Courants induits et dissipation de l'énergie des vagues sur les plages macrotidales de la mer d'Iroise

Several field experiments of both morphological and hydrodynamical measurements occured during springs 2004 and 2005 on four beaches of the Iroise Sea (Finistère). Within these four datasets (sea surface elevation, cross-shore and longshore flow velocities), dissipation of wave energy is investigated through time (accounting with tidal cycle) and space (across the intertidal zone). These results are compared to empirical parametrizations of relative wave height ?s (Raubenheimer et al., 1996 ; Sénéchal et al., 2001), parameter greatly used in hydrodynamic models. Then, the local breaking criteria ?s,b is used to characterize wave-related processes (wave asymetry, breaking-induced undertow) involved in sediment transport in the intertidal zone