Stabilisation d’un cordon de galets par des rechargements : l’exemple de la plage de Nice-Côte d’Azur (France) / Stabilization of a pebble bar by nourishment : the example of Nice Côte d’Azur beach (France)

The development of tourism and transport infrastructures in Nice, on the French Riviera, has seriously affected the sediment dynamics and stability of the grave) barrier beaches bounding Nice Bay. Beach erosion has been more or less controlled since 1976 through artificial nourishment, using grave) obtained at little or no cost. Statistical analysis of beach width and nourishment volumes has enabled precise delimitation of sectors that have accreted following nourishment and those still subject to erosion. Persistence of the three erosional sectors is basically due to uneven distribution of the recharged material, to episodic torrential activity by small mountain streams emptying into the bay, and to the presence of small but active submarine canyons impinging on the beach . Two principles for optimising nourishment are presented. These are sustained nourishment at present levels (around 20 000 m/yr) and, especially, improvement of the spatial distribution of the recharged grave), favouring, in particular, the sectors most prone to erosion.