Experimental study on the interaction between bank collapse and riverbed evolution of homogeneous soil

Bank collapse is a sudden change of lateral channel migration, along with the riverbed deformation. The paper presents a study on the process and influence factor of bank collapse and bed evolution of homogeneous soil through a series of experiments carried out in a bend flume. Experimental results reveal a repeat process as follows: Bank collapse after accumulative basal erosion, the failed bank soil remaining at the bank-toe temporarily but soon afterwards being disintegrated and transported by intensified turbulent flow nearby, the coarser soil disintegrated from the bank or the fallen block being dragged to the convex bank downstream as bed load while the finer parts being transported by flow as suspended load, near-bank current structure being adjusted due to bank collapse and bed evolution. The research also reveals that the magnitude of the bank collapse or the riverbed erosion are mainly in proportion to the near-bank velocity and scouring duration, but reverse to the cohesion of material. The amount of bank collapse is larger than that of bed erosion when the channel suffers from erosion. The range of the named relative rate of bed erosion is about 0.40~0.92, decreasing as the amount of bank erosion.