Pickup rate of non-cohesive sediments in low-velocity flows

Erosion of sediments is of crucial significance to morphologic evolution, management of water quality and aquatic ecosystems. However, the prediction of the pickup rate of non-cohesive sediments is a challenging topic because of the complex interaction between the bed and the flow. This study reports the experimental results of the pickup rate of non-cohesive sediments in uniform flows. Six groups of uniform sand with diameters in the range of 0.183 mm to 1.090 mm were tested. The pickup rate was measured near the erosion thresholds. The experimental data, along with the data collected from previous studies, are applied to evaluate existing formulae for the grain-by-grain pickup rate. Those commonly used formulae fail to reproduce measurements well at both the high and low entrainment rate conditions. Efforts are made to revise the formula of Cao (1997) to predict the grain-by-grain pickup rate at both the high and low entrainment rate conditions.