In China, New Risks Emerge At Giant Three Gorges Dam

serynade

RESERVOIR OF FEAR
In China, New Risks Emerge
At Giant Three Gorges Dam

Scientists Spot Dangers
In Slides, Silt and Algae;
Cracks in a Rice Paddy

By SHAI OSTER
August 29, 2007; Page A1

MIAOHE VILLAGE, China -- China's vaunted engineeringmarvel, the Three Gorges Dam, drew fierce criticism during itsconstruction for uprooting more than a million people and manhandlingthe Yangtze River basin. Now, a year after completion, the project hasnew problems -- including landslides, water pollution and suggestionsthat the dam could contribute to the very flooding it was built toprevent.

Geologists say the massive weight of water behind theThree Gorges Dam has begun to erode the Yangtze's steep shores atseveral spots. That, along with frequent fluctuations in water levels,has triggered a series of landslides and weakened the ground underplaces like Miaohe, a village about 10 miles up the reservoir from thedam. Local officials worry that a whole mountainside here couldcollapse into the water, killing residents and threatening a vitalshipping lane.

There are additional dangers. Chinese scientists saythat as the dam blocks silt heading downstream, the Yangtze Riverestuary region, which includes Shanghai, is shrinking and sea water iscoming further inland. A report this spring by the World WildlifeFederation said water flowing through the dam is now moving faster,damaging downriver dikes. The urbanization that accompanied the dam'sconstruction led to more raw sewage and fertilizer runoff, whichcollects in the reservoir rather than flushing downstream.

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

Questions about the Yangtze are taking on addedurgency as China grapples with a mounting water shortage. Across thecountry, millions of tons of raw sewage, industrial waste andfertilizer runoff have turned lakes into algae-covered cesspools.According to official statistics, more than half of China's majorwaterways are so polluted that fish are dying or water is unsafe fordrinking or irrigation. More than 300 million people -- almostone-quarter of the population -- lack access to clean drinking water,the government says.

Making thingsworse, more than one-third of the country's 85,000 or so reservoirshave "serious" structural problems, according to the official Xinhuanews agency. This spring, a deputy minister of water resources calledChina's reservoirs "time bombs" that could threaten the lives andproperty of those downstream. In 1975, a dam collapse in Henan provincekilled tens of thousands or more, an incident that was covered up untilrecently.

China's media is starting to cover problems at ThreeGorges Dam and its 400-miles-long reservoir. The government hasn'tspoken publicly about issues here, but it has quietly rolled out awarning system for landslides and is supporting research to map outat-risk regions. Officials are pouring money into water-treatmentplants and reinforcing about 1,400 miles of riverbanks.

'More Serious'

"We thought of all the possible issues," saysenvironmental scientist Weng Lida, the former head of the Yangtze RiverWater Resources Protection Commission, a government agency tasked withprotecting the river basin's water and environment. He is now secretarygeneral of the Yangtze River Forum, a coalition of the Chinesegovernment and nongovernmental organizations that share research on theregion's environment. "But the problems are all more serious than weexpected."

The government agency that oversees the dam, the Changjiang Water Resources Committee, declined requests for an interview.

The changes can be seen here in Miaohe, wherevillagers have grown oranges from gnarled trees and farmed the area'ssteeply terraced rice paddies for generations. Miaohe's 100 or soresidents narrowly avoided the mass relocations that accompanied thedam's construction, when some 1.3 million people moved from their homesto make way for the reservoir.

This spring, villagers noticed a crack some 600 feetlong and barely a half-inch thick zigzagging across their paddies. Notlong afterward, dam officials lowered reservoir levels to prepare forthe 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. Thegovernment told them to evacuate.

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

The 4,000-mile long Yangtze is the world'sthird-longest river, racing down from Tibetan glaciers, slicing massivevalleys through the middle of China and passing fertile plains beforeits brown waters meet the sea. On the way, the river passes the ThreeGorges, a series of canyons that for centuries plagued sailors withswift 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 inpart to harness its power, but primarily to prevent catastrophicflooding. Modern China's founding father, Sun Yat-sen, proposed a damin 1919. Mao Zedong, who believed nature could be shaped to man'spurpose, wrote a poem about turning the treacherous Three Gorges into anavigable lake.

