Sediment system in watershed is not only sediment yield but also including sediment transportation along the rivers. In this study, the Geographic Information System (GIS) combined with sediment yield model can be enhancing the evaluation of soil erosion estimation. Surface erosion on Managawa river basin is computed with the Modified Universal Soil Loss Equation (MUSLE) and it is verified to reflect the hydrological processes be able to estimate soil losses. In the sediment transport routing module, total load equation is applied to carry sediment from soil surface erosion to deposit in Managawa dam. According to annual accumulation sediment volume data in Managawa reservoir during 1981-2003, the establish model and simulation results are satisfy. The efficiency of the Modified Universal Equation with sediment routing in rivers is more than the simple Modified Universal Equation.