Item: Stopping Behavior of Snow Avalanches in Forests
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Title: Stopping Behavior of Snow Avalanches in Forests
Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska
Authors:
- T. Feistl [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ Technical University Munich (TUM), Munich, Germany ]
- P. Bebi [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Y. B ̈uhler [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- M. Christen [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- M. Teich [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ Swiss Federal Institute of Technology (ETH), Zurich, Switzerland ]
- P. Bartelt [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
Date: 2012
Abstract: A longstanding problem in avalanche science is to understand how forests stop small and medium sized avalanches. Avalanche dynamics models have traditionally been employed to calculate extreme avalanche runout and have assigned a minor role to forests in dissipating flow energy. In this paper we quantify the important effect of forests in stopping small avalanche events, crucial for road and ski-run safety. We performed field studies of several avalanches where trees affected the runout. We gathered information concerning the starting location, deposition heights, runout distance and forest structure. These studies were made during the 2011/12 winter where many gliding snow avalanches released in forested areas in Switzerland and Germany. Using the field observations as a guide, we hypothesized that mass detrainment due to tree-avalanche interaction led to a significant deceleration of the avalanches. This effect is important for physical based avalanche dynamics models which reveal that avalanche mobility is strongly linked to mass entrainment/detrainment. We tested this hypothesis with a numerical experiment and simulated the documented avalanche events using a velocity dependent detrainment model to reconstruct the braking effect of forests. For the numerical investigations we used high spatial resolution digital terrain models. The results highlight how forests influence mass and energy fluxes at the front and sides of avalanches. Of particular importance is the distribution of velocity across the flow width of the avalanche, as flow mass can be easily stopped at the flow boundaries.
Object ID: issw-2012-420-426.pdf
Language of Article: English
Presenter(s): unknown
Keywords: forests, avalanche science, runout, dynamics
Page Number(s): 420-426
Subjects: avalanche danger forest avalanche snow avalanche dynamics
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