SALINITY AND SUSPENDED SEDIMENT DYNAMICS IN RESPONSE TO FORCING CHANGES IN A SMALL MACROTIDAL ESTUARY (CHARENTE, FRANCE)

4 Abstract A three-dimensional numerical model was developed to reproduce the hydrodynamics and salinity dynamics of the macrotidal Charente estuary, located on the French A tlantic coast. The model uses horizontal structured grids and vertical sigma layers. Tidal elevations from a seri es of nested models and river flows are considered for the open boundary conditions. The roughness length and the t urbulent scheme were adjusted in order to better fi t the tidal elevation, currents, and salinity observed on diffe rent locations. The simulations give good results, with a decreasing accuracy when moving upstream. The validated model was used to simulate the impact of the river flow a nd the spring/neap tidal cycle on the salinity intrusion a nd the residual circulation. Sediment fluxes were a lso evaluated from currents simulated in realistic conditions of weath er and river flow, associated with turbidity in-sit u measurements.