Threat recedes as quake lake shrinks

MIANYANG: The water level in the Tangjiashan Lake in Sichuan Province could drop below the danger line, as lake water flows into the low-lying areas.

The lake’s water level had dropped to 725.8 metres, down about 18 metres in the past 24 hours. Its water volume had shrunk by 90 million cubic metres to 160 million cubic metres, said officials at the emergency rescue headquarters. Yet, water conservancy experts warned the lake and its dam remained in danger until the water level dropped below 720 metres. The 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.

Precautions taken

More than 2,50,000 people in low-lying areas in Mianyang have been relocated under a plan based on the assumption that one-third of the lake volume breached the dam.

In Jiangyou, a city sandwiched between Beichuan and Mianyang, trees, barrels, TVs, fridges and the occasional bodies of quake victims were spotted 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 landslips and dam bursts, said Commander-In-Chief Jiang Jufeng.

Hydrological workers had already observed cracks in the dam, and helicopters were arranged to evacuate emergency workers. More than 200 armed police officers worked round the clock for four days to drain the lake. Once overflowed, it could threaten some 1 million residents living on the lower reaches.

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

Tangjiashan Lake, formed after quake-triggered landslips from the Tangjiashan Mountain, blocked the Tongkou River running through Beichuan County. — Xinhua