Abstract: A numerical model for non-equilibrium sediment transportis developed based on Reynolds averaged two-phase flow equations. Differentfrom most of the previous models, the present one does not require anempirical formula to deal with the pick-up and settling of sediment over thebed. The model includes the interactions between particles, and betweenfluid and particles. The two-phases are coupled through the interphaseforces. The model is employed to predict the longitudinal variation of thesediment concentration profile over an eroding bed under a steady uniformflow. Computational results agree reasonably well with the availableexperimental data and are evidently more accurate than the analyticalsolution. The relevant turbulent diffusion and gravity settling are alsodiscussed.