26 May 2008
China Daily is today reporting that real progress is being made with the lake above Beichuan, which is now known as Tangjiashan Lake:
Amid low visibility, a Russian helicopter successfully delivered a large bulldozer and other eight sets of big machineries near the swelling Tangjiashan lake, in order to dig a diverting channel to prevent a flood, said Minister of Water Resources Chen Lei. “I feel relieved this morning as we have reached the area,” said Chen, who is in charge of dealing with the emergency situation of dozens of quake lakes in Sichuan. Quake lakes were formed after landslides blocked rivers.“All these mean we can officially start to deal with swelling lakes now,” said Chen, adding it first time he spoke to the media, as he was not in the mood the previous days to do failures to deal with the possible flooding situation. Other helicopters managed to airdrop materials for the operation by 7:49 am Monday at the top of the quake lake at Tangjiashan in Beichuan County. It was formed by landslides that blocked a local river known as Jianhe after the May 12 earthquake. While military forces are preparing to dynamite the swelling Tangjiashan quake lake, rescue headquarters have urged the expert team to quickly give “risk evaluation” reports on bursting of the barrier. Chen asked the provincial and Mianyang municipal governments to draw “three red lines” on the map until Tuesday noon, with each representing which area will be affected if the barrier bursts by one third, half or to nothing.
This sounds much more promising. The best way to deal with this issue is a combination of a channel constructed using heavy equipment, backed up with an assessment of the areas likely to be inundated by a flood. Blasting the dam should be avoided if at all possible – it is a real last gasp approach. However, great care will be needed in the construction of the channel, in particular in preventing rapid erosion of the channel bed and thus a rapid collapse event.
This is progress for sure but they are not yet out of the woods. The lake now has a volume of >128 million cubic metres of water.