Incipient motion of cohesionless sediments on riverbanks with ground water injection

This study investigates the influence of ground water injection on the initial movement of non-cohesive sediment particles on a riverbank slope analytically and experimentally. By including the hydraulic gradient in the force analysis, the critical condition was derived to account for the effect of seepage flow, showing that the seepage hydraulic gradient and the riverbank slope are governing parameters in modifying the incipient motion of sediments on a riverbank slope. Experimental investigations were performed in an open-channel flume for various riverbank slopes and hydraulic gradients of injection, showing that the critical shear stress increases with decreasing riverbank slopes and vise-versa, while injection reduces the critical value. All experimental data agree well with the theoretical derived expression of the critical condition in the case of injection.