Abstract:
The mountains cover a large portion of the Earth surface. As the mean altitude of the land area of the Earth is 875 in above sea level, and therefore over 28% of the land areas are above 1,000 m. In these high mountains, it is estimated that 10 to 20% of the total surface area is covered by glaciers while an additional area ranging from 30 to 40% has seasonal snow cover. There are of course variations in depths of snow and ice from place to place depending on the location. Snow forms a natural reservoir, storing water for weeks or months; if properly harnessed it can be used for water supply, agriculture, and industry and energy production. The majority of rivers originating from the Himalayas have their upper catchment in the snow-covered areas. The solid precipitation results in temporary storage and this storage supply water in the river system during snowmelt season. Snow cover measurements are difficult and estimates are not reliable, cheap or easy because of the hostile climatic conditions and the remoteness of the areas. Conventional methods have limitations in the monitoring of snow covered area in the Himalayan basins because of inaccessibility. Due to the difficulty of making field measurements in snow-covered mountainous regions, remote sensing is attractive tool as a means of estimating snow-cover properties. Snow and glacier melt runoff is very important, particularly, in lean season and it plays a vital role in making nearly all the rivers originating in Himalayas which are perennial. Keeping in view the importance of snow cover area, in this study remote sensing methods have been applied for mapping of snow cover area. Snow starts melting just after winter season is over, i.e., in the month of March and reaches minimum after monsoon season. Snow cover depletion curves have been prepared to show the trend of melting of snow.
