A New Semi-Analytical Method to Calculate the Fluvial Erosion Rate of Non-Cohesive Riverbanks

Fluvial erosion due to hydraulic force and bank failure under the influence of gravity are the two physical processes of riverbank erosion. This paper presents a new, simple, semi-analytical method to estimate the rate of fluvial erosion of non-cohesive riverbanks caused by hydraulic force. The derived equation is built based on the critical flow velocity concept, rather than the commonly used shear stress approaches. Because the distribution of the shear stress of a side wall varies considerably with the side wall's cross-sectional profile, it is difficult to estimate the shear stress distribution along a river bank. In contrast, the cross-sectional contours of flow velocity close to the side wall are parallel to the wall to some extent, which suggests that the flow velocity is more reliable and more easily measured in comparison to the shear stress. Large-scale laboratory experiments were conducted to evaluate the critical-velocity-based model. The calculated results agree well with the measured data. This semi-analytical approach is promising for estimating the fluvial bank erosion rate in the field.