Effect of warmer climate on the depletion of snowcovered area in the Satluj basin in the western Himalayan region

The effect of warmer climate on the depletion of snow-covered area has been evaluated for the Satluj River basin located in the western Himalayan region in India. Snowmelt runoff contributes substantially to the annual streamflow of this river. In order to study the impact of three warming scenarios (T+1, T+2 and T+3degreesC), more than 160 new snow depletion curves were prepared for different elevation zones of the basin over a study period of nine years (1985/86-1990/91 and 1996/97-1998/99). For each zone, the relationship between the cumulative melt and snow-covered area was established and used to obtain the snow depletion curves under warmer climate. Projected snow depletion curves at the basin scale were derived by synthesizing the effect of warming for all zones. Warmer climatic conditions accelerate the melting of snow resulting in faster disappearance of seasonal snow cover from the basin. For the study basin, acceleration in depletion of snow-covered area is computed to be 20, 31 and 40 days for T+1, T+2 and T+3degreesC scenarios, respectively, by the end of the ablation season. The impact of warmer climate on accelerating the depletion of snow-covered area is found to be higher in the early and late parts of the ablation season. The consequences of faster disappearance of snow from the basin are discussed in terms of the hydrology and climatology of the basin