USING CONSTANT DISPERSION COEFFICIENTS TO SIMULATE THE TRANSPORT IN TIDALLY-INFLUENCED BEACHES

Improvements on the traditional convection-dispersion equation for simulating solute transport in aquifers were made over the years. These include the usage of scale-dependent dispersivities and fractional integration. These improvements, however, were based on situations where the flow is unidirectional. There are no theories for dealing with the transport in highly variable (in space and time) environment, such as in tidally-influenced beaches. In this work, we argue that using velocity-dependent dispersion coefficients is not theoretically sound, and we used constant dispersion coefficients in the two-dimensional model for water flow and solute transport in variably-saturated media, MARUN (Boufadel et al., 1999, J. Contaminant Hydrology, 37, 1-20). The numerical results agree with published experimental results on solute transport in beaches.