Modeling and Assessing Surface Water Potential Using Combined SWAT Model and Spatial Proximity Regionalization Technique for Ungauged Subwatershed of Jewuha Watershed, Awash Basin, Ethiopia

Abstract

Surface water potential is the availability of water on the surface of the Earth. It is a finite renewable resource, of which the quantity and quality are both space- and time-dependent. Careful estimation of the surface water potential of a river basin is very essential for the future development of any kind of water-related project in countries like Ethiopia. The surface water potential of the ungauged subwatershed of Jewuha watershed was estimated using the hydrological model of Soil and Water Assessment Tool (SWAT) and simple regionalization techniques. The study used different data inputs collected from various sources and field observations. The performance of the hydrological model was analyzed using performance checker parameters. After calibrating and simulating using observed flow, the model showed it was very well to simulate the hydrology of the watershed with a coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), and percent of bias (PBIAS) of 0.74, 0.73, and 0.80 for calibration and 0.71, 0.70, and 7.90 for validation, respectively, in Jewuha watershed. From the total watershed area of 680 km2, 163.68 million m3 of runoff was generated by the model annually. In conclusion, the watershed has high surface water potential, and the rivers in the subwatershed also have enough surface water that may be used for agricultural development.