The study aims to assess the impacts of various climate scenarios on the hydrological response of the high altitude Spiti river in the Himalayas. The climatic scenarios were constructed on the basis of simulations of the Hamburg coupled atmosphere-ocean climate model for the study region.

The influence of these scenarios on the snow water equivalent (SWE), snowmelt runoff, glacier melt runoff, total stream flow and their distribution have been studied. The adopted changes in temperature and precipitation ranged from 1 to 3^o C and -10 to 10 % respectively. The following conclusions are drawn from the study:

• Snow water equivalent over the study basin reduces with an increase in air temperature (T+1, T+2, T+3^oC; P+0%). However, no significant reduction in annual SWE is observed for the projected increases in air temperature over the basin. It seems the high altitude and low temperature regime of the basin limited the reduction in SWE. An increase of 2^oC in air temperature reduced annual SWE in the range of 1 to 7 % (T+2^oC, P+0%). The change in SWE was found proportional to changes in precipitation.
• Under warmer climate scenarios (T+1, T+2, T+3^oC; P+0%), snow melt runoff, glacier melt runoff and total stream flow indicate early response along with change in their runoff distribution over time. All these hydrological components linearly increase with an increase in temperature from 1-3^oC. The most prominent effect of temperature increase has been noticed on glacier melt runoff as compared to snowmelt runoff and total stream flow. An increase of 2^oC in air temperature has increased annual snowmelt runoff and total stream flow.
• The snowmelt runoff and total stream flow increases linearly with changes in precipitation, but glacier melt runoff is inversely related to changes in precipitation for different temperature scenarios. It is found that snowmelt runoff is more sensitive than glacier melt runoff to changes in precipitation.

Similar studies should be carried out in basins located in different geographic and climatic regions to investigate potential impacts of projected climate warming on hydrology and water resources in India.

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