Effect of Inlet Morphology and Wave Action on Pollutant Pathways and Sediment Dynamics in a Coastal Stream

Hydrodynamics and water renewal of intermittent coastal streams are highly variable, at various time scales, due to the very active morphodynamic behavior of their inlets. Due to this strong dynamics, the pathways of water-borne materials — and the consequences of contaminated discharges — can depend strongly on the morphology and environmental conditions. Predicting the fate of contaminants in these systems requires coupled numerical models accounting for the major physical and water quality processes. We aim at improving the understanding of the impact of inlet morphology and wave action on the pollutant and sediment pathways of these small coastal systems, based on a suite of calibrated and validated coupled models. Two analyses, based on particle simulations, are presented to assess sediment dynamics and pollutant pathways for several conditions. Results show that waves have a major effect on the fate of water-borne materials in the estuary. Wave-induced currents sweep away materials coming out of the estuary, while wave-induced setup has a profound effect on tidal propagation, water levels and velocities in the estuary, promoting the upstream transport of pollutants.