A Short Review on Various Techniques for Measuring Stream Bank Soil Erosion Strength

Stream bank erosion manifests in two main modes, namely mass failure and fluvial erosion. Fluvial erosion is a quasi-continuous entrainment of individual soil grains or grain flocs or chunks from the bank face due to the hydrodynamic shear flow action. It occurs under water with retreat lengths in millimeter or centimeter scale. The interaction between fluvial erosion and mass failure determines the shape and retreat rate of the stream bank. It is not rare, fluvial erosion which occurs at the bank toe later triggers slumping of soil mass known as mass failure. Despite its importance, the mechanism of fluvial erosion is less understood. This is predominantly due to lack of technique for measuring two key bank soil parameters that determine fluvial erosion rate, e.g., erosion shear strength $\tau_{C}$ and erodibility coefficient M. The main purpose of this manuscript is to provide a short review on various techniques for measuring $\tau_{C}$ and M proposed and applied in previous studies. The advantages and limitations of each technique are discussed to get a glimpse on where we stand and what challenges remain to be overcome.