By Richard Gravelle
Engineers have begun an operation to drain a meltwater lake that has formed beneath a glacier in the Mont Blanc massif.
The lake, which lies underneath the Tete-Rousse glacier, threatens to flood the Saint Gervais valley with approximately 65,000 m3 of meltwater. The valley is home to around 3,000 people, and contains the world-famous ski resort of Chamonix, so the effects of the lake draining could be catastrophic. A previous flood in 1892 from another subglacial lake killed 175 people.
It is believed that warmer summer temperatures may have caused an increase in meltwater production which caused the lake to form, but that a period of cold temperatures may have closed a number of natural drainage routes, and preventing the water from draining away.
The engineers will have to drill a 40-50 m deep borehole in the glacier ice before they reach the lake water level. The water can then be pumped away, making the valley safe once more.
It is thought that the drainage operation will cost around €2 (approximately £1,600,000). However, if the project is successful, then the cost saved in human life and livelihoods will be far greater.