Item: The Role of Slope Angle, Ground Roughness and Stauchwall Strength in the Formation of Glide-Snow Avalanches in Forest Gaps
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Title: The Role of Slope Angle, Ground Roughness and Stauchwall Strength in the Formation of Glide-Snow Avalanches in Forest Gaps
Proceedings: International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - October 07-11, 2013
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 ]
- P. Bartelt [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
Date: 2013-10-07
Abstract: Mountain forests are a cost-efficient measure to prevent the release of glide-snow avalanches. However, avalanches still release in forest gaps. Well-tested silvicultural guidelines have been formulated to define the maximum gap dimensions. The guidelines are based on empirical observations and are valuable tools for forest managers. In this paper, we develop a physical model to describe the formation of glide-snow avalanches in forest clearings. Our goal is to place forest management guidelines on a better physical foundation which allows a more detailed examination of possible mitigation measures, including the role of dead-wood, surface modifications and underbrush. We model the snow cover as a two-dimensional visco-elastic continuum with a strain-rate dependent failure criterion. Avalanche release is hindered by basal friction at the snow-soil interface as well as the strength of the stauchwall located at the lower end of the release slab. The stauchwall resists the displacement of the gliding slab when melt-water reduces the basal friction. The stabilizing effects of trees are taken into account as they support the stauchwall. Our preliminary results reveal that for slope angles lower than 35 ground roughness prevents glide-snow avalanches from release; however, small trees and underbrush are often insufficient to prevent release in steep terrain. Our findings are consistent with the Swiss forest management guidelines for avalanche prevention. Not only the release area itself but also the stauchwall zone is crucial for glide-snow avalanche release. We discuss how the snow cover at the lower end of forest gaps could be supported through silvicultural management.
Object ID: ISSW13_paper_P2-57.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: forest avalanches, glide-snow avalanche, release, snow cover
Page Number(s): 760-765
Subjects: glide avalanche forest avalanche avalanche release
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