CS(AR)-38/98-99 : Snow and glacier contribution in the Satluj river at Bhakra Dam

Abstract

The contribution of snow and glacier melt runoff in all the Himalayan rivers originating from Himalayas is very significant. The estimation of snow and glacier melt runoff is required for water resources development of the region. In the present study, the average contribution of snow and glacier melt runoff in the annual flow of Satluj river at Bhakra dam is estimated. This study is restricted to Indian part of Satluj basin. A water balance approach was used to determine the average snow and glacier contribution in the total annual flows. The total water budget of the basin was made for a period of 10 years (Oct. 1986 - Sept. 1996). Rainfall data of 10 stations were used to compute total rainfall input to the basin over the water budget period. Total volume of flow for the same period is computed using discharge data at Bhakra reservoir. Evapotranspiration losses from the basin are taken into account only from the snow free area considering that evaporation losses from the rain falling on the snow covered area and from the snow covered area as well, are negligible. The snow covered area in the basin has been determined using satellite data. It is observed that on average about 65% area of the basin is covered with snow in the month of March/April which reduces to about 20% in the month of September/October. Average snow and glacier runoff contribution in the annual flow of Satluj river at Bhakra is estimated to be about 61%. Evidently, the majority of the stream flow into Bhakra reservoir are generated from snow melt and glacier melt. Even during the monsoon period significant amounts of snow melt and glacier melt are generated from the high altitude region in the Satluj river.