Two-dimensional mathematical model of water and sediment was adopted to study the infection of erosion on the downstream river in Dadu River after a hydropower station had been built. Some parameters, such as water level, velocity, and erosion depth of river-bed were analyzed in the condition of usual flood.The result showed that rinsing discharge can lead to the adjustment in the downstream river cross-section morphology, the cutting in the overall of the riverbed, the uniform velocity distribution and the significantly decreasing of water level.
