TOPOGRAPHICAL INFLUENCE ON PRECIPITATION DISTRIBUTION IN DIFFERENT RANGES OF WESTERN HIMALAYAS

Seasonal and annual distribution of rainfall and snowfall with elevati on has been studied for outer, middle and greater Himalayan ranges of Chenab basin in the western Himalayas. Rainfall and snowfall exhibited different trends with elevation on the windward and leeward slopes of the three ranges of Himalayas. Seasonal characteristics of rainfall h ave shown a spill over effect on leeward side during winter, pre-monso on, and post-monsoon seasons in the outer Himalayas. The role of orogr aphy in the middle Himalayas was found to be more pronounced for both rainfall and snowfall in comparison to other ranges of Himalayas. Vari ation of snowfall with elevation was more prominent in comparison to v ariation of rainfall. In the greater Himalayan range it is found that rainfall descreases exponentially with elevation and snowfall increase s linearly. Rainfall becomes negligible at elevations beyond 4,000 m o n the windward side of the greater Himalayan range. Efforts have also been made to explain whether variation in precipitation is due to chan ges in precipitation intensity or number of precipitation days or a co mbination of both.