Implications of River Discharge Angle and Basin Slope on Mouth Bar Morphology and Discharge Dynamics of Stable Jets

Abstract

River mouth bars are strategic morphological units primarily responsible for the development of entire deltaic systems and coastline configuration. Although many works during the last decades analyzed the effects of factors such as tides, wind waves, or sediment properties, the control that some aspects of the geometrical configuration of the river mouth exerts on the sedimentary processes remains unclear. This paper addresses the role of the receiving basin slope and the river discharge angle in the hydrodynamics of an exiting sediment-laden turbulent jet and in the resulting mouth bar morphodynamics using Delft3D. Keeping all other factors constant, we find that when varying the discharge angle and the receiving basin bottom slope, the turbulent jet changes its direction and spreading rate. We also establish a theoretical framework for the specific morphology of the mouth bar as a function of the river discharge angle and basin slope, highlighting their importance for properly designing managing strategies. Finally, predicted mouth bar morphologies are compared with good agreement to river mouths in real locations.