Abstract: In order to guide the cofferdam construction, hydraulic characteristics of the river channel are simulated and analysed during the closure operation. After the verification of the one-dimensional mathematical model with hydrological data collected from Xiajiang hydrological station and the measured water level during the water control project construction, a two-dimensional numerical model is developed to simulate characteristics of waters around the water control project. The flow patterns around the closure berm are quantitatively calculated, the rariation characteristics of flow field and effects of local flow patterns on the closure berm especially the cofferdam are analyzed, and the research results are compared with the physical model tests. And then the results of the double closure berm are compared to these of the single closure berm. The results indicate that the two-dimensional mathematical model can accurately simulate the local water level and flow field the cofferdam, and that the closure construction scheme of the Xiajiang hydroproject is feasible and suitable.