Transport de sédiments fins dans le bassin de Marennes-Oléron : mise en place d'un modèle mathématique

Fine sediment transport in the Bay of Marennes-Oléron Development of a mathematical model

IFREMER, Centre de Brest, BP 70, 29280 Plouzané, France CETIIS, 24 Bd Paul Vaillant-Couturier, 94200 Ivry-sur-Seine, France

Abstract

The bay of Marennes-Oléron (Atlantic coast, France) is submitted to tides, swells and wind-induced waves. An hydrodynamical and sedimentological model has been developed to compute the effects of these forcings on cohesive sediments. Model and measurements are in good agreement to simulate the turbidity fluctuations during the fortnightly tidal cycle. Adding the effect of wind waves improves the turbidity results within the tidal cycle : this is due to the large tidal flats where small depths allow for sediment resuspension under frequent wind waves action. The sediment budgets are qualitatively in good agreement with observations, but the tide effect seems overestimated. The wave action is likely to partially balance this effect.