Research Note «Incipient Motion of Sediment in a U-shape Rigid Boundary Channel

Sediment transport is one of the essential aspects in hydraulic design of rigid boundary channels. Urban drainage systems, irrigation canals and other water transport systems are examples of rigid boundary channels. Channel cross-section shape is one of the effective parameters in sediment transport in rigid boundary channels. In this experimental study, incipient motion of sediment in a U-shape rigid boundary channel is investigated. Experimental data are analyzed based on critical shear stress and critical velocity approaches and new relationships for computing required shear stress and velocity for initiation of sediment motion are presented. The developed relationships are compared with corresponding models available in the literature for loose and rigid boundary channels. It is found that in rigid boundary channels, sediment particles require lower incipient shear stress and velocity in comparison with loose boundary channels. Comparison of incipient motion relationships based on critical velocity approach in rigid boundary channels indicates that among U-shape, circular, rectangular and rectangular with V-bottom cross-section channels, higher incipient motion velocity is required for U-shape channel.