Sediment transport in open channel flow has a significant impact on the siltation of rivers, reservoirs, and artificial channels, and it is one of the major topics studied in the water resources realm. Despite the intensive investigation done in the past, the transport mechanism of sediment particles seems to have reached a stage where further progress may depend on a more comprehensive understanding of the chaotic and intermittent behavior of turbulence instead of the temporally averaged streamwise momentum of a boundary layer that exhibits a smooth profile with no evidence of sharp changes in momentum. Among others, the existence of coherent structures in wall-bounded turbulent flows has been confirmed (