Three Gorges Dam, Enviro-Disaster

♠ Posted by Emmanuel in , at 8/29/2007 08:35:00 PM
If I were a conspiracy theorist, I'd be citing the recent boom in Chinese product safety and pollution stories in the American media as a coordinated effort to defame the Middle Kingdom. China has already suggested that the product safety issue serves this purpose. However, as I am not a conspiracy theorist, I'll pluck the more interesting stories about those two issues here. You may recall the furor over the construction of the Three Gorges Dam from not so long ago. The mother of all megadams was supposed to alleviate water scarcity, control flooding, and provide hydroelectric power.

According to today's Wall Street Journal, however, the dam is falling short of these goals. On top of that, it is adding all sorts of additional problems that are mostly of the environmental variety. I always was critical of the cultural and social damage that the dam would cause, but it turns out there are environmental issues which may render those concerns as secondary, hard as it is to believe. Siltation, landslides, water name a damming (pun intended) issue, and the Three Gorges has it:
China's vaunted engineering marvel, the Three Gorges Dam, drew fierce criticism during its construction for uprooting more than a million people and manhandling the Yangtze River basin. Now, a year after completion, the project has new problems -- including landslides, water pollution and suggestions that the dam could contribute to the very flooding it was built to prevent.

Geologists say the massive weight of water behind the Three Gorges Dam has begun to erode the Yangtze's steep shores at several spots. That, along with frequent fluctuations in water levels, has triggered a series of landslides and weakened the ground under places like Miaohe, a village about 10 miles up the reservoir from the dam. Local officials worry that a whole mountainside here could collapse into the water, killing residents and threatening a vital shipping lane.

There are additional dangers. Chinese scientists say that as the dam blocks silt heading downstream, the Yangtze River estuary region, which includes Shanghai, is shrinking and sea water is coming further inland. A report this spring by the World Wildlife Federation [sic] said water flowing through the dam is now moving faster, damaging downriver dikes. The urbanization that accompanied the dam's construction led to more raw sewage and fertilizer runoff, which collects in the reservoir rather than flushing downstream.

The emerging issues at Three Gorges illustrate this rapidly industrializing country's efforts to control its environment, and how the attempts to overcome them can worsen the problem. In other areas of the world, dam building has resulted in landslides or earthquakes set off by the weight of water in reservoirs. Here at the world's largest hydroelectric project, a center of China's population and economy, the consequences could be magnified...

China's media is starting to cover problems at Three Gorges Dam and its 400-miles-long reservoir. The government hasn't spoken publicly about issues here, but it has quietly rolled out a warning system for landslides and is supporting research to map out at-risk regions. Officials are pouring money into water-treatment plants and reinforcing about 1,400 miles of riverbanks.

"We thought of all the possible issues," says environmental scientist Weng Lida, the former head of the Yangtze River Water Resources Protection Commission, a government agency tasked with protecting the river basin's water and environment. He is now secretary general of the Yangtze River Forum, a coalition of the Chinese government and nongovernmental organizations that share research on the region's environment. "But the problems are all more serious than we expected..."

The changes can be seen here in Miaohe, where villagers have grown oranges from gnarled trees and farmed the area's steeply terraced rice paddies for generations. Miaohe's 100 or so residents narrowly avoided the mass relocations that accompanied the dam's construction, when some 1.3 million people moved from their homes to make way for the reservoir.

This spring, villagers noticed a crack some 600 feet long and barely a half-inch thick zigzagging across their paddies. Not long afterward, dam officials lowered reservoir levels to prepare for the summer flooding season.

After early May rains raised reservoir levels again, there were four landslides in five days not far from Miaohe village. Villagers say they heard timbers in their houses begin to split. The government told them to evacuate.

Officials in Zigui City, the county seat, are facing a new wave of relocations. Some 100,000 people in the county moved to make way for the reservoir. Now officials are concerned they'll have to relocate more. "The changes have come faster than our plans," said Cui Shaofeng, an official from the Zigui County resettlement office.

The 4,000-mile long Yangtze is the world's third-longest river, racing down from Tibetan glaciers, slicing massive valleys through the middle of China and passing fertile plains before its brown waters meet the sea. On the way, the river passes the Three Gorges, a series of canyons that for centuries plagued sailors with swift currents and hidden rocks. Floods were a constant threat, claiming 300,000 victims, by some estimates, in the last century alone.

China's leaders long dreamed of damming the Yangtze in part to harness its power, but primarily to prevent catastrophic flooding. Modern China's founding father, Sun Yat-sen, proposed a dam in 1919. Mao Zedong, who believed nature could be shaped to man's purpose, wrote a poem about turning the treacherous Three Gorges into a navigable lake...

Construction officially began in 1994. Controversy continued. Responding to pressure from human-rights groups, the U.S. government and the World Bank pulled support from the project. In an open letter in 2000, leading engineers in China, including some who had worked on the feasibility study, protested a decision to fill the reservoir faster than originally planned.

