Abstract: The Ω caving in riverbanks is one of the typical bank erosion patterns occurred in alluvial rivers which develops quickly and increases the instability of dikes. The numerical simulation of this type of bank erosion is still a challenging task. The Zhinancun bank caving developed at the lower Yangtze River was investigated in this paper, and a 3-D numerical method for modeling the Ω caving in the riverbank was proposed based on the mechanism of bank erosion. The sediment transport capacity in the circumfluence zone was calculated by considering the influences of turbulence intensity. The simulated results indicated that the velocity close to the riverbed is larger than that in the upper layers in the circumfluence zone during the processes of riverbank collapse, which becomes the driving factors for the riverbed scouring and thus bank erosion. The determination of the sediment transport capacity has a great influence on the simulated shape of the bank which can be more accurately simulated by considering the effect of turbulence intensity. This study could improve our understanding of the mechanism of riverbank collapse.