Selection of CMIP6 climate models and future climatic projection in the Gandaki River Basin, Nepal

Identifying representative general circulation models (GCMs) is essential for improving the accuracy of future hydrological projections under climate change, especially for effective water resource management. This study selects a subset of representative GCMs for the Gandaki River Basin (GRB) using an advanced envelope-based approach and applies bias correction through quantile mapping. Four GCMs, each under SSP2-4.5 and SSP5-8.5 scenarios from the CMIP6 dataset, were evaluated. Under SSP2-4.5, projected annual precipitation changes range from −3.58 to 48.26%, while SSP5-8.5 indicates a broader range from −1.25 to 83.12% across the near future (2026–2050), mid future (2051–2075), and far future (2076–2100) periods. Similarly, temperature is projected to rise by 0.57–2.49 °C under SSP2-4.5 and by 0.45–5.41 °C under SSP5-8.5 for the same periods. The results suggest more intense warming and precipitation under the high-emission SSP5-8.5 scenario, highlighting the increased likelihood of extreme hydrological events. Incorporating these projections into planning enhances the resilience of hydropower infrastructure and water management systems, supporting adaptive strategies under future climate uncertainty.