Spatial Distribution of Rainfall with Elevation in Satluj River Basin: 1986-2010, Himachal Pradesh, India

Abstract

The complex relationship between topography and precipitation in mountainous regions such as Himalayas is evident from the pattern of rainfall distribution. The variation in precipitation with altitude is controlled by mean height of clouds and decrease in water vapours with altitude. Spatially distributed measurements of precipitation have gained renewed interest in connection with climate change impact studies. Precipitation values are usually available from a limited number of gauge stations and their spatial estimates can be obtained by interpolation techniques such as Inverse Distance Weighted (IDW), Kriging and Spline. In the present study, precipitation-elevation relationship can be established using Digital Elevation Model (DEM) (Advanced Spaceborne Thermal Emission and Reflection Radiometer-ASTER, 30m resolution), Spline interpolation technique in Geographical Information System (GIS) environment and point data from various gauge stations spread over the Satluj River Basin. Changes of spatial distribution of precipitation with elevation show a distinct shift. Bhakra Dam (5854.60 mm) to Rampur (4451.10 mm), there is continuous variation in rainfall with increase in altitude. But beyond Rampur, variation is very high. Swarghat shows exceptional rainfall (8031.76 mm), may be due to position of mountains and their orographic effects. Maximum rainfall was observed in the lower Himalayas i.e. Shiwalik range. Negligible rainfall was observed beyond Kaza (470 mm), above the elevation of around 3756 m. The general trend of rainfall exhibits that the lower and middle parts experience good rainfall whereas the upper part experiences less rainfall. Such spatial and temporal distribution of rainfall with elevation provides an important platform for hydrologic analysis, planning and management of water resources.