Flood control and drought relief
The most significant function of the dam is to control flooding, which is a major problem of a seasonal river like the Yangtze. Millions of people live downstream of the dam, and many large and important cities like Wuhan, Nanjing and Shanghai lie next to the river. Plenty of farm land and the most important industrial area of China are built beside the river.
In 1954, the river flooded 47.75 million acres (193,000 kmÂ²) of land, 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 to the value of billions of dollars. The Chinese government asked for support from its military to fight the flooding. Two thousand and thirty-nine square kilometers of farm land was flooded. The flood affected more than 2.3 million people, and 1,526 were killed.
The reservoir's flood storage capacity is 22 cubic kilometers (18 million acre feet). This capacity will reduce the frequency of major 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 is expected to minimize its effect.
The electricity generated by the Three Gorges Dam project is sold to the State Grid Corporation and China South Power Grid Corporation at a rate of Â¥250 per MWh ($32.5 US). Nine provinces and two cities consume the power from it, including Shanghai.
The power distribution and transmission of the Three Gorges Dam project cost about 34.387 billion Yuan. It was completed in December 2007, one year ahead of time.
Power is sent in three directions. The 500 kV DC transmission line to the East China Grid has a capacity of 7,200 MW. There are three 500 kV DC transmission lines: HVDC Three Gorges-Shanghai(3,000 MW), HVDC Three Gorges-Changzhou(3,000 MW) and HVDC Gezhouba - Shanghai(1,200 MW). The 500 kV AC transmission line to Central China Grid has a capacity of 12,000 MW. The other 500 kV DC transmission line HVDC Three Gorges-Guangdong to South China Grid has a capacity of 3,000 MW and supplies Guangdong.
In the original plan, it was expected to provide 10% of electricity consumption in China. However, China?s demand for electricity has increased at a higher rate than was planned, and if fully operational now, it would support about 3% of the total electricity consumption in China.
Relocation of local residents
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. During the planning stages in the 1990s, it was estimated that 1.13 million residents would be forced to relocate, new developments have doubled that number to 2.3 million. That estimate has been increased and as of 13 October 2007, 1,400,000 citizens...