Tourism
Thousands of cubic metres of water have been drained from a glacier in the Mont Blanc massif in order to prevent a catastrophe. Swift action and increased monitoring will be needed to deal with the impacts of climate change in mountain regions.
The beautiful French village of Saint-Gervais-les-Bains is a popular ski resort which, like many Alpine communities, relies heavily on tourism. However, a startling discovery was made in the summer of 2010.
During a routine inspection of the nearby Tête Rousse glacier, some 65 000 cubic metres of liquid water was detected, a significant amount of which had collected in a single cavity. If there had been a rupture in the glacier, in only 15 minutes this immense body of water could have flooded the entire valley, home to 3 000 people.
Concerns about this trapped body of water were not based on a hypothetical disaster scenario – in 1892, water from a similar glacial cavity flooded the same valley, killing an estimated 175 people.
“In July, we had a similar situation as was faced in 1892, with a comparable volume [of water]. However, with development in the valley since the last century, the number of threatened inhabitants has increased significantly,” says Nicolas Karr from France's National Forests Office.
Alpine engineering
It became clear that the glacial cavity needed to be drained. This operation was extremely delicate, especially because of the constant danger of avalanches. “The drilling and artificial drainage of an intra-glacial cavity had never before been achieved,” says Karr.
“We therefore had to think up the technical means of attempting this operation. We also had to finish [work] on-site by mid-October, as after this point there would be too much snow.” Another complicating factor was that access to the operation on the glacier, situated at 3 200 metres above sea level, was only possible by helicopter.
On this inhospitable terrain, engineers drilled 50 metres through the ice to reach the water cavity. A 22-centimetre diameter hole was made so that water contained in the pocket could be pumped to the surface, with hot water used to pierce the ice.
Submerged pumps were then sent in. At the same time, scientists had to be careful not to disrupt the delicate Alpine ecosystem or inadvertently trigger the kind of natural disaster they were trying to prevent.
Three months after the problem was discovered, the operation has been a success. “48 000 cubic metres of water have been pumped out. As a result, the pressure of the water on the ice cap has dropped from 7-8 bars to less than a bar,” explains Mr Karr.
Trouble for tourism
Careful inspection and cutting-edge engineering applied quickly, ensured that the Saint-Gervais valley will not experience a disaster like the devastating flood of 1892 – at least for the foreseeable future. But the incident underlines the precarious existence of communities such as Saint-Gervais-les-Bains, which rely on the mountains for their livelihoods.
“The creation of this pocket cavity was caused by the diminishing thickness of the snow on the glacier, the result of global warming,” explains Mr Karr. “The role played by this bed of snow in thermally insulating the ice was therefore reduced. The glacier cooled in such a way that the front of the glacier ‘glued’ itself to the rock, unable to let water exit in the usual manner.”
This is a paradoxical effect of climate change, where rising temperatures can have a ‘freezing’ effect. The ‘tongue’ of the glacier – no longer insulated by a blanket of snow – froze, allowing an internal cavity to fill up with trapped water that was unable to drain away.
The Tête Rousse project forcefully brought home how climate change can have a catastrophic impact on communities living beneath glaciers, and underlined how the Alpine region, hugely popular with tourists, is being seriously affected by climate change.
Aside from the immediate damage to human lives and the environment that such a flood would have caused, the changes also threaten livelihoods that rely on the mountains. During the pumping operation on the glacier, for example, local authorities had to close the final section of the Mont Blanc tramway which passes close to the glacier.
Short and long-term action to adapt to climate change has an impact on visitors to the region, but the impact of doing nothing would be much worse.