Back-analysis of the 1986 Snow-avalanche Event Related to the Foscac Avalanche Site (Trentino – Alto Adige / Südtirol, Italy) Using the Numerical Model TRENT2D❄

In the night between January 31 and February 1, 1986, during a snowfall, a snow mass of an estimated volume of 31000 m3 was released from the Foscac mountainside (Trentino-Alto Adige/Sudtirol, Italy), thus involving a ski slope and causing damage to several lodges and the Ciampié refuge. The purpose of this study consists in reconstructing this snow avalanche using the numerical model for dense snow avalanches TRENT2Dޡ to verify that it can reproduce real cases. As a preliminary step for the back-analysis, historical testimonies and data concerning the event are collected. Due to the lack of precise information regarding the release, the release area is identified thanks to a cartographic analysis, while the release snow height is estimated by reconstructing the meteorological event that caused the avalanche through the Weather Research and Forecasting model. The back-analysis of the 1986 snow avalanche is then carried out in two stages. The first step consists in performing a sensitivity analysis by changing the model parameters, the release volume, and the position of the release area and by identifying how these variables affect the dynamics of the simulated avalanche. Regarding the second step, the model parameters are carefully calibrated by comparing the numerical results with the historical testimonies and by minimizing the related differences expressed in terms of snow height, involved area and runout distance. The results of the backanalysis of the 1986 Foscac snow avalanche show that the TRENT2Dޡ model can reasonably reproduce snow avalanches accurately.