Advanced Hydrological Modeling of Climate Change Impacts on River Basin Streamflow and Reservoir Sedimentation Dynamics Using CMIP6 GCMs and SWAT Framework

Watershed hydrological systems exhibit profound sensitivity to shifting climatic patterns, precipitation variability, and rising atmospheric temperatures. Altered hydrological regimes directly impact river discharge rates, flood frequency, agricultural irrigation potential, and reservoir sedimentation dynamics, posing severe threats to regional water resource security. This study implements the Soil and Water Assessment Tool (SWAT) model to simulate daily streamflow and quantify upland sediment yield within a major tropical river basin under baseline and projected climate change scenarios driven by Coupled Model Intercomparison Project Phase 6 (CMIP6) General Circulation Models (GCMs). Historical meteorological records, topographical DEM datasets, soil classification maps, and high-resolution land use land cover (LULC) data were utilized to calibrate and validate the hydrological model using Sequential Uncertainty Fitting (SUFI-2) algorithms. Simulation outputs under shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5) indicate substantial temporal shifts in seasonal monsoon runoff peaks and a 16% to 31% acceleration in reservoir siltation rates over coming decades, emphasizing the critical necessity for adaptive watershed management and robust sediment mitigation strategies.