the strong seepage force may result in a higher riverbank scour rate. The formula for riverbank scour rate under seepage force is developed based on an of analysis of forces acting on sediment particles and the experimental data in a rectangle flume by Wang. An example is given to show the application of the formula to riverbank scour rate. It is expected that the formula for bank scour rate can be used to analyze the changing process of riverbank landform and to forecast bank collapse.