Climate change impacts on snow cover dynamics and hydrological regimes in the Chitral River Basin, Pakistan

ABSTRACT A significant portion of Pakistan's snow accumulation occurs within the Indus Basin watershed. In the Upper Indus Basin, river discharge is primarily driven by a combination of glacier and snowmelt. Snowmelt contribution to runoff is particularly crucial in mountainous regions, making accurate estimation of snowmelt runoff essential for effective water resource management in Pakistan. This study assesses hydro-meteorological parameters in the Chitral catchment using historical data from the Pakistan Meteorological Department and the Water and Power Development Authority. It analyzes their impact on the snow-covered area (SCA). The Snowmelt Runoff Model was applied to evaluate the hydrological response of the snow-fed catchment to climatic variations. Findings indicate that during the historical period (1981–2015), the maximum temperature (Tmax) increased by 0.20 °C per decade, while the minimum temperature (Tmin) declined by 0.02 °C per decade. Annual precipitation increased by approximately 39.2 mm per decade. Streamflow in the catchment rose by 10.93% over the 1991–2015 period, likely due to rising temperatures and enhanced summer monsoon precipitation. Average SCA showed seasonal variation, with an approximately 26% increase in winter and a 27% decrease in summer. Analysis of hydrological and climatological data from the Chitral basin revealed strong correlations among SCA, temperature, and streamflow, highlighting the basin's dependence on snow and glacier melt. Understanding the impacts of climate change is therefore essential for water resource management, particularly in a country like Pakistan, where diverse climatic conditions amplify vulnerability to climate variability.