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China fills Three Gorges Dam

The Three Gorges Dam on China’s Yangtze River has closed its gates after more than 10 years construction. Dam officials filled the reservoir to an interim level of 443 feet on June 10, five days ahead of schedule. Ultimately, the dam water will submerge 312 million square feet of land, taking 13 cities, 140 towns and more than 1,000 villages. Scientists and engineers following the project have greeted the rising reservoir of the world’s largest hydroelectric project with mixed emotions.

When complete in 2009, the $25-billion dam will be capable of generating 18,200 megawatts of energy from 26 turbines, each with an output of a medium-sized nuclear reactor. Beginning this August, the dam will provide electricity to Shanghai and six other provinces of China. Harnessing the Yangtze is a clean solution to China’s power shortage, dam proponents say, whereas fossil fuels such as coal, are responsible for the annual exhaust of 120 million tons of carbon dioxide and 2 million tons of sulfur dioxide, according to the June 13 China Daily.

Proponents also hail the Three Gorges project for its ability to control Yangtze’s cyclic floods, fatal to 300,000 in just the last century. Still, hydrologists say local flooding at the lower reaches of the river will persist. And opponents of the dam point to the displacement of more than one million people and loss of biodiversity.
The government has pledged sustaining the livelihoods of displaced people as a top priority, says Kamran M. Nemati, professor of civil engineering at the University of Washington and leader of a delegation to China to exchange technical information about the dam. “For every dollar spent on construction, a dollar is being spent on relocating dam-affected persons,” he says. However, critics say the rural poor do not meet government criteria for compensation.

The dam will diminish the Three Gorges, a famed series of canyons along the Yangtze, and will swallow several archaeological sites. In addition, the millions of tons of waste people pour into the Yangtze annually may accumulate in stagnant reservoir waters.

“China needs electricity. But rather than building one giant dam, China could have built between six to 10 smaller dams along the Yangtze’s tributaries. This would have had a smaller environmental and social impact,” says Vaclav Smil, professor of geography at the University of Manitoba in Canada and an expert on China’s energy and environment. “Moreover, any problem you could have with a small dam will be vastly magnified in the case of the Three Gorges.”

The dam could face two main geological hazards, Smil says: siltation and earthquakes. A dam along the muddy waters of the Yangtze could be particularly prone to siltation, the buildup of sediment in the reservoir behind the dam. “The dam will need constant dredging to remove sediment buildup, a huge financial cost,” Nemati says.

The Chinese have taken steps to minimize siltation by vegetating slopes surrounding the Yangtze. Nevertheless, deforestation along the Yangtze will increase erosion, causing the dam to silt much faster than the specified rate, Smil says.

Located in a seismic zone, the Three Gorges is also at risk for earthquakes or rockslides that could rupture the dam or cause a water surge. Some researchers have suggested that the pressure of the dam’s massive water reservoir on underlying strata could lead to earthquakes. Geologists report that the strongest possible quake in the dam area is a magnitude 5.2. “The dam is designed to withstand a [magnitude] 7.0,” Nemati says. “The Chinese have done their homework before building the dam.”

Although the Three Gorges Dam is expected to boost China’s economy and improve the standard of living, many wonder whether the benefits are worth the costs. “It will be difficult to find new farmland for migrants,” Smil says. “Many will have nowhere to go.”

Neeta Bijoor
Geotimes contributing writer


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