The marine flooding hazard along the western coast of Cherbourg Peninsula (Manche, France): a dynamic approach using both numerical modeling with LIDAR data

The sea level rise due to climate change and the recent extreme storms increased the consciousness of coastal hazards and disasters in many areas in the world. The SURCOTE project, which is a part of the LITEAU program, aims at studying the flood hazard along the western coastline of the Cotentin Peninsula. Topographic LIDAR (Light Detection And Ranging) surveys provided static flood-inundation hazard maps. Nevertheless, this approach tends to overestimate the extension of the submerged area without taking into account the flooding processes. To improve the assessment of the submerged surface, a dynamic study is conducted focusing on three areas. The hydrodynamic model TELEMAC is used. Several scenarios were tested from the current sea level conditions (MHWS level and centennial level) to the sea level in 2100 (centennial level plus 1 m). Moreover, failures of protective hydraulic structures (tidal gates, sea defence structures) and breaches in dunes were simulated. In this paper, a comparison is made between the static and the dynamic approach. The influence of the protective structures is evaluated. Finally, the sensitivity of the results to the calculation parameters is assessed.