Spatial characteristics of avalanche activity in an Alpine valley — a GIS approach

Abstract

Adataset of daily avalanche activity observed consistently for 14 years in the surroundings of Zuoz in the Engadine valley (eastern Swiss Alps) is analyzed. All medium-sized and larger avalanches had been mapped by the local snow and avalanche observer. They were digitized into a geographic information system (GIS) and linked to the daily snow and avalanche observations. Thus the avalanche activity and its spatial distribution could be analyzed and visualized. A classification for avalanche size and avalanche activity is proposed. In 52% of the potential starting zones an avalanche is released at least once in 14 years. The avalanche area decreases strongly with the frequency of avalanche occurrence. Preliminary analysis of the relation of daily avalanche activity to weather, snow and snow cover revealed a wide variety of contributory factors. Even for large amounts of new snow, snow-cover conditions prior to snowfall or temperature evolution might decide the extent of the avalanche activity. For six examples, the avalanche hazard (five degree European scale) is visualized by means of avalanche activity. The GIS approach will be followed to build a tool for local avalanche forecasting in Zuoz.