A terrible tragedy, with yet more complications for the water system.
It's interesting to compare this with last week's reports that water quality was not affected by the earthquake.
Peter Huston
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http://www.iht.com/articles/reuters/2008/05/29/asia/OUKWD-UK-QUAKE1.php
Chemicals add to China's quake lake fears
By Tyra Dempster Reuters
Published: May 29, 2008
DUJIANGYAN, China: Five thousand tonnes of dangerous chemicals and heavy rain are adding to the mix of threats from one of China's "quake lakes" in danger of bursting their banks, a newspaper said on Thursday.
Illustrating the sense of urgency, the Finance Ministry said it was funnelling an extra 1 billion yuan (73 million pounds) into relief work on an estimated 35 quake lakes in addition to 400 million yuan already allotted to work on smaller, damaged dams.
About 5,000 tonnes of chemicals, including sulphuric and hydrochloric acid, were trapped downstream from the Tangjiashan lake 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 below the swollen Tangjiashan lake, formed by the devastating May 12 earthquake, amid fears it could burst and trigger massive flooding.
The official death toll from the 7.9 magnitude quake is already more than 68,500 and is certain to rise further, with nearly 20,000 listed as missing. Aftershocks on Tuesday toppled 420,000 houses, many already uninhabitable.
The chemicals, adding pollution to the threat of flooding, were stranded in different work sites downstream from the lake, the newspaper said.
The Tangjiashan lake was created when landslides blocked the Jianjiang river above the town and county of Beichuan in mountainous Sichuan province, near the quake epicentre.
It has been raining at the site from early Thursday, hampering efforts by more than 600 soldiers to open a giant sluice to discharge floodwaters, Xinhua news agency said. Helicopters shipping in equipment were unable to take off.
Some 1,000 People's Liberation Army soldiers were making their way by foot to the lake, carrying more than 10 tonnes of diesel for bulldozers already there.
SUDDEN BREAK
Alexander Densmore, a seismologist at Durham University in Britain, said any break in a quake lake would likely be sudden.
"These landslide dams pose a really significant risk in these mountain regions, and in these narrow valleys it doesn't take much material to create a complete blockage," he said by phone.
Once a breach occurred, there could be an accelerating process leading to a sudden rush of water downstream.
"Once that process starts, it's virtually impossible to do anything to decrease the water... When they fail, they tend to fail catastrophically," he said of the quake dams.
Given the topography of Sichuan, with the western mountain country giving way to plains around Mianyang, a major rush of water could spill downstream and possibly affect lower-lying areas 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 weakened dams burst, the rush of water could cause others to fail.
A massive relief effort, which involves providing food, tents and clothing for millions and the reconstruction of housing and infrastructure, including the many destroyed schools, is expected to take up to three years.
Donations from home and abroad had reached 37.3 billion yuan by Thursday, up 2.5 billion yuan from the previous day, the Information Office of the State Council said.
China did not confirm reports on Wednesday that it had requested aid from Japan.
"If the Japanese self-defence forces are ready to provide assistance, the specifics will be discussed at the defence departments of the two countries," Foreign Ministry spokesman Qin Gang told a news conference, adding that South Korean President Lee Myung-bak would visit Sichuan on Friday.
Thousands of injured have been transferred to other provinces and the capital for treatment. 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 Great Wall, and to watch the Olympic Games," he said.
(Writing by Nick Macfie; Additional reporting by Lindsay Beck, Chris Buckley, Guo Shipeng and Phyllis Xu in Beijing; Editing by Sanjeev Miglani)
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