A. Muauz, B. Berehanu and H. Bedru
The study used the SWAT model to analyze water budget components in the Upper Awash River sub-basin. Data spanning 1986 to 2013 underwent calibration from 1988 to 2008, preceded by a three-year warm-up period, followed by validation over five years at two gauging stations. Sensitivity analyses utilized t-stat and p-value, while model uncertainty was assessed using p-factor and r-factor indices. Model performance was evaluated with NSE, R2, and PBIAS. Calibration and validation produced p-factors and r-factors of 0.801, 0.9 for Hombele, and 0.808, 0.98 for Melkakuntro. R2, NSE, and PBIAS values during calibration were 0.82, 0.82, -2.3 for Hombele, and 0.79, 0.78, -13.1 for Melkakuntro. Validation values were 0.71, 0.67, 11.2 for Hombele, and 0.7, 0.66, 1.9 for Melkakuntro. The average annual groundwater recharge rate varied from 0 to 904.3 mm, totaling 181.1 mm/yr constituting about 19.1% of mean annual precipitation. The simulated mean annual surface runoff and evapotranspiration in the Upper Awash sub-basin were 93.4 and 682.5 mm, respectively. These accounted for 9.8% and 71.8% of themean annual precipitation, respectively. These findings offer valuable insights into the water system of the Upper Awash River sub-basin, enhancing our understanding of its complexity. This information can support sus tainable water management practices in the area.