China's Weather-Changing Three Gorges Dam

The myth that the Great Wall of China is visible from the moon was disproved long ago, but the country's Three Gorges Dam -- sometimes called the next Great Wall -- is one of the few man-made structures actually visible to the naked eye from space. Even clearer will be the dramatic transformation the world's largest hydroelectric power generator will have on the Yangtze River and the surrounding landscape. Now NASA, which has been following the development of the socially and environmentally controversial dam via satellite since 1987, gives us an idea of what those changes are looking like with this new animation.

Most interestingly, the larger mass of water created by the dam beginning in June 2003 -- the river was one-third of a mile in width before becoming a 401-square-mile reservoir -- has led to a particularly strong "lake effect." That means cooler temperatures and increased rainfall between nearby mountains, but less rainfall in the immediate vicinity of the reservoir.

...researchers were surprised to see that the dam affected rainfall over such a large area - a 62-square-mile region - rather than just 6 miles projected in previous studies.

The other numbers are ever mind-boggling: the $625 billion dam is roughly 1.4 miles (2.3 kilometers) long and 607 feet tall, five times larger than Hoover Dam on the Arizona-Nevada border, and, when all 26 turbines become operational in 2009, it will be able to produce 18,000 megawatts of electricity, twenty times the power of Hoover Dam. The reservoir will also make it possible for 10,000-ton freighters to enter China's interior, opening a region burgeoning with agricultural and manufactured products, and increasing commercial shipping access to China's cities.

The project also features a few more controversial numbers: it will submerge about 244 square miles (393 square kilometers) of land, which includes the three gorges that give the dam its name (the Qutang, Wu Xia, and Xiling) and dozens of architectural and cultural sites. More than 1 million people will have been relocated by the dam's completion.

No doubt, the area is in desperate need of flood control, just as the country is in need of cleaner energy than coal. During the 20th century, officials estimate that some 300,000 people were killed from floods on the Yangtze. The dam is designed to greatly improve flood control on the river and protect the 15 million people and 3.7 million acres of farmland in the lower Yangtze flood plains.

But concerns have grown about pollution in the reservoir, due to pesticides, fertilizers and sewage. Meanwhile, a joint study by the Chinese Academy of Sciences, the World Wildlife Fund and the Yangtze River Water Resources Commission, found that nearly 30 percent of the Yangtze's major tributaries were seriously polluted.

While it may still be too early to make pronouncements about the environmental impacts of the Three Gorges Dam, it already stands as a twin symbol of the Chinese government's power, both for the good of the earth and the bad. Like the one-child policy, the Grain-to-Green program, and the "green wall" of China, this super-project proves that China can play a strong and potentially positive role in shaping its environmental future; its strong dependence on coal, its still weak ability to address pollution on a local level and its low spending on education are examples of dangerous negligence.

Just as important as the symbolism of the Dam is the legacy the project has left for Chinese society. While the Three Gorges was proposed at a time when the public generally accepted government projects, the subsequent controversy, particularly over mass relocation of residents--and a spate of highly-publicized ecological dangers--has altered the dialog between government and the people, with positive implications for the environment. As Southern Weekend journalist Jianqiang Liu wrote at Worldwatch recently,

The environmental movement has forced China to depart from the "Three Gorges Dam era." Today, the public has more power to fight against special interest groups, hinder government decisions, and even change interest patterns while protecting their rights. The Chinese have chosen environment protection as a more moderate but complicated way of approaching democracy.

Animation courtesy NASA/Goddard Space Flight Center, Scientific Visualization Studio, United States Geological Survey, via NASA

Also see China's Green Revolution, The World's Largest Subway and Edward Burtynsky's Manufactured Landscapes

Tags: China