Snow Avalanche Analysis on Aerial Photographs

Abstract

Results of snow avalanches reflected over the roads in a snowy mountainous area were examined by mesns of aerial photographs.The topographic elements regarding usual courses of snow avalanches were interpreted on the aerial photographs taken in non-snow season, and velocity variation and suspending points of snow avalanches on these courses were calculated with various coefficients of kinetic frictions.On the other hand, the suspending points of svalanches on these courses were observed and measured on the aerial photographs taken in snow avalanch season.By using these results, the coefficient of kinetic friction of snow avalanches in the region was estimated, and velocity, kinetic energy per unit volume and impulsive force per unit area of snow avalanche on the roads were estimated for each course of snow avalanche.Moreover, debris depth and volume of snow avalanche at each course were measured by comparing the aerial photographs taken in deepest snow season against those taken in snow avalanche season.Calculation of velocity, energy and impulsive force and measurement of depth of debris and volume of the snow avalanche at each course in the region will give the rank of the snow avalanche, and will contribute to plan the highway course.