Item: Avalanche modeling in france - theory and applications
Title: Avalanche modeling in france - theory and applications
Proceedings: Proceedings of the 1996 International Snow Science Workshop, Banff, Canada
Authors: Mohamed Naaim, Gerard Brugnot and Jean Claude Charry, Cemagref, Division Nivologie, B.P.76, F-38402, Saint Martin d'Heres, France
Abstract: First, this paper succinctly describes our numerical powder snow avalanche model. Then, an application of this model is presented in the frame of an avalanche zoning. This application is an example of a practical use of the numerical model in avalanche risk engineering. For each study the model was used to simulate different avalanche scenarios. It allows to give a coherence between input data (production conditions) and the effects of the avalanche. The use of the model can be made according to the following process: First it begins with searching in the archives for the most important powder snow avalanche having taken place on the site. This search concerns the conditions of production as well as the effects of the avalanche in its flowing and run-out zones. For this purpose, different indicators can be used. All caused damages "indicate" that the dynamic pressure developed by the avalanche was superior to the threshold stress of the damaged objects (tree, pylon, etc.). Effects are mapped in terms of pressure fields. Secondly we use the numerical model to simulate an avalanche scenarios whose entry conditions take into account all the available observations concerning the production factors (meteorology, snow, starting zone etc.). It is important to note here that such type of data is very often sketchy for several technical reasons ( access to starting zone ... ). Several numerical simulations allow to specify and complete the model input conditions. The purpose is to define a "reference avalanche" which produces effects similar to the observed one (pressure field, velocities, height etc.). Last we define the "observed-extreme-avalanche" and simulate it. The model gives access to a large spectra of scenarios by increasing or reducing production conditions or by modifying the topography of the flowing or run-out zones. Therefore, we can build a database of avalanches that can be used in defining the protection for the desired site.
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Keywords: model, risk, avalanche
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