ИСТИНА

A lot of one-dimensional empirical methods for calculating of extreme runout distances based on topographic parameters of the avalanche tracks were performed by snow engineers for different mountain regions of Russia. The main goal of our investigation was to test the capabilities of well-known Russian methods and Swiss avalanche dynamics model RAMMS to back-calculate well-documented avalanches (with volumes from 2 000 up to 2 100 000 m3) in Russia. The most accurate and well-documented data from different powder and wet, extreme rare and small frequent snow avalanche events is collected from 1960th till today in the Khibini Mountains and in the Caucasus. It was digitized and put to the detailed large-scale digital avalanche database (GIS) with more than 50 years of observations for certain avalanche tracks. GIS was used to analyze the initial conditions of avalanches and model input parameters as well as to compare measured parameters with model results. GIS is a unique source of information for understanding avalanche flow rheology and calibration avalanche dynamics models. А new statistical approach for the assessment of the avalanche runout distance return period based on the avalanche release zones clustering was developed using these data. We applied RAMMS to simulate more than 50 well-documented avalanche events and discuss the calibration of the avalanche model friction coefficients in function on the geographical characteristics of Russian mountain regions. Avalanche zoning is not yet used by land planning authorities in our country. Our results can be used for the future development of it in Russia.