Trapped chemicals add to China's lake fears
DUJIANGYAN, China (Reuters) - Five thousand tonnes ofdangerous chemicals is adding to the mix of threats downstreamfrom one of China's "quake lakes" in danger of bursting theirbanks, a newspaper said on Thursday.
About 5,000 tonnes of chemicals, including sulphuric andhydrochloric acid, were trapped downstream from the Tangjiashanlake and had to be moved to safe ground, the Beijing News said,citing local environmental authorities.
China has evacuated more than 150,000 people living belowthe swollen Tangjiashan lake formed by this month's devastatingearthquake amid fears it could burst and trigger massiveflooding.
The chemicals, adding pollution to the threat of flooding,were stranded in different work sites downstream, the newspapersaid.
But radioactive materials had been largely recovered, thenewspaper cited Ma Ning, director of the Southwest ChinaEnvironmental Protection Supervision Centre, as saying. Thedisaster area is home to China's chief nuclear weapons researchlab in Mianyang, as well as several secretive atomic sites, butno nuclear power stations.
The Tangjiashan lake was created when landslides blockedthe Jianjiang river above the town and county of Beichuan inmountainous Sichuan province, near the epicentre of China'smost destructive earthquake in decades.
SUDDEN BREAK
Alexander Densmore, a seismologist at Durham University inBritain, said any break in a quake lake would likely be sudden.
"It's a very real problem," said Densmore by telephone."These landslide dams pose a really significant risk in thesemountain regions, and in these narrow valleys it doesn't takemuch material to create a complete blockage."
Once a breach occurred, there could be an acceleratingprocess leading to a sudden rush of water downstream.
"Once that process starts, it's virtually impossible to doanything to decrease the water... When they fail, they tend tofail catastrophically," he said of the quake dams.
Given the topography of Sichuan, with the western mountaincountry giving way to plains around Mianyang, a major rush ofwater could spill downstream and possibly affect lower-lyingareas of cities such as Mianyang, he said.
The region along the faultline is densely packed with dams,raising concerns that if either the quake lakes or the weakeneddams burst, the rush of water could cause others to fail.
The official death toll from the 7.9 magnitude quake isalready more than 68,000 and is certain to rise further, withnearly 20,000 listed as missing. Aftershocks on Tuesday toppled420,000 houses, many already uninhabitable.
A massive relief effort, which involves providing food,tents and clothing for millions and the reconstruction ofhousing and infrastructure, is expected to take up to threeyears.
Thousands of injured have been transferred to otherprovinces and the capital for treatment to ease the pressure onlocal hospitals.
Song Liangwei, 9, had always dreamed of visiting Beijing,but not as a quake victim.
"I wanted to go to Tiananmen Square, to climb the GreatWall, and to watch the Olympic Games," he said.
(Writing by Nick Macfie; Additional reporting by LindsayBeck, Chris Buckley and Phyllis Xu in Beijing; Editing by BillTarrant)