INFLUENCE OF LATERAL BED SLOPE ON EROSION-DEPOSITION PROCESSES IN SUSPENDED-SEDIMENT DOMINATED RIVERS

Present study aims to investigate the influences of lateral bed slope and turbulent diffusion on the erosion and deposition processes in suspended sediment dominated rivers. An expression of erosion term in bank region, which is composed of mass conservation equations for sediment in fluid body and bed layer, is derived based on the mechanism of sediment transportation by turbulent diffusion. Lateral profile for the sediment concentration which yields two peaks is derived theoretically from a depth integrated convection equation in an idealized flow field. Results of numerical computation on bed evolution suggest that the ridge due to sediment deposition is formed in bank region, erosion area is produced at the inside of the ridge corresponding to the peak sediment concentration, and a flat sediment deposition area takes place due to sediment transpot by turbulent diffusion in the channel center as well. The proposed modified erosion term amplifies such lateral bed morphology.