EFFECT OF CLIMATE CHANGE ON POTENTIAL EVAPOTRANSPIRATION IN THE UPPER BEAS BASIN OF THE WESTERN INDIAN HIMALAYA

Abstract. Appraisal of potential evapotranspiration (PET) is needed for estimating the agricultural water requirement and understanding hydrological processes in an arena. Therefore, aim of the paper was to estimate the PET in the upper Beas basin, situated in the Western Indian Himalaya, under future climate change scenarios (by mid-21st century). Climate data (1969–2010) of Manali, Bhuntar and Katrain were obtained from India Meteorological Department (IMD) and the Indian Agricultural Research Institute (IARI). Landsat data were used for mapping land use/land cover (LULC) conditions of the basin through decision tree technique. Elevation detail of the catchment area is derived from the Cartosat-1 digital elevation model (DEM). Simulations of PET were done by the Soil and Water Assessment Tool (SWAT) model. The model was calibrated using the average monthly discharge data from Thalout station. The study found fluctuations in PET under different climate change scenarios. It is likely to increase in near future owing to the rise in temperature. The higher water demand can be met from the excess snowmelt water reaching the lower basin area during the cropping seasons. This study will be helpful to understand water availability conditions in the upper Beas basin in the near future.