Xynthia : leçons d’une catastrophe

Chauveau, Étienne; Chadenas, Céline; Comentale, Bruno; Pottier, Patrick; Blanlœil, Amandine; Feuillet, Thierry; Mercier, Denis; Pourinet, Laurent; Rollo, Nicolas; Tillier, Ion; Trouillet, Brice

doi:10.4000/cybergeo.23763

Cited by 33 publications

(17 citation statements)

References 3 publications

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“…europa.eu/environment/nature/natura2000/index_en.htm) but also in the context of global mapping of saltmarshes (http:// data.unep-wcmc.org/). Coastal marshlands are vulnerable habitats with regards to anthropogenic pressures (Lee and Yeh, 2009), natural hazards (Chauveau et al, 2011) and rising sea levels (Kirwan et al, 2010). The mapping of coastal habitats appears thus essential for risk assessments as maps can be used to monitor the vegetation structure and to evaluate management impacts.…”

Section: Introductionmentioning

confidence: 99%

Use of bi-Seasonal Landsat-8 Imagery for Mapping Marshland Plant Community Combinations at the Regional Scale

et al. 2015

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International audienceCoastal marshlands may provide ecosystem services but their vegetation and related services may be impacted by environmental changes. Habitat mapping is a key step to monitor the spatio-temporal dynamics of vegetation and detect on-going changes. However, it is still a challenge to produce reliable vegetation maps at the regional scale. This study aims to evaluate the potential of new Landsat-8 imageries (acquired in September and December 2013) for mapping fine-grained plant communities in coastal marshlands. Fieldbased vegetation maps were collected for 270 km of marshlands along the French Atlantic coast. In order to be identifiable on the satellite image, fine-grained vegetationunits were aggregated into fewer plant community combinations. The classification accuracy was assessed by comparison with field-based vegetation data and compared between the supervised methods used, including Minimum Distance, Mahalanobis, Maximum Likelihood, Random Forest and Support Vector Machine. The best result was obtained with the Maximum Likelihood classifier and by combining the twoLandsat-8 images (85.9 % accuracy overall). Three main habitat types dominated the coastal Atlantic marshlands: croplands, Trifolio maritimae-Oenantheto silaifoliae geosigmetum and Puccinellio maritimae-Arthrocnemeto fruticosi geosigmetum. The reliability of the vegetation map produced will provide a good basis for monitoring the conservation status of the various habitats

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Section: Introductionmentioning

confidence: 99%

Use of bi-Seasonal Landsat-8 Imagery for Mapping Marshland Plant Community Combinations at the Regional Scale

et al. 2015

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“…23 Variable of « knowledge reliability » comes from survey results and is according to state services. 24 Variable from IGN data of 2006 (BD Topo Version 'Pays' 1.2) 25 The modalities of the variable « Time of the first discussions » can be: Before the PPR project, At the prescription time of PPR, After PPR prescription.…”

Section: Independence Tests Resultsmentioning

confidence: 99%

Coastal hazards mapping: which obstacles prevent the stakeholders from reaching a consensus?

2016

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Abstract. The development of risks prevention plans frequently causes lively debates between state services (which conduct risks prevention plans and prior hazards studies) and relevant territorial authorities. The development of coastal risks prevention plans, identified as priorities after Xynthia storm in 2010, also faced hard difficulties. Debates mostly concerned coastal hazards mapping process, realized before the plans which strongly depend of them. A questionnaire survey of state services focuses on around sixty coastal hazards studies, concerning coastal flooding, coastline recession and sand dunes migration. The results define territories characteristics (current issues in territory and future territorial development), technical studies characteristics, project management and dialogue process between stakeholders. Chi-square tests of independence highlight major causes to encountered difficulties during dialogue process about coastal hazards mapping process. Current issues in territory don't generate difficulties. However, territories with a high development and where prevention plans could bring constraints are places of conflicts about coastal hazards maps. Encountered difficulties during hazards mapping participatory process is also correlated to the complexity level of studies.

