Alert remains as main quake lake "Tangjiashan lake" keeps swelling

Source: Xinhua | 06-09-2008 16:50

Special Report:   Strong quake jolts SW China

MIANYANG, Sichuan, June 9 (Xinhua) -- China remained on alert Monday as the water level of the Tangjiashan quake-formed lake in the southwestern Sichuan Province continued to rise after two days of drainage.

The water level in the lake reached 742.58 meters above sea level as of 8 a.m. Monday, a rise of 0.92 meters in 24 hours, and 2.21 meters higher than the manmade sluice that began operation on Saturday morning.

Engineering soldiers fire a missile to blast boulders in a  man-made sluice channel in Tangjiashan, quake-hit southwest  China's Sichuan Province, June 8, 2008. A total of 4 missiles were fired on Sunday to clear boulders in the sluice channel,  which speeded up the drainage of the dangerous Tangjiashan  quake lake that began on Saturday morning.(Xinhua Photo)

As of 8 a.m. Monday, the lake's volume was 245.7 million cubic meters and the daily average influx was 115 cubic meters per second.

The sluice appeared to be operating smoothly, but even after military engineers fired short-range missiles more than 10 times on Monday to blast boulders in the channel, the drainage was accelerated to about 50 cubic meters per second, still far slower than the influx.

Every 20 minutes, a helicopter would land on the lake's dam, carrying soldiers and detonators to blast away the rocks that posed a bottleneck at the end of the spillway.

Three tons of dynamite were exhausted on Sunday and Monday to blast the boulders -- and to widen the channel to 10 meters from less than five reported on Saturday.

At the bottom of the dam, more than 20 bulldozers and at least 100 armed police officers have been digging for three days a new spillway, hoping to further accelerate the drainage.

Another aftershock jolted the lake at 11:04 a.m. Monday when rocks rolled down the surrounding mountains into the lake, posing higher pressure on the dam.

By then, experts were still monitoring the potential impact of Sunday's rainfall and massive landslides triggered by a 4.8-magnitude aftershock.

"Yesterday's rain and aftershock disrupted our work, but we are working against time to make up for it," said Xu Qiangguo, an officer with the hydropower force of the armed police.

Soldiers were toiling for hours on end under Monday's scorching sun, eating instant noodles and biscuits as their makeshift meals.

Experts were also testing two drilling machines, which were airlifted to the dam at 1:30 p.m. and would hopefully find out the geological structure in the area.

The Tangjiashan "quake lake", formed after quake-triggered landslides from Tangjiashan Mountain, blocked the Tongkou River running through Beichuan County, one of the worst-hit areas in the May 12 quake.

The largest of more than 30 quake lakes in Sichuan after the quake, Tangjiashan threatens some 1 million residents living in the lower reaches of the river once it overflows.

More than 250,000 people in low-lying areas in Mianyang City have been relocated under a plan based on the assumption that one-third of the lake volume breached the dam.

 

Editor:Du Xiaodan