China's Three Gorges Dam: Benefits, Controversy, and Impact

Overview of the Three Gorges Dam Project

The Three Gorges Dam Project (TGP) is the world's largest hydropower complex. It is situated in the Xilingxia Gorge — one of the three gorges of the Yangtze River — in Hubei Province, China. The gorge controls approximately 1 million km² of drainage area and averages a runoff of 451 billion m³ annually. The China Three Gorges Corporation (CTGPC) acts as the legal entity for the TGP and is responsible for the financing, construction, and operation of the dam. Construction was completed in 2008. The dam stands 185 meters high and 2,309 meters wide, making it the world's largest hydroelectric plant (Bristow, 2007).

The Three Gorges Dam project involves harnessing the Yangtze River — Asia's longest river — to generate enormous amounts of electricity. Output was projected at approximately 85 TWh per year, close to one-tenth of China's electricity requirements at the time. A further purpose of the dam is to end catastrophic flooding downstream, which over the years has claimed many lives. Improved navigability on the river is also expected to allow much larger ships to sail from Shanghai as far as Chongqing — upstream from the dam and approximately 2,000 km from the sea — supporting China's growing domestic and export trade.

The dam is positioned 44 km from the city of Yichang in Hubei Province, at the end of a series of steep canyons. This location forms a 630 km reservoir with an average width of 1.3 km. The plant sits at the center of a broader plan for central China's electricity sector. Associated transmission and distribution systems are linked to three regional grids that together constitute the Three Gorges power network, forming a single system stretching from the coast to the border of Tibet. The planned shares of power offtake among the grids are: Central China Power Network (55%), East China Power Network (39%), and Sichuan Provincial Grid (6%) (Bristow, 2007).

Power Generation and Transmission Infrastructure

A total of 26,700 MW of power generators were installed — 14 sets on the left bank and 12 sets on the right. They became operational in October 2008 and generated a combined 18,200 MW. Subsequently, six additional generators were installed underground, bringing the total to 32 sets. These final six were expected to become fully operational by 2011. In September 2009, the project demonstrated its power-generation capacity by producing 348.4 TWh of electricity, equivalent to approximately one-third of the project's total cost. By the end of 2009, it was expected to generate 150,000 GWh more than the originally planned 224,400 GWh, for a total of 370,000 GWh (Bristow, 2007).

The TGP power distribution and transmission infrastructure was completed in December 2007. Power from the dam is transferred to two cities and nine provinces via three transmission corridors. A 500 kV DC transmission line to the East China Grid carries a capacity of 7,200 MW; a 500 kV DC line to the South China Grid carries 3,000 MW; and a 500 kV AC line to the Central China Grid carries 12,000 MW. The East China Grid is specifically served by three 500 kV DC lines: the HVDC Three Gorges–Changzhou line (3,000 MW), the HVDC Three Gorges–Shanghai line (3,000 MW), and the HVDC Gezhouba–Shanghai line (1,200 MW) (Three Gorges Dam Hydroelectric Power Plant, China, 2010).

According to China's leaders, the dam provides the foundation for the nation's future economic prosperity. Beyond electricity, the reservoir enables 10,000-ton freighters to travel into China's interior — a route previously limited to vessels under 1,500 tons. Ships can navigate from Shanghai to Chongqing, roughly 2,000 km from the sea. The dam has also been promoted as a tourist attraction, with tour boats offering scenic trips on the reservoir. In addition, the government notes that the dam's power generation potential of 84.7 billion kWh per year is the energy equivalent of burning 50 million tons of coal or 25 million tons of crude oil. "The switch to cleaner hydroelectric power would have the effect of cutting 100 million tons of carbon dioxide, up to two million tons of sulfur dioxide, ten thousand tons of carbon monoxide, 370,000 tons of nitrogen oxide, and 150,000 tons of particulates annually from the atmosphere" (Cleveland, 2008).

Environmental Concerns and Ecological Impact

The long-term ecological consequences of the dam have been described as potentially catastrophic. The dam disrupts profound silt flows in the river. It is believed that rapid silt buildup in the reservoir could create an imbalance upstream while depriving agricultural land and fisheries downstream of necessary nutrients. Because these problems would also affect the plant's turbines as well as millions of farmers and fishermen, it is necessary to consider the ecology of the entire river system.

Opposition from both environmentalists and politicians to the Three Gorges Dam has been intense. Local farmers, environmental campaigners, and even some officials have all raised concerns about environmental damage, including landslides that have produced waves as high as 50 meters on the reservoir. Despite these widespread reports, the Chinese central government has insisted that there are no geological irregularities. Critics have long argued that the project was likely to cause environmental harm in the areas surrounding the reservoir. Farmers living near the 660 km long, 1.1 km wide reservoir have described landslides caused by the immense weight of water and fluctuations in water level, as well as tremors that have left cracks in the walls of their homes (Bristow, 2007).

China continues to insist that no unforeseen environmental problems have occurred. Although it has not ruled out the possibility of natural disasters in the future, the government has stated that there will be no major damage to life or property. Officials have claimed that silt levels behind the dam are less than half of anticipated levels, that algae blooms in waterways supplying the reservoir have been controlled, that rare flora and fauna have been protected, and that the risk of reservoir-induced earthquakes is low (Bristow, 2007).

A recent study by the Chinese Academy of Sciences found that water quality in the Three Gorges reservoir areas continues to decline, which is causing fish stocks to fall. At the 3rd Yangtze Forum in Shanghai, China announced plans for 20 additional dams on the headwater tributaries of the Yangtze River, including the Yalong (Nyachu in Tibetan), Dadu (Gyarong Ngulchu), and Wujiang rivers (McDermott, 2005). Chinese officials have indicated that by 2020 approximately 50% of the Yangtze's hydropower resources will be tapped — up from about 36% at the time of the announcement — and that by 2030 about 60% of the river's electricity-producing potential will be harnessed. It is further believed that by 2030 more than 30% of the Yangtze's water resources will be used for agriculture or industry, up from 17.8%, in a region likely to experience decreasing rainfall due to climate change (McDermott, 2005).

Conclusion

The environmental effects of the Three Gorges Dam project cannot be overlooked, but nor can the benefits it has brought to the country. Power and electricity are vital to the health of the people as well as to their overall survival as a nation. There are many lessons that China has learned from this project. It needs to take heed of these lessons as it moves forward with additional dam construction. China also needs to address any environmental issues that still remain from the construction of this dam, so that citizens know their government is committed to acting in their best interests as development continues.

References

Bristow, M. (2007). Deep concern over Three Gorges Dam. BBC News. Retrieved May 6, 2010, from http://news.bbc.co.uk/2/hi/asia-pacific/7120856.stm

Cleveland, C. J. (2008). Three Gorges Dam, China. Retrieved May 20, 2010, from The Encyclopedia of Earth:

McDermott, M. (2005). China wants 20 more dams on the headwaters of the Yangtze River. Retrieved May 6, 2010, from

Three Gorges Dam Hydroelectric Power Plant, China. (2010). Retrieved May 20, 2010, from Power Technology: http://www.power-technology.com/projects/gorges/