Hydrological modeling in the Upper Blue Nile basin using soil and water analysis tool (SWAT)

Abstract

Hydrological models are essential to understand the hydrological response of the basin. It is one of the most significant aspects of water resources management and development programs at the small catchment or basin level. A semi-distributed, physical-based hydrologic modeling system, SWAT, was used to model the hydrological responses of the Upper Blue Nile basin. The model was calibrated and validated using the sequential uncertainty fitting (SUFI-2) algorithm in SWAT-CUP. The coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), and percent of bias (PBIAS) were used to measure the performance of the model. The value of R2, NSE, PBIAS was range from 0.81–0.85, 0.68–0.83 and − 10.8 to (− 4.7%) during calibration and 0.89–0.93, 0.88–0.89 and 8.3–9.7% during validation period, respectively. The results indicated a strong correlation between the observed and simulated streamflow during the calibration and validation periods. The overall hydrological water balance analysis showed that 49.5% of precipitation is lost by evapotranspiration, while 22.43% of precipitation is contributed to streamflow as surface flow. Furthermore, the hydrological water balance components of the basin showed a good spatial correlation. Since the water resource planning and management need the temporal and spatial water resource information, the results of this study will be used as a guide for the proposed water resource development projects of the basin.