Role of Bank Protection in Channel Erosion in Alluvial Rivers

Bank revetment is usually regarded as an effective way to reduce dam-downstream channel erosion in alluvial rivers worldwide. While existing studies primarily focus on the deformation processes of natural rivers, the impacts of bank revetment remain less understood. This study conducts a flume experiment to investigate the role of bank protection in the channel deformation processes. The results indicate that: (1) obvious local bed scouring was observed near the discontinuous bank boundary in a straight rectangular flume, with the largest scour depth occurring at the transition zone between the protected bank and the natural bank; (2) the local scouring was attributed to high near-bed flow turbulence and velocity gradients caused by discontinuity bank boundary, while adding a smooth transition could reduce the maximum erosion depth by 22%; and (3) bank protection measures tended to shift the erosion direction from the riverbank to the riverbed, but these measures may not significantly reduce the overall erosion rate as commonly expected if the riverbed remained erodible. This study provides insights into bank erosion and effective control measures over a short time and contributes to understanding long-term morphological adjustments of regulated alluvial rivers.