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Bed-load transport is effective on river bed stability and Morphology. Therefore, modeling this phenomenon is very important in the field of hydraulics engineering. Bed-load transport occurs by saltation at low to medium shear stress and by sheet-flow at high shear stress. In the present paper, the hydrodynamics of transport in thesaltationand sheet-flow regimes under unidirectional flow is studied using a Lagrangian model based on I-SPH method. The fluid and sediment phases are modeled separately as Newtonian and non-Newtonian fluids respectively. Fluid-sediment interaction is modeled using drag force to define interaction mechanism. To calibrate and validate the numerical model, the result is compared with experiments. There is a good agreement between them that illustrates the applicability of the present model in the simulation of both saltation and sheet-flow regimes hydrodynamics.