Variability of Temperature and Rainfall in the Upper Beas Basin, Western Himalaya

Abstract

Temperature and rainfall affect both the spatial and temporal patterns of water availability, especially in the Himalayan environment. Hence, it is imperative to analyse the trends in temperature and rainfall. The present study aimed to quantify the inter-annual and intra-seasonal variability in these climate variables at Manali and Bhuntar of the upper Beas river basin. Daily temperature data, including minimum temperature $(T_{\hbox{min} } )$, maximum temperature $(T_{ \hbox{max} } )$, mean temperature $(T_{\text{mean}} )$, lowest minimum temperature $(L_{ \hbox{min} } )$, highest maximum temperature $(H_{ \hbox{max} } )$, amount of rainfall and number of rainy days of Manali and Bhuntar for the period 1980–2010, were obtained from the India Meteorological Department. The Mann–Kendall and Theil–Sen’s slope nonparametric tests were used for the determination of trends and their magnitude. The findings indicate that the upper Beas basin experienced a warming trend at the rate of 0.031 ℃/year during the period of analysis. Range of temperature showed a significant decline in the basin. Rainfall showed a significant decreasing trend at Manali. The number of rainy days also showed a reduction at Manali during the period of study. Significant variation has been observed in rainfall intensity in the region over the study period. It is not possible to rule out the link between the warming trend and increase in anthropogenic activities in lower part of basin.