Item: The Systematic Snow Cover Diagnosis: A Process-Based Approach for Avalanche Danger Assessment
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Title: The Systematic Snow Cover Diagnosis: A Process-Based Approach for Avalanche Danger Assessment
Proceedings: International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - October 07-11, 2013
Authors:
- Georg Kronthaler [ Bavarian Avalanche Warning Service, Munich, Germany ]
- Christoph Mitterer [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Bernd Zenke [ Bavarian Avalanche Warning Service, Munich, Germany ]
- Michael Lehning [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
Date: 2013-10-07
Abstract: Recreationists and local avalanche warning services face often the problem of assessing the avalanche danger for a single slope or avalanche path. However, local avalanche danger and release probability for a single slope are both very difficult to predict. Since 1998 the Bavarian Avalanche Warning Service teaches a diagnostic approach for local avalanche authorities and recreationists to provide them a systematic approach for snowpack observations and avalanche danger assessment based on these observations. The key component of this tool is finding the most prominent weak layer, test the weak layer - slab combination with a fast test and interpret the result by considering the processes that lead to the situation observed. Since this approach has never been rigorously validated, we want to present results of a field campaign, which was conducted during the winter seasons 2008—2009 to 2010—2011. In order to corroborate the diagnostic approach, several observers performed snow cover observations that focused on determining the weak layer and testing the weak layer - slab combination with a fast test block. Based on this information the observer had to assess the release probability for the investigated slope. When compared to obvious signs of instability, i.e. avalanches, cracks or whumpfs, the release probability evaluation was in very good agreement. Slopes with a high release probability had mostly a combination of a prominent weak layer, a cohesive slab, sudden fractures and low test scores. In addition to predicting the release probability of the slope tested, the observers had to estimate the danger for neighbouring slopes, which were subsequently evaluated. The transferability of the danger assessment was depended on the danger level and therefore the type of weak layer. Persistent weak layers causing situations with high release probability could be transferred with very good agreement, while situations with lower release probability were more often not found in the neighbouring slopes. With other words at low release probability the variability of the prominent weak layer was higher than for situations with high release probability. The presented approach gives the possibility to include snow cover properties into the evaluation of avalanche danger for a specific slope and provides robust results.
Language of Article: English
Presenters: Unknown
Keywords: slope stability, snow cover test, weak layer
Page Number(s): 199-202
Subjects: snow cover slope stability weak layers
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Digital Abstract Not Available
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