Impact of Climate Change on Future Water Availability in Chitral River Basin using Regional Climate Models

The Chitral River, a vital tributary of the Indus River originating from the Hindu Kush Himalayan region, is a key source of water for domestic, agricultural, and hydro power needs in Pakistan. Its flow is predominantly governed by snowmelt, glacial runoff, rainfall, and groundwater baseflow, making it highly sensitive to climate change. This study investigates the impact of climate change on future water availability in the Chitral River Basin (CRB) using the Soil and Water Assessment Tool (SWAT) model and Regional Climate Models (RCMs) under RCP4.5 and RCP8.5 emission scenarios. Bias-corrected climate projections indicate significant warming in the basin, with temperature increases ranging from 2.34°C to 5.23°C by the late 21st century. Changes in precipitation are projected to range from 2.42% to 6%, varying across scenarios and timeframes. These shifts in climate variables are expected to alter the hydrological regime, with peak stream flow's anticipated earlier in the year, from June to July. Model simulations suggest an increase in mean annual flow by up to 19.24% under RCP4.5 and 20.13% under RCP8.5 during the mid-century (2041–2070). However, a decline in flows is projected in the late century due to diminishing glacial reserves, highlighting the transient nature of increased runoff driven by glacial melt. This research underscores the critical need for adaptive water resource management strategies to address the impacts of climate change. The findings provide valuable insights for policymakers, water resource managers, and stakeholders, emphasizing the importance of sustainable practices and integrated watershed management to ensure long-term water availability in the Chitral River Basin and downstream regions.