ABSTRACT
A step-pool morphology is typical for steep streams. Small ratios of channel width to step-forming block size lead to an increase of step stability due to grain interlocking. Rough banks may further contribute to this jamming effect. However, the effect of rough banks on the flow conditions has hardly been considered in the evaluation of bed stability of step-pool channels. Within this study, physical experiments were conducted in a rectangular tilting flume to investigate the effect of rough banks on flow resistance in steep streams. Bank roughness was introduced with rectangular elements mounted pairwise on each side of the flume. The results of this study indicate that flow resistance significantly increases for experiments with rough banks leading to a reduction of bed shear stress. This separate hydraulic effect in addition to jamming may be considered in the assessment of step-pool stability.
