Relationship between bed shear stress and suspended sediment concentration: annular flume experiments

In this study, annular flume experiments were carried out, using the sediment samples collected from the lower part of the inter-tidal zone at Xiaoyangkou, Jiangsu coast, China. The Ariathurai-Partheniades equation was used to determine the bed shear stress, by evaluating variations in the suspended sediment concentration within the water column. The derived relation between the bed shear stress and suspended sediment concentration shows that, at various stages of seabed erosion, suspended sediment concentration increases rapidly when the flow velocity is increased, but the pattern of change in the bed shear stress does not follow suit. At low concentrations, bed shear stress initially increases markedly with increasing flow velocity. However, when the concentration reaches an apparently critical level around 0.55 kg m(-3), the rate of change in the bed shear stress abruptly slows down, or becomes almost constant, in response to further increases in the flow velocity. Results of experiments indicate that, from a critical level onward, suspended sediment concentration has a strong influence on the bed shear stress.