From the late 1950s, the government approved and thendelayed construction of a dam here several times, hobbled by technicalchallenges. By the late 1980s, China also faced mounting charges that adam and reservoir would force mass relocations and destroyarcheological sites and temples.

In April 1989, the government responded to criticism,saying it would delay a decision for at least five years. But opponentswere silenced in the aftermath of Tiananmen Square crackdown in a fewmonths later. In 1992, scientists and engineers completed a finalenvironmental feasibility study. Later that year, the dam project wasput to a vote before the National People's Congress. It passed. Butnearly one-third of China's usually docile legislature voted no orabstained, an unusual show of dissent.

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

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

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

With a final cost of at least $22 billion, the600-foot-tall dam was finished in May 2006. Once it is fullyoperational later this year, it will contain five trillion gallons ofwater, equivalent to one-fifth of the fresh water consumed each year inthe U.S. It will produce more than 18,000 megawatts of electricity,nearly 10 times the capacity of Hoover Dam.

Filling With Sewage

Mr. Weng, the environmental scientist, believes thedam was necessary to stop floods. His biggest concern now is theworsening quality of the reservoir's water. Phosphorus and nitrogenlevels from industrial and fertilizer runoff have risen 10 times abovelevels 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 thandoubling from 2000 to 2005, the WWF report says. The basin is home tosome 160 million people, including 30 million in the municipality ofChongqing, 400 miles upstream from the dam. In the 10 years ending in2005, the Yangtze basin economy grew 12.6% a year on average -- apercentage point faster than the rest of the nation -- as it hasswitched from agriculture to industry.

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

From the beginning, engineers were also concernedabout sedimentation. The Yangtze carries some 500 million metric tonsof silt into the gorges each year. Without a way to release most ofthis mud, the reservoir would silt up and the dam could breach orcollapse. Government engineers created 23 sluice gates at the bottom ofthe dam to release turbid water during flood season, and they estimatethe system will keep the reservoir at roughly 90% or more of itscapacity for nearly a century. Some critics believe sedimentation isgrowing at a faster rate, which could eventually make the dam unable tocontain a flood crest.

Downstream, fluctuating sediment levels pose yet adifferent problem. In water with little sediment, sunlight reachesdeeper and nourishes the photosynthetic algae, which also feeds onsewage and fertilizer runoff, Mr. Weng says.

Mr. Zhou, the reservoir management vice director, saysthe dam is not responsible for the blooms. Algae had turned out to beless of a concern than the Three Gorges committee had expected, hesays, with only minor blooms in Yangtze tributaries.

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

Critics say that while the dam can handle surges, itmay contribute to downstream flooding for an unforeseen reason. Pastthe narrow gorges where it enters central China's broad plains, theriver traditionally slowed, and in some places centuries ofsedimentation raised the riverbed above the surrounding countryside andis held back by dikes, as in New Orleans. Water released by ThreeGorges runs faster, the WWF says, because the dam traps most of thesilt. Lightened of its muddy load, the water courses out with moreforce and threatens to gouge out these dikes.

Geologists, meanwhile, are focusing on landslides. TheThree Gorges have a base of limestone but are layered in places withsandstone, shale and mudstone -- softer materials that are more likelyto collapse. Some areas were reinforced before the reservoir wasfilled. But as dam officials raise and lower water levels inanticipation of floods, the soaking and huge pressure changes leavebanks weakened.

A team of scientists at the Imperial College Londonsaid earlier this year that slope instability is the gorges' "mostwidespread natural hazard." Writing in the Quarterly Journal ofEngineering Geology and Hydrogeology, published by the GeologicalSociety of London, they warned the problem is likely to get worse.

The Dowry Plan

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

A spokesman for China's Ministry of Land Resourcesblames this year's high incidence of landslides on heavy rainfallssince spring. He says the early-warning system has detected some majorslides and that the government is training local people to recognizelandslide warning signs.

Less than a mile from Miaohe, where a gravel road thatprovides sole access to the village passes through a muddy tunnel, thevillagers have set up temporary housing. Inside the tunnel, they campin plastic lean-tos. Nearby, the local government is clearing an areafor the refugees to build new homes.

The government is providing money for homes, but thevillagers 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. Thelocal government is providing families a dowry for their daughters, toencourage them to marry out.

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

--Zhou Yang and Kersten Zhang in Beijing contributed to this article.