IMPACT OF THE SURFACE STRUCTURE ON THE BED STABILITY OF STEEP STREAMS

摘要

In this study, the recently introduced roughness parameter s (standard deviation of the roughness heights, see Aberle et al., 1999) is used for the determination of incipient motion in steep streams. Relationships for the critical conditions following the Shields-parameter and the Schocklitsch type of approach are modified with the use of experimental data. The formulated relationships including the geometrical roughness parameters are independent of any grain-size. This is in agreement with the results of Parker et al. (1982), who found that the beginning of motion of bed material with a wide gram-size distribution is not dependent on only one grain size.