Objective Comparison of Two Numerical Avalanche Dynamics Models.

International Snow Science Workshop

2012

6 S.

SonderdruckMonographie

176120

Numerical avalanche dynamics models are nowadays used by engineers all around the world as an integral part in risk assessment studies. Especially in areas like the European Alps with limited space suitable for settlements the demand for high quality hazard zoning is present and models have become increasingly important. Two of the leading software tools are SamosAT (AT) and RAMMS (CH). The underlying flow models deviate in their numerical implementation and in their physical assumptions. Both software tools provide results on the time and spatial evolution of avalanche flow dynamical parameters such as flow depth and velocity. The complexity and huge amount of result data makes an objective comparison of a high number of simulations challenging and difficult to interpret by decision makers. In this paper we objectively compare the two software tools, using a new approach called AIMEC (Automated Indicator based Model Evaluation and Comparison) approach (see also Fischer et al. (2012a)). Avalanche scenarios, based on observations at the avalanche test site Ryggfonn (Norway), serve as input for the comparison. This approach allows a direct and objective comparison of: (1) variations in the model output due to input changes, (2) different models or (3) field measurements. Two dimensional peak pressure distributions serve as main input and are used to automatically calculate indicators like run out distances and other flow dynamical variables. The objectively analyzed and visualized results show how an avalanche engineer can easily compare the main results for different initial scenarios and models.