The first trouble came in June 2003, two weeks after the Yangtze River was impounded and the reservoir began to fill. While water levels rose, passing 300 feet and approaching 450 feet, the valley's slopes started eroding under the pressure of the water.

On July 14, a mountain on a tributary of the Three Gorges gave way, shearing a tongue of land about two-thirds of a mile wide and long and more than 60 feet thick. Thirteen farmers were swept to their deaths in the mud and debris. The wedge hit the water, sending a two-story-tall wave crashing over 20 boats, drowning 11 fishermen. Officials blamed the landslide on heavy rainfall. Geologists say a sudden change in water levels loosened rocks along the riverbanks.

With a final cost of at least $22 billion, the 600-foot-tall dam was finished in May 2006. Once it is fully operational later this year, it will contain five trillion gallons of water, equivalent to one-fifth of the fresh water consumed each year in the U.S. It will produce more than 18,000 megawatts of electricity, nearly 10 times the capacity of Hoover Dam.

Mr. Weng, the environmental scientist, believes the dam was necessary to stop floods. His biggest concern now is the worsening quality of the reservoir's water. Phosphorus and nitrogen levels from industrial and fertilizer runoff have risen 10 times above levels a decade ago, according to the WWF report, which he co-edited.

The reservoir is filling with sewage as well. Waste-water discharge has soared in the Yangtze basin, more than doubling from 2000 to 2005, the WWF report says. The basin is home to some 160 million people, including 30 million in the municipality of Chongqing, 400 miles upstream from the dam. In the 10 years ending in 2005, the Yangtze basin economy grew 12.6% a year on average -- a percentage point faster than the rest of the nation -- as it has switched from agriculture to industry.

Scientists and government officials say many sewage plants were built to process waste before it hits the reservoir, but that some aren't connected to city drains. Zhou Wei, vice director of the department of reservoir management at the government's Three Gorges Project Construction Committee, acknowledges that sewage levels in the reservoir appear to be increasing. He says the government has given additional funds to make sure plants are running full-time.

From the beginning, engineers were also concerned about sedimentation. The Yangtze carries some 500 million metric tons of silt into the gorges each year. Without a way to release most of this mud, the reservoir would silt up and the dam could breach or collapse. Government engineers created 23 sluice gates at the bottom of the dam to release turbid water during flood season, and they estimate the system will keep the reservoir at roughly 90% or more of its capacity for nearly a century. Some critics believe sedimentation is growing at a faster rate, which could eventually make the dam unable to contain a flood crest...

There are also concerns about whether the dam will control floods. Weeks of downpours in July created the biggest surges on the upper Yangtze since 1998, when flooding on the undammed river killed thousands downstream. Officials announced on Aug. 1 that the July crest passed through the dam without incident.

Critics say that while the dam can handle surges, it may contribute to downstream flooding for an unforeseen reason. Past the narrow gorges where it enters central China's broad plains, the river traditionally slowed, and in some places centuries of sedimentation raised the riverbed above the surrounding countryside and is held back by dikes, as in New Orleans. Water released by Three Gorges runs faster, the WWF says, because the dam traps most of the silt. Lightened of its muddy load, the water courses out with more force and threatens to gouge out these dikes.

Geologists, meanwhile, are focusing on landslides. The Three Gorges have a base of limestone but are layered in places with sandstone, shale and mudstone -- softer materials that are more likely to collapse. Some areas were reinforced before the reservoir was filled. But as dam officials raise and lower water levels in anticipation of floods, the soaking and huge pressure changes leave banks weakened.

A team of scientists at the Imperial College London said earlier this year that slope instability is the gorges' "most widespread natural hazard." Writing in the Quarterly Journal of Engineering Geology and Hydrogeology, published by the Geological Society of London, they warned the problem is likely to get worse.

One of the authors looked at satellite readings of Zigui, Wushan and Badong counties, with a combined population of more than a million people. Geologist Ioannis Fourniadis of Imperial College London estimated that 3% of the counties' slopes are actively falling and 7% are unstable for activities such as road building. Another 15% were mostly stable. The rest were solid limestone, which he says pose extremely low risk.

A spokesman for China's Ministry of Land Resources blames this year's high incidence of landslides on heavy rainfalls since spring. He says the early-warning system has detected some major slides and that the government is training local people to recognize landslide warning signs.

Less than a mile from Miaohe, where a gravel road that provides sole access to the village passes through a muddy tunnel, the villagers have set up temporary housing. Inside the tunnel, they camp in plastic lean-tos. Nearby, the local government is clearing an area for the refugees to build new homes.

The government is providing money for homes, but the villagers say it isn't enough. The farmers will be able to grow rice, oranges and tea here, but they complain that the land isn't good. The local government is providing families a dowry for their daughters, to encourage them to marry out.

"This all started happening right after they began damming the river," says Han Qingxi, 52 years old, pausing from rebuilding his simple stone home. Nearby, backhoes level the mountainside. "They say it's safer here," he says.