 metres (377.3 ft) wide on the bottom and 40 metres (131.2 ft) wide on top. The project used 28,000,000 m³ (36,600,000 cu yd) of concrete, 463,000 tons

History of the project
When finished, the project will have cost no more than 180 billion yuan (22.5 billion U.S. dollars), 20 billion yuan less than the initial estimated budget of 203.9 billion yuan (25.2 billion U.S. dollars). This calculation accounts for the effect of inflation, and the lower costs are attributed to a low inflation rate in recent years.

Power production
The most significant function of the dam is to control flooding. There are millions of people living downstream of the Three Gorges Dam Project. Many big and important cities like Wuhan, Nanjing and Shanghai were built just beside the river. Plenty of farm land and the most important industrial area of China is built beside the Yangtze River. Flooding is a major problem of a seasonal river like the Yangtze.
In 1954, 47.75 million acres (193,000 km²) of land were flooded, killing 33,169 people and forcing 18,884,000 people to move. The flood covered Wuhan, a city with 8 million people, for over three months, and the Jingguang Railway was out of order for more than 100 days.
In 1998, a flood in the same area caused damage in the range of billions of dollars. The Chinese government asked support from its military to fight against the flooding. Two thousand and thirty-nine square kilometers of farm land was flooded. Over 2.3 million people were affected by the flood and 1526 of them were killed.
The reservoir's flood storage capacity is 22 cubic kilometers (18 million acre feet). This capacity will lessen the frequency of big downstream flooding from once every 10 years to once every 100 years. With the dam, it is expected that major floods can be controlled. If a "super" flood comes, the dam can minimize the impact of it.

Flood control and drought
The installation of ship locks is intended to increase river shipping from 10 million to 50 million tonnes annually, with transportation costs cut by 30 to 37%. Shipping will become safer, since the gorges are notoriously dangerous to navigate. Each ship lock is made up of 5 stages taking around 4 hours in total to complete. Critics argue, however, that heavy siltation will clog ports such as Chongqing within a few years based on the evidence from other dam projects.
The locks are designed to be 280 m long, 35 m wide, and 5 m deep (918 x 114 x 16.4 ft).

Navigation
The relocation of local residents is the central part of the Three Gorges Dam Project. It is considered as important as the construction of the dam. The newly estimated amount of residents need to be relocated is 1.40 million, which is greater than the number estimated (1.13 million)when the project was under planning in early 1990s. It is the largest permanent relocation through out human history. About 140,000 residents will be relocated out of Hubei province to eastern provinces and some central provinces, and the rest majority will be relocated within Hubei Province. On one hand, the relocation shows the Chinese communism government the ability and will to complete the huge project. On the other hand, corruptions and human rights violations occur frequently through out the process. Although most of the residents are properly relocated, there is still significant amount of residents who don't receive enough government aids and still living in poor conditions. Through September 2007, 1.22 million people have been relocated according to the Xinhua Net.This amounts to about 1.3% of the population of the two provinces the reservoir covers. The fourth phase of the relocation is still ongoing. Phase four involves moving people living just below the 175 metre water level. As of 13 October 2007, an estimated 1,400,000 citizens have already been displaced and have settled in neighbouring areas with governmental aid.

Relocation of local residents

Criticism
Currently, the quality of water in the higher banks of Yangtze is falling rapidly, due to the dam's preventing dispersal of pollutants; algae blooms have risen progressively since the dam's construction; and soil erosion has increased, causing riverbank collapses and landslides..
Environmental impact
The 600 kilometre (375 mi) long reservoir will flood some 1,300 archaeological sites and alter the appearance of the Three Gorges as the water level rises over one hundred meters at various locations.

Effect on local culture and aesthetic values
There are two hazards uniquely identified with the dam: Sedimentation
In an annual report to the United States Congress, the Department of Defense cited that in Taiwan, "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."

Future projects upstream

In Max Brooks' novel World War Z, the large artificial lake upstream of the Three Gorges Dam is the site of the initial zombie outbreak before the war. Later in the novel, the Dam is overrun by zombie hordes, which make the emergency pressure release valves impossible to reach. This eventually results in the Three Gorges Dam rupturing, resulting in a massive tsunami which races to the ocean, destroying what remains of Wuhan, Nanjing, and Shanghai.
Jia Zhangke's film, Still Life, describes the destiny of two couples with connections to the dam.
In the novel Dragon Bones by Lisa See, a murder investigation takes place at the Three Gorges Dam.
In the video game Civilization IV Three Gorges Dam is a World Wonder, providing power to the entire continent