Enjeux de l'intégration des espaces naturels littoraux dans la gestion des risques liés à la mer

摘要

Based on two case studies located in French overseas territories, this presentation aims to investigate how to base coastal risk management policies on natural coastal system protection. The in-depth analysis of the impacts of and resilience to cyclones Oli in Tubuai Island (French Polynesia, Feb. 2010) and Bejisa in Reunion Island (Jan. 2014), raised the major role of natural buffers degradation (i.e. sand-dune systems) in increasing vulnerability. Five processes are analysed here: contraction (reduction in land area), fragmentation of sedimentary cells by coastal structures, shoreline fixation due to coastal defences, removal or modification of vegetation and finally, coral beach extraction. These phenomena alter the attenuation function of waves and wind, and finally increase damages when a coastal hazard occurs. This results have concrete implications in terms of enhancing resilience of territories to sea-related risks, enabling to: (1) design and implement conservation and restoration policies so as to strengthen the buffering capacity of sand-dune systems; (2) consider the sediment cell as the relevant scale for coastal risk management; (3) implement context-specific solutions that take into account long-term changes, so as to initiate a climate change adaptation policy.