Calibration and Validation of the SWAT Model for Upper Bernam River Basin in Malaysia

Enhancing sustainable agricultural practices and water resources management calls for this study, which focuses on calibrating and validating the SWAT model using data from CMIP6. The SWAT model was validated using Bernam streamflow data from 1985-2022, divided into three categories: category 1 (10 years calibration- and 5 years validation), category 2 (15 years calibration- and 10 years validation), and category 3. The SWAT model performed "GOOD" in the Bernam watershed, as indicated by statistical analysis during calibration and validation phases, utilizing statistical indices. The results for the p-factor, r-factor, R2, NSE, PBIAS, and KGE were 0.82, 0.88, 0.72, 0.70, -1.1%, and 0.85 during the calibration period and 0.8, 1.04, 0.75, 0.65, -6.6%, and 0.79 during the validation period. The result of the simulation after adjusting the SWAT model parameters with calibrated best-fit values indicated that the inflow (rainfall) and the outflow (water yield + ET) are 2,873.36mm and 2,592.78mm respectively, with difference of 9.8% for the period of 1991-2005 while 2,921.98 mm and 2,586.07 mm for the inflow and outflow, during 2006-2020 period with difference of 11.5%. The SWAT model effectively predicts agro-hydrological processes, aiding decision-makers in UBRB's agricultural water management and guiding sustainable agriculture through advanced climate projections.