Monday, June 9, 2008

Chinese quake lake still rising

An engineering soldier prepares to fire a missile to blast boulders in a man-made sluice channel in Tangjiashan lake
Soldiers used anti-tank weapons to blast rocks and mud from the area

The water level in an earthquake-formed lake in China is still rising, despite the creation of a drainage channel.

By early Monday, the water level was more than 6 feet (2m) higher than the man-made channel created to ease the problem, Xinhua news agency said.

Soldiers are using anti-tank weapons to blast away rocks and mud preventing the water from getting to the channel.

Experts warn that the lake could burst at any time, flooding the homes of more than one million people.

About 250,000 people have already been evacuated from the area since the devastating 12 May earthquake, which caused Tangjiashan quake lake to form.

Latest government figures put the quake death toll at 69,136 with another 17,686 people missing.

Tangjiashan lake is the largest of more than 30 quake lakes created by last month's 7.9 magnitude tremor.

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Chinese soldiers' efforts to get the lake to drain faster

Firing shells

Managing to stem the rise of water levels in Tangjiashan lake has become a priority for a government, as it tries to prevent further disaster.

Army official Fan Xiao Guang told the Associated Press news agency that troops were firing shells at close range, to "make sure the water gets through the channel".

Soldiers use explosives to widen a channel to release water at the Shibangou quake-formed lake in earthquake-hit Qingchuan
More than 30 lakes were created when the earthquake hit
According to state media, the soldiers have managed to make the run-off channel wider and deeper, helping to reduce the water level in the lake, and are now working on a second drainage channel.

But there is a long way to go, and despite their efforts the amount of water in the lake is still increasing.

Zhang Ting, head of the Sichuan provincial hydro-meteorological bureau, told state media "the drainage plus natural leakage from the lake is about 25 cubic metres per second, while the inflow is 4.6 times greater".

"Increasing the outflow of water is critical for the dam's safety," Mr Zhang told the China Daily.

Map

Mapping the quake zone
In pictures: Draining the lake
"If the water flows too slowly, the inflow will increase the pressure on the dam. But again, too voluminous an outflow can erode the diversion channel and cause the dam to collapse."

Rainfall and further landslides caused by a 4.8 magnitude aftershock on Sunday afternoon have made the situation harder still, increasing pressure on the lake's banks, according to Xinhua news agency.

A further aftershock was felt at 11:00 am (0300 GMT) on Monday, Xinhua said.

1 comments:

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