A simple quasi-3-D model of suspended sediment transport in a nonequilibrium state

Abstract

A new simple model to evaluate quasi-3-D suspended sediment transport in a non-equilibrium state has been developed through a formulation based on a kind of weighted residual concept. The model includes only two unknown variables to be solved in a horizontal 2-D domain ( x, y); i.e., the sediment concentration at the bottom C b( x, y, t) and the shape factor A( x, y, t) in the assumed exponential curve for the vertical profile of the concentration, both of which are the most important factors governing the nonequilibrium sedimentary process. From the computational results for the 1-D deposition and erosion problems, the model has been confirmed to give satisfactory results in accuracy and in computational time. The present model has also been applied to the 3-D suspended sediment transport problem in the nearshore region including the surf zone. The comparison between the computational results by the present model and those by the conventional models assuming the local equilibrium concentration profile and the nonequilibrium but vertically uniform profile, have demonstrated the importance of taking the effect of the nonequilibrium 3-D condition into the consideration for such problems.