Understanding coastal flood risk prevention by combining modelling and sketch maps (Mediterranean coast, France)

Abstract

ABSTRACT An interdisciplinary approach combining modelling and sketch maps was adopted in order to study coastal flooding risk in the town of Leucate on the French Mediterranean coast. Hydrodynamic modelling was used for reference maps. This innovative approach proposed three types of sketch mapping, covering historical coastal flooding, flood hazard areas, and no-flood hazard areas. Only 55% of the respondents agreed to draw at least one sketch map, demonstrating the difficulty of the exercise, and respondent maps show a global underestimation of the risk. The respondents mainly identify the risk of coastal flooding along the seafront (overtopping), but do not take into account potential overflowing on the lagoon side. Locally, experience of recent flooding in a district impacts on the perception of the coastal flooding hazard. The sketch maps were also analysed by considering two variables: district of residence and residential profile. As expected, the results highlight that the people living in the most exposed areas have a better perception of the hazard than those who are less exposed or who do not live in these areas. First- and second-home residents show very similar hazard mapping, however.