Abstract : Mountain rivers often carry a large amount of sediment in the process of flash floods and cause severe deformation of the riverbed. In particular, the riverbed of the wide and narrow rivers is adjusted sharply and the water level rises sharply, which can easily increase the risk of flood inundation in the widened rivers. The study of water and sediment transport and riverbed deformation in the evolution of mountain torrents is of great significance for flood control and disaster mitigation. In t