The study estimates the snow cover area for four major basins in the Himalayan region viz. Chenab up to Akhnoor, Ganga up to Devprayag, Satluj up to Bhakra and Beas up to Pandoh using IRS - IC and ID WiFS data. Snow cover estimation was done for the years 1997-2000 using image processing system ERDAS Imagine. The maximum and minimum snow cover extent for the month of September-October and March-April were delineated and on the basis of these the depletion curves for each basin was made for the four years. This output is useful for carrying out snowmelt runoff modeling.

Snow cover measurements are difficult and estimates are not reliable, cheap or easy because of hostile climatic conditions. Conventional methods have limitations in the monitoring of snow covered areas in the Himalayan basin because of inaccessibility. Distributed hydrological models, which can account for the spatial variability of basin physiography and meteorological inputs, have the potential to exploit detailed snow cover data, including distributed snow cover area (SCA).

Remote sensing has been used to provide distributed information characterizing the snow cover of a basin and the information obtained through it has been integrated into snowmelt runoff models. The study uses IRS-WiFS data, which has been found useful for snow cover mapping of large basins as it has the ability to present a temporal dataset to overcome the cloud. The snow cover area (SCA) and the permanent snow cover area (PSCA) have been mapped.

The results indicate that a major portion of the basin is covered by snow in the month of March or April that goes on reducing as the snow melt progresses. The snow cover is minimum in the month of September or October.    

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