Sidewall shear stress distribution effects on cohesive bank erosion in curved channels

A series of experiments were conducted to reveal the effects of the sidewall shear stress distribution (SSSD) on homogeneous cohesive bank erosion processes in a U-shaped flume. The three-dimensional flow velocities were measured in detail and the turbulent kinetic energy method was employed to estimate the SSSD. The experimental results showed that the SSSD changed with the discharge and the point of the maximum shear stress varied within a range of 0.15-0.75 of the relative water depth. The variation of underwater bank topography was found to be consistent with the SSSD and the location of the maximum erosion point was not at the bank toe. The dominant failure mechanisms were observed to be tensile and toppling failures. Furthermore, a simplified bank erosion model (SBEM) was developed with consideration of the SSSD. Compared with the bank stability and toe erosion model, the SBEM can provide a more accurate simulation of bank erosion processes. This study is expected to enrich general understanding of cohesive bank erosion processes in curved channels, which will help to formulate effective strategies for river regulation.