Abstract: The Dagu River suffers from the fluvial process in the recent years. A numerical model can be used to minimize the fluvial and flood water levels, and to optimize the water storage and navigation conditions. In this study, a quasi-3D numerical hydrodynamic model and a 3D fluvial model are combined to simulate the hydrodynamic and fluvial processes. The quasi-3D numerical model for the river dynamics shows a great advantage comparing with the 3D numerical model in the computation efficiency while retaining the capability for simulating the vertical distribution of the flow and sediment. Model calibration results show that the model calculated results of the flood stage and total sediment runoff are reliable and reasonable, which can be further used to study the flood control and siltation reduction as well as sediment transport in the Dagu River. These simulation results can provide suggestions for the optimization of the location of the dam, the shape of the embankments, the width of the rubber dam and the optimization of the cross-section of the Dagu River in order to realize the maximum benefit of the flood control, siltation reduction and water storage for navigation.