GIS based Estimation of snow depth in mountainous Himalayan region: A case study

High reflectance in visible region and large spatial extents of seasonal snow in Indian Himalayas allow it to play important role in deciding the climatology and hydrology of Indian sub-continent. There is high spatial variability in seasonal snow cover in Himalayan in terms of the areal extents and various snow characteristics. Morphological evolution of snow cover takes place as a result of the snow deposition during various snow storms and thermo dynamical processes within snow pack. Stability of snow over a mountain slope is of importance for various recreational, developmental and transportation activities. Large mass of snow moving downhill (i.e. Snow Avalanche) can affect adversely all these activities and thus affect economy of nation. Stability of snowpack over a mountainous slope is governed by various snow, meteorological and terrain parameters. Snow depth is one of the important variable that contribute significantly in the avalanching of snow loaded slope, given favorable terrain parameters. To assess the avalanche hazard potential, accurate modeling of snow depth is necessary. In the present study, a GIS based method for estimation of the snow depth in a part of North-West Himalaya has been attempted. A hybrid method was adopted for the estimation of the snow depth to cover the limitation of limited observatory network in Himalaya. Firstly, a model factor () is calculated to establish the relation between snow depth at observation points and their elevations in the study area. Snow depth is calculated at each pixel of study area using snow depth of known observation points, model factor(), weight factors and DEM. MODIS satellite data is used to restrict the snow depth maps to snow covered areas only. Snow depth maps for one winter period 2007 to 2008 were generated and analyzed. Snow depth data of Automatic weather stations (AWS) installed in study area were used for validation. Correlation values of around ~ 0.9 have been found between modeled and measured data. Limits and limitation of the method have been discussed. The study reveals that regular monitoring of snow depth near avalanche prone areas along with other terrain and meteorological information can provide valuable inputs for snow pack stability assessment that serves as an important input to avalanche forecasters.