Application of SWAT in Hydrological Simulation of Complex Mountainous River Basin (Part II: Climate Change Impact Assessment)

This study aims at analysing the impact of climate change (CC) on river hydrology a complex mountainous basin—the Budhigandaki River Basin (BRB)—using Soil and Water Assessment Tool (SWAT) hydrological model that was calibrated validated in Part I this research. A relatively new approach selecting global models (GCMs) for each two selected RCPs, 4.5 (stabilization scenario) 8.5 (high emission scenario), representing four extreme cases (warm-wet, cold-wet, warm-dry, cold-dry conditions), applied. Future data bias corrected using quantile mapping method. The bias-corrected GCM were forced into SWAT one time to simulate future flows BRB three 30-year windows: Immediate (2021–2050), Mid (2046–2075), Far (2070–2099). projected compared with corresponding monthly, seasonal, annual, fractional differences simulated baseline period (1983–2012). results showed long-term average annual are expected increase all climatic conditions both RCPs baseline. range predicted changes shows high uncertainty. comparative frequency analysis one-day-maximum -minimum increased decreased low future. These imply necessity design modifications hydraulic structures as well preference storage over run-of-river water resources development projects basin from perspective resilience.