Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 16, 1953-1965, 2016
https://doi.org/10.5194/nhess-16-1953-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
17 Aug 2016
Linking snow depth to avalanche release area size: measurements from the Vallée de la Sionne field site
Jochen Veitinger and Betty Sovilla WSL Institute for Snow and Avalanche Research SLF, Unit Snow Avalanches and Prevention, Davos, Switzerland
Abstract. 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. Terrain analysis plays an important role in assessing the potential size of avalanche releases areas and is commonly based on digital terrain models (DTMs) of a snow-free summer terrain. However, a snow-covered winter terrain can significantly differ from its underlying, snow-free terrain. This may lead to different, and/or potentially larger release areas. 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 field site. 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 of snow depth around those critical features where snow can accumulate over a long period before becoming susceptible to 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 routes or ski resorts.

Citation: Veitinger, J. and Sovilla, B.: Linking snow depth to avalanche release area size: measurements from the Vallée de la Sionne field site, Nat. Hazards Earth Syst. Sci., 16, 1953-1965, https://doi.org/10.5194/nhess-16-1953-2016, 2016.
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Short summary
One of the major challenges in snow avalanche hazard assessment is the correct estimation of release area size, which is of crucial importance in the evaluation of the potential danger that avalanches pose to roads, railways or infrastructure. In this study we show that snow depth can serve as a useful variable with regard to potential release area definition for varying snow cover scenarios. This may ultimately improve avalanche hazard assessment of transport routes or ski resorts.
One of the major challenges in snow avalanche hazard assessment is the correct estimation of...
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