China drains quake-formed lake, as engineers and weary evacuees watch warily

June 2008

U.S. Water News Online

MIANYANG, China — Water flowed slowly into a manmade spillway from a swollen lake formed by a landslide during China's devastating earthquake, easing the immediate threat of a flood that prompted the evacuation of more than 250,000 people.

Engineers were monitoring bridges and river banks downstream to see if they would hold, and
work crews were trying to dig a secondary channel to improve the draining, China Central Television and the Xinhua News Agency reported.

Though experts said the potential for flooding remained, the government seemed relieved, and people evacuated to cramped camps for safety anticipated going home.

“I wish the water would hurry up so we can go home,” said Wang Jing, a 25-year-old nurse packed with an estimated 9,500 others into the branch campus of the Sichuan Music School in Mianyang city.

Waters had been building up behind the landslide for nearly four weeks, creating a massive lake that had to be drained carefully to prevent a surge. Even after the draining began, water levels continued to rise but more slowly, appearing to stabilize around a level the government said was unlikely to undermine the landslide-created dam.

“Emergency work is still proceeding urgently, but in the foreseeable future there's no risk of the dam collapsing,” Xinhua quoted Chengdu Military Region Deputy Commander Fan Xiaoguang as saying.

Collapse of the quake-formed lake, known as Tangjiashan, could flood an area home to 1.3 million people in hilly central Sichuan province and compound the misery in a disaster zone still reeling from the May 12 quake that killed nearly 70,000 people. While 250,000 people were already evacuated, plans were in place to move a million more.

“I can't even cry, even if I want to. First it was the earthquake, now it's floods,” said Yu Taichun, a doctor who was keeping watch over a small medical center in a tent city of about 2,500 people on the forested slopes of Taohua, or Peach Blossom, Mountain.

Yu said he has moved five times since the quake, arriving about two weeks ago at the latest camp overlooking the town of Qinglian, about 20 miles (30 kilometers) downstream from Tangjiashan.
Nerves were frayed among the refugees, who had little to do except wait for updates on the lake — the largest of more than 30 that have formed behind landslides.

Heatstroke was becoming a problem in the camp, where temperatures in the tents would often top 100 degrees, Yu said. Trucks delivered water several times a day, but there were no shower facilities and toilets were backed up.

Despite rising impatience and weariness, state media and government officials said refugees who had homes to return to would have to wait for days until the threat of flooding subsided.

“We can't have any more deaths,” said Liu Xulong, a Mianyang official helping out at the city's Jiuzhou Stadium, where 4,000 people, mostly from devastated Beichuan County, remain.
Nearly a month after the quake, the official death toll crept up Saturday to 69,134 people, with 17,681 still missing.
Lakes formed by landslides are often unstable, creating the potential for massive flooding. A powerful quake in another part of Sichuan in 1786 dammed the Dadu River which collapsed 10 days later, killing over 100,000 people, according to historians.

Over the past two weeks, the government has mounted a hurried effort to drain Tangjiashan lake, bringing in soldiers on foot and flying in bulldozers by helicopter, to construct the 1,550-foot (475-meter) diversion channel.

“The Chinese government have responded to this in an impressive manner,” said David Petley, a geography professor at Britain's Durham University. “I don't believe that much more could have been done. Unfortunately the scale of the problem means that management is very challenging.”

Crucial to success will be whether government engineers can control the outflow from Tangjiashan, Petley said. A too-rapid flow of water would erode the drainage channel and surrounding hillsides, sucking even more water down the basin and potentially causing greater flooding.

In recent days, work teams shored up a railway bridge with additional steel beams downstream, while China National Petroleum Corp. reinforced a major oil pipeline, Xinhua said.
A loss of either could be a setback for recovery. The pipeline brings in 70 percent of Sichuan's oil, while the railway line, knocked out for two weeks, has been crucial to bringing in relief. Xinhua said Saturday that 85,000 sets of temporary houses have been brought in by rail.

The provincial government has estimated about 7,000 of the victims were children with no siblings. The National Population and Family Planning Commission will send a medical team to the quake zone to perform reverse sterilization operations on couples that want to have another child, Xinhua reported.

China's family planning policies restrict most couples to one child, although rules allow for another baby if their child is killed, severely injured or disabled.

Authorities said they had recorded 4,700 unclaimed children whose parents presumably died in the quake. But Civil Affairs Ministry official Zhang Shifeng said the final number of orphans was expected to be about 1,000 to 2,000, as children were gradually handed over to members of their extended families.

Zhang said parents from around China were showing huge interest in adopting quake orphans, with 10,000 families registering for adoption in one province alone. He indicated the ministry could give priority to parents who lost children in the quake.