Tangjiashan Quake Lake Expected to Shrink

Picture taken at 9 a.m. on June 10, 2008 from a military helicopter shows the drainage of the Tangjiashan quake lake in southewest China's Sichuan Province. Drainage of the quake lake through a manmade spillway speeded up to 1,760 cubic meters per second at 9:30 am on Tuesday, whereas water flow in the lower reaches of the lake, in Beichuan County, reached 2,240 cubic meters per second.

The water level in the Tangjiashan quake-formed lake in southwest China's Sichuan Province will likely drop below the danger line Tuesday, as muddy lake water flows into the low-lying areas.

Drainage of the quake lake through a man-made spillway speeded up to 6,420 cubic meters per second at 11:30 a.m., before it slowed to a steady 3,888 cubic meters per second at 2:30 p.m..

As of 3 p.m., the lake's water level had dropped to 725.8 meters, down about 18 meters in the past 24 hours. Its water volume had shrunk by 90 million cubic meters to 160 million cubic meters as of 1 p.m., the Tangjiashan Lake emergency rescue headquarters said.

Yet, water conservancy experts warned the lake and its dam remained in danger until the water level dropped below 720 meters.

Due to the torrential outflow, the water level was decreasing from 740.37 meters above the sea level when the spillway became operational on Saturday morning.

The brownish lake water burst the dams of four smaller quake lakes on the lower reaches of Tangjiashan and flowed into the low-lying Beichuan County that had been flattened in the 8.0-magnitude quake on May 12.

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

Xinhua reporters in Jiangyou, a city sandwiched between Beichuan and Mianyang, saw trees, barrels, TVs, fridges and the occasional dead bodies of quake victims in the roaring flood water.

Faster drainage of the Tangjiashan Lake had eased the peril on the lower reaches, but the emergency headquarters was still on alert for further landslides and dam bursts, said Commander-In-Chief Jiang Jufeng.

Hydrological workers had already observed cracks in the dam, and helicopters were arranged to evacuate all the emergency workers, mostly soldiers with the People's Liberation Army (PLA) and the armed police.

More than 200 armed police officers worked round the clock for four days to drain the lake. Once overflowed, it could threatens some 1 million residents living on the lower reaches.

A manmade spillway started to drain from the lake on Saturday morning and military engineers fired short-range missiles several times on Sunday and Monday to blast boulders in the channel and speed up the outflow.

As a result of two massive blasts on Monday evening which broke through the "bottleneck" in the spillway, the water outflow speeded up drastically on Tuesday compared with 80 cubic meters on Monday night.

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