Estimation of the sediment yield using hydrological assessment tool model: a case of Wadi Al-Arab Dam at the northern part of Jordan

Sedimentation represents a serious threat to the dam and reduces its useable water storage and its life span. Due to erosion and sedimentation problems, a dam gradually loses its ability to store water for the purposes for which it was built. The Soil and Water Assessment Tool model (SWAT) was utilized to estimate the sediment yield in Wadi Al-Arab dam at the northern part of Jordan. In this research, two sediment transport relationships were developed: one for the sediment yield as a function of surface runoff and another for the sediment yield as a function of the slope, area of the watershed, and water discharge by using a statistical regression analysis on a set of hydraulic variables. The results showed that the reservoir storage is reduced with an annual rate of 0.093 MCM, and the accumulated sediment occupies 15% of the total storage capacity during a period of 32 years. The model also identified the location of high sediment yield within the study area, which is located at the western part of the watershed. The result of this study was compared with those of other investigators and with the actual sediment data. The difference in sediment yield between this study and actual sediment deposition was about 7%. Based on the results, it was found that SWAT model could be used to predict catchment soil erosion in watershed and sediment yield trapped behind similar dams.