Variability and Trends in Temperature, Rainfall, and Discharge in a Western Himalayan Catchment

Abstract

Temperature, radiation, precipitation, and stream flow are all critical climatic variables that affect the ecosystem. Understanding the complex mechanisms involved in climate change is a concern for scientists because it is likely to exacerbate current food shortages and issues with irrigated agricultural systems across the world. Therefore, the current research aims to quantify the long-term variability and patterns in temperature, rainfall, and discharge in a catchment of the western Himalayan region in the state of Himachal Pradesh over a four-decade period. Temperature, rainfall, and discharge trends were studied using Mann–Kendall and simple linear regression models. The investigation revealed that the rainfall amount in the catchment has not changed significantly during different seasons as well as annually. However, temperature trends in the basin demonstrated a slight increase during all the seasons but only the winter season temperature has demonstrated a significant positive change. Conversely, these warming reflections on the water discharge have not been observed accordingly and a significant decline was detected in the annual, seasonal as well as monthly streamflow pattern of the catchment. The shifting nature of rainfall, less snow cover in the lower and middle reaches, and thinning of small glaciers and ice patches over the study period can all be blamed for the decreasing discharge. This reduction in streamflow will influence the hydropower production in the upstream parts and agricultural activities in the downstream areas and thus affecting local as well as the national economy.