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Silt becomes problem at Gorges

Chinese construction workers look at the Yangtze River as they take a break at Wushan County, near China's Chongqing Municipality, on Tuesday. PHOTO: REUTERS

Even before the huge reservoir behind China's controversial Three Gorges Dam begins to fill up tomorrow a rescue operation is being launched further upstream to save the river from being choked by silt.

Almost completely ignored so far in China and outside, a new generation of four dams designed to trap the silt before it reaches the Three Gorges, has got the final go-ahead.

Visiting the site on the Jinsha (Golden Sands) river, the Yangtze's longest tributary, the Guardian newspaper has discovered that it lies on the edge of a recognized seismic zone, a potential danger not mentioned in the few published Chinese accounts.

At Xiangjiaba, the site of the dam furthest downstream of the four, construction will take place right on top of a thermal spring that wells up from a mile and a half underground. The dam will displace the thriving Hot Springs resort built only a few years ago, which sits on a bank of the river opposite a canyon.

A statue of a water nymph looms over the swimming pool, the hot baths and the chalets, all dwarfed by the canyon wall. A little way upstream, villagers still wash down their packhorses on a spit of sand.

"The Jinsha has bad geological conditions, and there is a more severe seismic area upriver from Xiangjiaba."

An unnamed Chinese geologist

"It will be just like the Three Gorges -- everything will disappear," said an information officer at the resort headquarters.

"At least we have still got a few years to make some money," the officer said.

The dam height at Xiangjiaba will be 160m: an even larger one upstream at Xiluodu will reach 270m. Work on Xiluodu will begin this year. Both dams are scheduled for completion before 2020. Two smaller dams are also planned.

However, the Jinsha river lies on the edge of a recognized earthquake zone -- identified by the global seismic hazard assessment program -- stretching from the western edge of the Sichuan region to east Yunnan.

"The Jinsha has bad geological conditions, and there is a more severe seismic area upriver from Xiangjiaba," said a Chinese geologist in Sichuan.

He added that near this site, dam projects "should not be encouraged."

China's State Council has given a definitive go-ahead to the project, even though the feasibility studies for Xiangjiaba are "still being written up," according to a statement.

Xiluodu's planned hydro-electric power output of 12,600 megawatts will make it "second in world rank", it was announced in March, equal in size to the Itaipu dam on the Brazil-Paraguay border. The Three Gorges will be the world's largest, with a capacity exceeding 18,000mw.

However, official statements admit that the primary motive is to solve the silt problem facing the Three Gorges Dam. The Jinsha project will be built and funded by the same company responsible for the dam.

"Top officials have a headache," said a report from the Three Gorges headquarters, "how to deal with the problem of sedimentation ... The best way is to build more dams upstream to block the silt from entering the reservoir."

The Jinsha river produces more than half the sediment that will enter the Three Gorges reservoir, at an estimated annual rate of 330 million tonnes. If unchecked this will seriously reduce the reservoir's lifespan and threaten the operation of the dam's turbines. It is claimed that Xiluodu alone will cut the silt deposit by 36 percent.

Objections that the reservoirs behind the four new dams will in turn fill up with silt. There is plenty of "dead storage" room to take care of the sediment, the Three Gorges' manager, Lu Youmei, claimed.

Critics argue that the project is another example of grandiose planning by a powerful political lobby that puts energy first and the environment last.

"It provides the [Three Gorges] project corporation with another golden opportunity to develop, so that it can become a power giant in China," said Mu Lan, editor of the Toronto-based Three Gorges Probe research project.
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