One of the major challenges in avalanche hazard assessment is the correct estimation of avalanche release area size which is of crucial importance to evaluate the potential danger that avalanches pose to roads, railways or infrastructure. The assessment of potential release area size is nowadays mainly based on terrain analysis; however, it is assumed that with increasing snow accumulation and the attenuation of terrain irregularities larger release areas may form. To investigate this hypothesis, the relation between avalanche release area size, snow depth and surface roughness was investigated using avalanche observations of artificially triggered slab avalanches over a period of 15 years in a high-alpine fieldsite. High resolution, continuous snow depth measurements at times of avalanche release showed a decrease of mean surface roughness with increasing release area size both for the bed surface and the snow surface before avalanche release. Further, surface roughness patterns in snow covered winter terrain appeared to be well suited to demarcate release areas, suggesting an increase of potential release area size with greater snow depth. In this context, snow depth around terrain features that serve as potential delineation borders, such as ridges or trenches, appeared to be particularly relevant for release area size. Furthermore, snow depth measured at a nearby weather station was to a considerable extent related to potential release area size, as it was often representative for snow depth around those critical features where snow can accumulate over a long period before becoming susceptible for avalanche release. Snow depth – due to its link to surface roughness – could therefore serve as a highly useful variable with regard to potential release area definition for varying snow cover scenarios, as for example, the avalanche hazard assessment for transport ways or ski resorts.
Veitinger, J., & Sovilla, B. (2016). Linking snow depth to avalanche release area size: Measurements from the Vallée de la Sionne field site. Natural Hazards and Earth System Sciences, 16(8), 1953–1965. https://doi.org/10.5194/nhess-16-1953-2016