Soldiers blew up wooden houses and other debris today in a lake formed by China’s deadly earthquake to speed the flow of water into a diversion channel and ease the threat of flooding for more than 1 million people in the sprawling disaster zone.
The Tangjiashan “quake lake” continued to swell even as water gushed down the spillway built after two weeks of frantic work by engineers and soldiers. Authorities were still on high alert, although the draining operation was progressing smoothly, the official Xinhua News Agency said.
“There is a lot of debris in the upper reaches, and some are quite big, like wooden houses. So now we have asked soldiers to eliminate the debris by using explosives or other means,” Minister of Water Resources Chen Lei told China Central Television.
Soldiers hurled explosives at pieces of splintered wood drifting in one section, according to TV footage. Troops also blasted away boulders in the diversion channel, Xinhua reported.
The Tangjiashan lake, created when a landslide dammed the Tongkou River, has become a priority for a government working to head off another catastrophe even as it cares for millions left homeless from the May 12 quake that killed nearly 70,000 people. More than 1.3 million people live downriver from Tangjiashan, and 250,000 of them have been evacuated.
Though the lake was draining, the effect was barely apparent in the riverside village of Jiuling, about 28 miles downstream, where the turquoise waters of the Tongkou flowed placidly.
“I wish they’d hurry, look at us here,” said rice farmer Cai Yuhua, gesturing at a cluster of mostly home-made tents built on a nearby hillside, where she and hundreds of others waited out the flooding threat.
“The last time we could go back to our homes was May 22. I want to go home and look at my things,” said Mrs Cai, who was living under a striped plastic tarpaulin cast over bamboo poles.
Government experts, quoted by state media, played down the threat of imminent flooding, saying Tangjiashan’s landslide-created dam should hold. But state media and officials estimated it would be a week before the evacuees could return home, even if all goes well.
The official death toll crept up today to 69,136 people, with 17,686 still missing.
The Tangjiashan lake is the largest of more than 30 created by last month’s quake, and draining it safely will depend on controlling the outflow of water, said David Petley, a professor of geography at Durham University.
If water flows too slowly from the lake, pressure will continue to build up behind the dam. If the flow is too fast, it could erode the 1,550-foot (472-meter) drainage channel constructed by the government, creating a steeper, narrower course that would pull in water more rapidly, potentially causing the dam to collapse, Mr Petley said.
“The Chinese government have responded to this in an impressive manner,” said Mr Petley. “I don’t believe that much more could have been done. Unfortunately, the scale of the problem means that management is very challenging.”
Meanwhile, a cargo train derailed in north-eastern Sichuan province early today after being struck by rocks falling from a mountain, Xinhua said. One railway worker was killed and another was seriously injured.
It was not known if the falling rocks were related to the May 12 quake or its aftershocks. The rocks may have been loosened by recent heavy rains, Xinhua reported, citing a Chengdu railway administration official.
Rail traffic was suspended or rerouted, and the damaged line was expected to be repaired in a day.