Use of a Regional Approach for Long-Term Simulation of Snow Avalanche Regime: a Case Study in the Italian Alps.

A method for long-term simulation of snow avalanches is developed, based on coupling statistical interpretation of triggering snowfall process and regional avalanche data. The case study area is the Alta Valtellina region, in the northern Italian Alps. Therein, a 21-year-long series of daily snowfall data from 21 snow stations is used to calibrate a daily point snowfall statistical model. Then, a data set including 68 avalanche events from six historical avalanche sites are used to evaluate regionally valid features of avalanche release probability, geometry, and runout. These findings are then used to set up a model for the occurrence of avalanches. One particular case study site is considered, the Vallecetta mountain, of interest because of the considerable number of avalanche events occurring there. Long-term simulation of daily snowfall is performed, which is then fed into a model of snow avalanche occurrence. Snow avalanche simulations are then carried out, resulting in synthetic statistics of avalanche geometry, volume, and runout for a return period of 300 years. These are compared with regionally observed statistics in the considered area, resulting in acceptable agreement. The proposed model allows long-term simulations of avalanche occurrences for evaluation of snow avalanche volume and runout, usable for ecological and geomorphologic purposes. Integration with an avalanche dynamics model would provide long-term avalanche hazard assessment for land use planning purposes. [ABSTRACT FROM AUTHOR]