Author(s): Remi Dumasdelage; Olivier Delestre; Didier Clamond; Arnaud Bonnin; Michael Moretti; Patrick Ceruti; Philippe Gourbesville
Keywords: Gravel beach; Coastal erosion; Numerical Model; TELEMAC2D; TOMAWAC; SISYPHE
Abstract: In Nice, the urbanization process associated with the natural configuration of the beach (a steep inner shoreface and a narrow zone of concentrated wave breaking) is the main cause of an important loss of gravels. Studies have demonstrated that this erosion reaches 15, 000m 3 /yr. The municipality has started a nourishment campaign since 1960 and in total more than 500, 000m 3 of gravels have been brought. In order to characterize the solid transport along Nice shore, the hydrodynamic forcing terms due to the waves and the currents have been modeled using the TELEMAC hydroinformatic system. With the sea-state model TOMAWAC, we show that the submarine caps create zones of wave energy concentration. Moreover, by coupling this module with the hydrodynamic model (TELEMAC2D), we provide details about the current along Nice Bay. Thus, the wave incident angle changes the currents direction from East-West to West-East depending on the bay location. The modeling of the sediment transport combined with the previous results demonstrates that the eastern beaches are exposed to important sediment losses when experiencing swells coming from different directions (SE, SW, S). Comparisons between beach width measurements and the present results show the accuracy of the model. Nevertheless, the variability of the sediment transport being very important in Nice, further measurements (beach profile after and before a storm) have to be carried out.