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“…Ce facteur entraîne logiquement l'occupation croissante d'espaces qui sont naturellement soumis à l'influence d'aléas naturels. On en trouve des exemples partout : sur l'atoll de Tarawa dans l'archipel des Kiribati (Pacifique central), où la flèche sableuse instable d'Eita-Bangantebure connaît une forte croissance démo-graphique du fait de populations venues des atolls ruraux vers l'atoll capitale (Duvat et al, 2013) ; la baie de Saint-Paul sur la côte ouest de l'île de La Réunion, qui a connu une densification importante de population entre le XVIII e siècle et aujourd'hui ; ou encore des zones de cuvettes, telles que celle de La Faute-sur-Mer en Vendée, qui a été fortement affectée par la tempête Xynthia en février 2010 (Chauveau et al, 2011 ;Vinet et al, 2012).…”

Section: Facteur 1 : La Conquête D'espaces Exposés Aux Aléas Météomarinsunclassified

La fabrique des catastrophes « naturelles »

Magnan

Duvat

2015

Nat. Sci. Soc.

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On observe depuis quelques décennies une aggravation des impacts humains et économiques des phénomènes naturels. On attend par ailleurs un renforcement des événements dits extrêmes dans le contexte actuel du changement climatique. À l'interface entre sociétés et nature, les auteurs de cet article s'interrogent sur ce que l'impact croissant des phénomènes naturels dit de nos sociétés, tel un miroir où nous reconnaissons les liens distendus entre l'humanité et son environnement naturel, la perte de notre mémoire collective face aux réalités des risques environnementaux, et finalement la persistance de notre vulnérabilité en dépit de notre technologie. Un texte qui invite à nous engager dès maintenant sur la voie pragmatique de l'adaptation aux changements en cours, rappelant que cela n'est pas hors de notre portée. La RédactionRésumé -Ce texte s'attache à mettre en évidence les causes profondes de la vulnérabilité des sociétés aux aléas naturels en exposant les facteurs et les processus qui transforment un simple phénomène naturel en catastrophe. À partir de trois études de cas (le tsunami de 2004 aux Maldives, Katrina en 2005 aux États-Unis, Xynthia en 2010 en France), les auteurs montrent le rôle de quatre grands facteurs, identifiés comme étant universels, dans la fabrique des catastrophes « naturelles » : la conquête d'espaces exposés aux aléas météomarins, la dégradation des zones tampons naturelles, le « mythe du développement sûr » et la perte des liens que les sociétés entretiennent avec leur environnement.Abstract -The making of "natural" disasters. To contribute an explanation for the increasing number of natural disasters, occurring especially in coastal areas, this paper highlights their root causes, i.e. the drivers and processes that make natural events, such as storms or tsunamis, turn into disasters due to the adverse impacts they have on human societies. Based on case studies, the authors identify four key and universal factors driving the generation of natural disasters throughout the world: the settlement of areas that are highly exposed to natural hazards, the degradation of natural buffers, the "myth of safe development" and the loss of environmental knowledge. The three case studies presented here illustrate the processes by which these drivers produce a "risk system" that will make a natural hazard generate a natural disaster: Tropical Cyclone Katrina in the United States (2005), the Xynthia Storm in France (2010) and the Sumatra Tsunami in the Maldives (2004). Based on the lessons learnt from these case studies, this paper outlines key principles for action, arguing in particular that tackling the root causes of current vulnerability is therefore a pragmatic pathway to implement adaptation to climate change.

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Xynthia : leçons d’une catastrophe

Cited by 33 publications

References 3 publications

Use of bi-Seasonal Landsat-8 Imagery for Mapping Marshland Plant Community Combinations at the Regional Scale

Use of bi-Seasonal Landsat-8 Imagery for Mapping Marshland Plant Community Combinations at the Regional Scale

Coastal hazards mapping: which obstacles prevent the stakeholders from reaching a consensus?

La fabrique des catastrophes « naturelles »

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