Modelling turbidity maximum in the Seine estuary: capacity and limits of atwo-dimensional horizontal model

Without any gravitational effect, a two-dimensional horizontal model simula tes sediment patterns close to those observed in the Seine estuary. This re sult confirms the important role of the asymmetry of the tidal wave propaga tion and justifies the use of a depth-integrated model. But results show pr oblems in long-term simulations of the turbidity maximum and excessive depo sits along the coasts. A three-dimensional model seems to be necessary for mean-term simulations: the salinity gradients mainly act in maintaining the suspended particles in the estuary, while the vertical structure of veloci ties and concentrations help in avoiding the lateral sediment trapping. ((C ) Academie des sciences / Elsevier, Paris.).