In this research, the deposition zones of 11 snow avalanches that occurred on 22nd and 23rd of January 2021 in the Upper Soča Valley, were recorded using UAV. Point clouds, digital orthophoto (DOF) and digital surface model (DSM) were created based on these images, to determine the runout, volume (from 19,740 m3 at v Koritih avalanche to 542,741 m3 at Komar avalanche) and the height of the deposited debris (from 8.23 m at Peščenk avalanche to 25.22 m at Komar avalanche) in the runout zones. According to the results of calibration runs of the Flow-Py model (maximum values of the SI indicator from 0.810 at the Mesnovka avalanche to 0.983 at v Koritih avalanche), the optimal values of the input parameters for the two clusters of avalanches were determined. They were determined by cluster analysis according to the values of the energy line angle, where the goodness-of-fit indices reached a maximum. Two factors that have a key influence on the classification were identified with logistic regression, namely the proportion of potential release areas within the watersheds and the average longitudinal slope of the avalanche path. In the second phase modelling, which included all the avalanches, optimal values of the energy line angle α = 39.5⁰ for the first group and α = 29⁰ for the second group were used. The result of the second phase modelling based on the optimized input parameters is an avalanche hazard map of the Upper Soča Valley.
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