CR 57:19-44 (2013)  -  DOI: https://doi.org/10.3354/cr01153

Vulnerability of sandy coasts to climate variability

Déborah Idier1,*, Bruno Castelle2, Marc Poumadère3, Yann Balouin1, Raquel Bohn Bertoldo3, Frédéric Bouchette4, Faiza Boulahya1, Olivier Brivois1, Daniel Calvete5, Sylvain Capo2, Raphael Certain6, Elodie Charles1, Eric Chateauminois7, Etienne Delvallée1, Albert Falqués3, Paul Fattal8, Manuel Garcin1, Roland Garnier9, Arnaud Héquette10, Philippe Larroudé11, Sophie Lecacheux1, Gonéri Le Cozannet1, Mohamed Maanan8, Cyril Mallet1, Aurélie Maspataud10, Carlos Oliveros1, Martin Paillart12, Jean-Paul Parisot2, Rodrigo Pedreros1, Nicolas Robin6, Marc Robin8, Emmanuel Romieu1, Marie-Hélène Ruz10, Jérôme Thiébot1, Charlotte Vinchon1

1Bureau de Recherches Géologiques et Minières, Direction DRP, 3 avenue C. Guillemin, 45060 Orléans cedex 2, France
2Environnements et Paléoenvironnements Océaniques et Continentaux, Université Bordeaux I, avenue des Facultés,
33405 Talence, France
3SYMLOG, 262 rue St Jacques, 75005 Paris, France
4GEOSCIENCES, CC 60 Université Montpellier 2, 34095 Montpellier cedex 5, France
5Universitat Politècnica de Catalunya, C/ Jordi Girona 1-3, Modul B4/B5, despatx 103, 08034 Barcelona, Spain
6Centre de Formation et de Recherche sur les Environnements Méditerranéens, UMR5110, Université de Perpignan Via Domitia, Bat.U, 52 avenue Paul Alduy, 66860 Perpignan cedex 9, France
7BRLi, 1105 avenue Pierre Mendès France, BP 4001, 30001 Nîmes cedex, France
8Littoral - Environnement - Télédétection - Géomatique, UMR CNRS 6554, Pôle Mer et Littoral, Université de Nantes, BP 8122, 44312 Nantes, France
9Escuela Técnica Superior de Ingenieros de Caminos de Caminos, Universidad de Cantabria, Avenida de los Castros s/n,
39005 Santander, Spain
10Laboratoire d’Océanologie et de Géosciences, UMR CNRS 8187, Université du Littoral Côte d’Opale, 32 avenue Foch,
62930 Wimereux, France
11Laboratoire des Ecoulements Géophysiques et Industriels, BP 53, 38041 Grenoble cedex 9, France
12Communauté de Communes de l’Île de Noirmoutier, BP 714, rue de la Prée au Duc, 85330 Noirmoutier-en-l’Île, France

ABSTRACT: The main objective of the VULSACO (VULnerability of SAndy COasts to climate change and anthropic pressure) project was to investigate present day and potential future vulnerability of sandy coasts at the 2030 horizon, i.e. on a time scale related to climate variability. The method, based on a multidisciplinary approach bringing together geologists, geographers, physicists, social psychologists, engineers and stakeholders, was structured around 4 axes: field data analysis; numerical modelling; analysis of governance and stakeholder perceptions; and development of vulnerability indexes. This approach was designed to investigate vulnerability at a local scale and was applied to 4 contrasting beaches located in France: Sète Lido (Mediterranean Sea), Truc Vert and La Tresson beaches (Atlantic Ocean), and Dewulf (English Channel). The results focus on decadal and multi-annual beach trends at the Truc Vert beach site. There is almost no trend in beach volume at Truc Vert beach, although there is a variation in this parameter on a cycle of 2 to 3 yr, with variations related to wave energy and probably to indexes of climate variability. Numerical modelling identified the sensitivity of beach responses to changes in wave height and direction, especially in terms of subtidal morphology and the potential development of shoreline instability. Together with the observed offshore wave angle at the Biscay Buoy, these model results suggest that a potential change in wave angle due to climate variability could significantly modify the bars’ morphology. The combination of data analysis and numerical modelling contributed to the development of vulnerability indexes designed for sandy coasts, which take into account climate-dependant variables such as waves. This allowed the differentiation of the sites in terms of vulnerability to erosion: Sète Lido and Truc Vert beach were the most and least vulnerable sites, respectively. These indexes help in identifying the dominant components of beach vulnerability, and provide potential for the study of how anthropogenic factors affect vulnerability. The study of stakeholder perceptions and decision-making with regard to climate-related risk  also highlighted potential anthropogenic effects on beach vulnerability, and identified possible site-specific outcomes.


KEY WORDS: Sandy beach · Modelling · Field data · Stakeholders · Index · Truc Vert · France


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Cite this article as: Idier D, Castelle B, Poumadère M, Balouin Y and others (2013) Vulnerability of sandy coasts to climate variability. Clim Res 57:19-44. https://doi.org/10.3354/cr01153

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