The snow avalanches risk in the upper san isidro valley (Asturian central massif): The vulnerability of the as-253 road

Abstract

The snow avalanches risk in the Upper San Isidro Valley is analysed, in particular, the factors that contribute to its triggering, the identification of probable snow avalanches areas and the vulnerability of the AS-253 road that climbs to the Port of San Isidro, in order to mitigate the impact and damage caused by snow avalanches on a recurring basis. The methodology used combines field observations, the photointerpretation of aerial images, analysis of hemerographic sources and surveys of the inhabitant of the council of Aller. Additionally historical climatic data, especially of snowstorms and the behaviour of recent nivosity through the hourly monitoring of the last snowfalls was studied. As a result, the historical evolution of snowstorms is established and correlation with snow avalanches is specified. Effectively, 63 snow avalanche areas were identified, 24 of which affect the road, presenting a 14% of its length high vulnerability. In addition, 10 reaches of road show a high risk of snow avalanches, lacking any protection measure, so it is necessary to immediately carry out preventive actions, among others, the installation of several rows of snow nets.