Item: Definition of hazard zones for dense snow avalanches
Title: Definition of hazard zones for dense snow avalanches
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Paolo Scotton1,*,Francesca Moro1, Stefano De Toni2, Daniele Dalla Valle1, Irene Vigni1 Department of Geosciences, University of Padova, Italy 2 Environmental Engineer, Italy
Abstract: The paper describes a procedure for the determination of snow avalanches Hazard Map developed after the observation, over some years, of the behaviour of some avalanches sites located near Trento (Italy). The dynamic of granular avalanches is simulated by means of a 1-D numerical model with variable width, based on the rheology of Savage and Hutter. The snow volume of the avalanche is defined estimating, statistically, the seasonal precipitation of snow, and estimating the surface of the accumulation catchment. Different values, associated to different return periods, are assigned to the above mentioned parameters. The physical parameters of the numerical and mathematical model are calibrated on the basis of the knowledge of extreme events, when available, to whom is associated, arbitrarily, a return time. The physical parameters vary along the flowing and the stopping zones depending on the return time and on the roughness and slope distribution along the flowing channel which can be modified on previous avalanche-events. It is hypothesized that, in the stopping area, the avalanche can follow different trajectories, defined on the basis of the local topography and on the assumption that the most likely trajectory can be modified by unpredictable causes of deviation. The criterion used for the definition of areas subjected to different hazard degree is the stopping distance. The hazard zone is divided into three areas associated to three different return periods.
Keywords: dense snow avalanche, granular rheology, hazard zoning
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