The present study investigates the need to consider the modifications of the waves fields by the ambient water- depths and currents for sediment transport computations with the TELEMAC modelling system. The application is dedicated to the outer Seine estuary (France, English Channel). The wave propagation module TOMAWAC is coupled with the bidimensional horizontal circulation module TELEMAC 2D. Times histories of depth-averaged mean currents and waves heights are compared with field data collected in the access channel to the harbour of Le Havre. Predictions exhibit a local increase by 30 % of the wave height induced by the current. The sensitivity study compares numerical results issued from SISYPHE integrating hydrodynamics of uncoupled and coupled TOMAWAC – TELEMAC 2D simulations. Computations are performed considering successively suspended transport of cohesive mud and bedload transport of sand. The effect of the hydrodynamic coupling is analysed through the variability of the total maximum wave and current bottom shear stress, the maximum suspended sediment concentration and bedload transport rates and the resulting seabed evolutions.