The soldiers have used mechanical diggers to carve out a 200-metre channel along the Tangjiashan lake, one of 34 bodies of water formed by landslides after the quake. Troops are also preparing explosive charges to "dynamite the barrier" of the lake, state media said.
State television said the lake, now holding about 128 million cubic metres of water, should be safe for the next 10 days, the time it is expected to take the army to clear debris. But experts have warned that it is difficult to predict when the landslide dams will burst.
Heavy rain is forecast. Almost three quarters of the 60 centimetres of rain that falls in Sichuan in an average year comes in the summer, the Guardian reported.
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Source: NASA
This series of images shows the formation of one "quake lake", Yansai Lake, in a mountain valley in Beichuan county. The county is one of the most severely affected quake regions.