Projected hydrological responses to climate change in a high-mountain river basin based on RCM simulations

Abstract

Abstract This study assesses future hydrological responses of the Chitral River Basin (CRB), a high-mountain, glacier-fed catchment in northern Pakistan, under climate change. The Soil and Water Assessment Tool (SWAT) was forced with bias-corrected outputs from three CORDEX regional climate models under Representative Concentration Pathway 4.5 (RCP4.5) and Representative Concentration Pathway 8.5 (RCP8.5) scenarios for the period 2010–2099. Projected temperature increases range from 2.34 °C to 5.23 °C by the late century, while precipitation changes vary between 2.42% and 6%. These changes induce a shift in seasonal streamflow, with peak discharge advancing to June-July. Simulated streamflow responses indicate that warming may alter seasonal runoff timing through enhanced snow and ice melt processes. However, because the adopted SWAT configuration assumes static glacier area, projected late-century reductions should be interpreted as climate-driven hydrological responses rather than direct simulations of progressive glacier depletion. The results highlight substantial uncertainty in future annual flow magnitude across climate models and bias-correction methods, while consistently indicating sensitivity of runoff timing to climatic warming. These findings underline the need for adaptive water-management strategies in the Chitral River Basin.