Modeling of the Erosion Phenomena on Nice Shore Face and the Impact of Coastal Structures

Nice, located in the South-East of France, has constantly been developing on an economical and social level for the last decades. Thus, the urbanization process, implying the development of new infrastructures (Promenade des Anglais, roads and railways) has triggered an important erosion of the beach. Nice's neighboring rivers, Var and Paillon, were the primary sources regarding the natural supply of beach gravels. But the combination of the airport construction, at the Var river mouth and the structures all along the streams has stopped the gravel supplies. Those anthropological factors associated to the natural configuration of the beach (steep inner shoreface and narrow zone of concentrated wave breaking) contribute to an important loss of gravel. Studies have demonstrated that the erosion of Nice beaches reaches 15,000. In this context, a modeling approach has been started to characterize the solid transport along the Nice shore. Our goal is also to understand the effect of the structures on the erosion. The TELEMAC-MASCARET system has been chosen for this study. It is a powerful integrated modeling tool which is composed of different simulation modules. TOMAWAC and TELEMAC2D modules are used for this study. The model created on TOMAWAC has provided results regarding the wave propagation in the bay. The simulations demonstrate the existence of high values of wave heights near the coast. This is due to sub-marine caps. TELEMAC2D coupled with TOMAWAC has been used to simulate the current effects along the shore. During South-East storm events, the center part of the bay is exposed to high velocity values, whereas the west part is less vulnerable to this swell. There are two explanations: the orientation of the bay and the groynes.