The sandy coasts are very dynamic environments at all time and space scales. Today, they constitute an area of strategic importance for humanity because of its strong economic and demographic weight. This thesis aims to study the morphodynamics of the shoreface of the Languedoc-Roussillon region (Mediterranean Sea) at a multi-decadal to secular scale. This work is possible by the use of topo-bathymetric airborne LiDAR able to map large areas. The results of this thesis show that there exist a wide variety of beach and bars states. The organization of these states is mainly controlled by sedimentary characteristics, wave conditions and geological context. The sediment budget of the shoreface was studied at secular scale and indicates an overall deficit of more than 26 million m3 of sediment. Sand bar dynamic was analyzed at a multi-decadal scale and shows the presence and involvement of slightly oblique nearshore bars in the process of Net Offshore Migration. Finally, this thesis has also highlighted the strong influence of human activities on the general shoreface behaviour at the regional scale.
Morphodynamic at regional scale of a microtidal shoreface with nearshore bars: example of the Languedoc-Roussillon coastline using LiDAR technology