French Glacier Flood Threat

The reservoir of water, roughly the volume of 20 Olympic-size pools, was discovered by researchers at the French National Center for Scientific Research (CNRS) during routine checks of the glacier last month. Experts say that the pocket probably formed as unusually cold temperatures froze the water's escape routes within the glacier. Normally, glacier water drains naturally, trickling away through the channels.

Workers toiled at an altitude of 3,200 metres (10,500 feet), pouring hot water on the ice to make a hole through which they will push a pump and start tapping off the water that has accumulated below one of the glaciers. Some 65,000 cubic metres (2.3 million cubic feet) of water have gathered in a cavity which is under immense pressure from the ice above. They estimated that if the water pocket explodes it would submerge the valley within 15 minutes, endangering the lives of more than 3,000 people in the area. Residents have been informed about the measures and briefed on an evacuation plan.

The pump, which can pass 50 cubic metres of water an hour, aims ‘to let out an initial jet of water... to avoid the pressure-cooker effect', Jean-Marc Peillex (mayor of Saint-Gervais-les-Bains) said. ‘These first cubic metres of water are the most important', said the head of the operation, Nicolas Karr of the mountain conservation service. ‘They will allow us to secure the site by lowering the pressure.'

The pump is targeting the main cavity containing 25,000 cubic metres and could also drain other surrounding pockets. Draining away the contents entirely will take weeks, the team said.
Workers hope that by pumping at this spot they will be able also to collect water trapped in other cavities and drain it away, said glaciologist Christian Vincent of CNRS.

Three more powerful pumps will be flown by helicopter to help with the job, due to last until October. A team of 15 workers, sleeping on the mountain and being looked after by mountain guides, will work 24 hours a day. ‘A month from now it will be much more difficult. There's a risk it will start snowing and we would have to deal with an avalanche', said one guide, Alban Faure.

Local authorities are fearing a repeat of the catastrophic flood in July 1892, when an estimated 17.6 million gallons of water mixed with mud, rocks and trees killed at least 175 people in the valley.

Source: AFP News, Circle of Blue