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This study aims to better understand coastal processes associated with extreme cyclonic events through the study of the coastal changes, flooding and damage that resulted from the passage of a category 5 hurricane (Irma) on 6 September 2017 over the islands of Saint-Martin and Saint-Barthélemy in the Lesser Antilles. Hurricane Irma was contextualized from tropical cyclone track data and local weather observations collected by Météo-France, as well as high-resolution numerical modelling. Field work involved the study of accretion coasts through qualitative observations, topo-morphological and sedimentary surveys, as well as image acquisition with Unmanned Aerial Vehicle (UAV) surveys during two trips that were made 2 and 8 months after the catastrophe. Wave propagation and flood numerical models are presented and compared to field data. Our field analysis also reports on the devastating impacts of storm surges and waves, which reached 4 and 10 meters height, respectively, especially along east-facing shores. The approaches reveal a variety of morpho-sedimentary responses over both natural and highly urbanized coasts. The analysis shows the effects of coastal structures and streets on flow channeling, on the amplification of some erosion types, and on water level increase. Positive spatial correlation is found between damage intensity and marine flood depth. The signatures of ocean-induced damage are clear and tend to validate the relevance of the intensity scale used in this study.

Purpose The purpose of this paper is to develop a multidimensional approach for effectively managing natural disasters; this paper has three research objectives. First, it provides an analysis on the hydro-geomorphological effects of the cyclone in the urban context. Second, it proposes an analysis for the vulnerability and resilience recovery of the populations living in urban areas. Third, it specifies the implications for sustainable recovery and longer-term disaster risk reduction. Design/methodology/approach A detailed case study of the tropical cyclone Pam was carried out to identify hydro-geomorphologic effects and damages in an urban area and specific problems associated with managing natural disaster in Vanuatu. Findings The investigations reveal that living in an urban area increases a population’s exposure to hydrological, weather and sea-related risks. Whereas advice on cyclones seems to work very well, the coastal risks and floods seem to be underestimated with a very high exposure and vulnerability to risk. Pre-existing vulnerabilities were exacerbated after cyclone Pam. However, other communities have been able to reinforce their resilience through local initiatives. The government and outside aid were very quick to react, despite problems of coordination, exchange of information, communication and long-term strategy. Practical implications The bottom-up, top-down, local and global approaches, applied on the time scales, should lead to actions that will reinforce the ability of the people of Vanuatu to adapt to high-energy events and to the effects of climate change. Originality/value This paper highlights the importance of understanding how the urban communities are vulnerable to natural hazards and of strategies for increasing their resilience.

The deltaic plain of the Petite Camargue which constitutes the western part of the Rhone Delta, began its main progradation around 2000 yr ago. Several delta lobes follow each other and have participated in the deltaic evolution. The deltaic lobes have distinct morphologies which reflect the dynamic fluvial and marine processes under the influence of climatic and human controls. Two delta lobe systems were built by the Daladel and Peccaïs channels, after which a deflected wave-influenced delta lobe was formed by the La Ville and Saint-Roman channels. The latest channel, the Rhone Vif channel, is skewed because this channel was completely canalized and engineered up to its mouth in the beginning of the 16th century. Since the avulsion of this channel about 1550 A.D., the coastline of the Petite Camargue has been especially affected by the influence of waves and currents. The spits replaced the beach ridges which juxtaposed themselves and have migrated westward since the 16th century. The formation of the western part of the delta in the last 2000 yr is affected by not only the fluvial sedimentary fluxes and the coastal dynamics to the mouth but also climatic change and human influence.

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L'interprétation des dépôts fluvio-deltaïques du paléogolfe d'Aigues-Mortes à l'Holocène met en évidence deux lobes marqués par d'importantes discontinuités intra-deltaïques. Leur analyse s'est essentiellement appuyée sur un nouveau référentiel morphologique élaboré par Bhattacharya et Giosan (2003) qui s'avère efficace dans la caractérisation des processus littoraux et fluviatiles. Plusieurs deltas modernes caractérisés par cet indice fournissent un référentiel utile dans la description des formes deltaïques héritées. Le remblaiement du paléo-golfe d'Aigues-Mortes semble postérieur à 2000 BP initié par le chenal de Peccaïs et ses distributaires Chacun d'eux a construit un système d'embouchure à la morphologie bien spécifique en réponse aux processus hydro-sédimentaires dominants : (1) le lobe cuspidé du Rhône de Peccaïs, (2) un lobe à systèmes d'embouchures déviées mis en place par les bras de La Ville, de Saint Roman et (3) du Rhône Vif dont l'activité a été limitée à une vingtaine d'année. L'ensemble de ces éléments permet d'élaborer une série de scénarii paléo-géographiques appuyée par une chronologie revue et actualisée. Ces résultats complètent. les connaissances acquises sur le delta du Rhône jusqu'à ce jour et permettent d'illustrer le comportement deltaïque entre la fin de l'antiquité et le début du Petit Age Glaciaire.

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