Item: 2d modelling of icelandic snow avalanches for hazard zoning
Title: 2d modelling of icelandic snow avalanches for hazard zoning
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Eiríkur Gíslason1 1 Icelandic Meteorological Office, Ísafjörður, Iceland
Abstract: The methodology for snow avalanche hazard zoning in Iceland is based on a statistical run-out analysis of a data-set of historical avalanches. The method makes use of the one-dimensional PCM snow avalanche model to define a quantitative measure of run-out which is termed run-out index. The data-set is being revised and expanded to include recent events. The samosAT twodimensional model was used to simulate some of the avalanches in the data-set. The run-out index concept has been expanded to two dimensions and a new statistical run-out distribution was derived based on the two-dimensional indices. Simulation results verify that the two-dimensional model is able to take into account the effect of various geometrical features of avalanche paths that cannot be represented by one-dimensional avalanche models. Thus, the effect of lateral geometry to form tongues of long run-out below gullies in the mountainside is taken into account. The 2D model results show a distinct difference in relative run-out lengths compared with more conventional one-dimensional avalanche along longitudinal profiles. Geometrical features of the avalanche path can thus be used to explain a part of the difference in return periods between paths. This leads to more consistent return period estimates. The two-dimensional run-out index concept and the revised run-out distribution have the potential to make the hazard zoning procedure more objective and provide quantitative arguments for the shape of tongues in hazard zones. This reduces the reliance on subjective judgment of the avalanche expert in the hazard zoning process compared to the previous methodology.
Keywords: avalanche modelling, two-dimensional run-out index, hazard zoning
Digital Abstract Not Available