Les travaux paravalanches de Saint Colomban des Villards

Avalanche protection for Saint Colomban des Villards in the French Alps

Ingénieur en Chef des Eaux et Forêts

Abstract

The avalanche protection scheme for the Saint Colomban des Villards district, which is to ensure the safety of several villages, is unique in France by the complete, efficient protection it is designed to provide. Owing to its high cost and long-term implementation schedule, the project was taken over by the French Government, which ensured that the Forestry Authorities would have the time and facilities they required for preparing a rational work schedule and putting it into effect over a period of 20 years. As the first and most urgent requirement, several "passive" protection works were installed (diversion dykes at the outlets from the main avalanche corridors). An access road was then built to areas it was considered could be stabilized at reasonable cost. Next, various conventional types of snow barrier were installed, ranging from simple banks to racks capable of withstanding the heaviest snow loads. Finally, trees were planted between, in and around the protection works. Despite some failures caused by a series of exceptionally snowy winters, retimbering seems to have been successful on the whole ; the new trees at various sites should be capable of taking over from the anti-avalanche works within the next 10 to 25 years. Even taking a very conservative view of the results so far, it seems reasonable to claim that the anti-avalanche works in the Saint Colomban des Villards district have been effective during several very snowy winters, in which unprotected areas suffered disastrous avalanches. The project, which also includes the smaller Cellier district, is the first of its kind to have been put into effect in the French Alps ; in addition, it has provided the Forestry Authorities with excellent scope for experimentation. The anti-avalanche works attract a good many visitors to the area.