Analytical Approach to Calculate Rate of Bank Erosion

Bank erosion consists of two processes: basal erosion due to fluvial hydraulic force and bank failure under the influence of gravity. Because bank resistance force varies with the degree of saturation of bank material, the probability of bank failure is the probability of the driving force of bank failure being greater than the bank resistance force. The degree of saturation of bank material increases with river stage; therefore, the frequency of bank failure is correlated to the frequency of flooding. Consequently, the rate of bank erosion is due to both basal erosion and bank failure, and bank failure is a probabilistic phenomenon. In this paper, for cohesive bank material experiencing planar bank failure, a deterministic approach was adopted for basal erosion analysis, whereas the probability of bank failure was included in the analysis of bank failure. A method for calculating the rate of bank erosion was derived that integrates both basal erosion and bank failure processes, and accounts for the effects of hydraulic force, bank geometry, bank material properties, and probability of bank failure.