Assessing coastal flooding hazard in urban areas: the case of estuarian villages in the city of Hyères-les-Palmiers

Abstract : Coastal flooding assessment has considerably improved in recent years, especially thanks to the enhancements in probabilistic approaches and in numerical modeling. This study, conducted on the city of Hyères-les-Palmiers (French Riviera), aimed to evaluate how sea level rise could modify coastal flooding hazards in the urban areas located near small estuaries in a microtidal context. A joint probability approach on 3 variables allowed establishing typical storm parameters associated with specific return periods (30 years, 50 years and 100 years), taking into account both offshore conditions (sea level and significant wave height) and the river level. Storm scenarios have then been established based on these parameters and on the chronology of the most impacting recent storm (rising, peak and decrease of the storm). The sea level rise has been simply integrated, considering a rise of 20 cm for year 2030 and a rise of 60 cm for year 2100. The coastal flooding associated with these different scenarios has been simulated with a non-hydrostatic non-linear shallow-water model: SWASH (Zijlema et al., 2011). The calculations have been realized on high resolution DEM (1 to 5 m mesh size) based on LiDAR data, in order to consider the presence of buildings and coastal protections in the flooding simulation. The simulation approach has been validated by reproducing a recent flooding event in this area. Obtained results show the importance of wave overtopping in current coastal flooding hazard in this area. Nevertheless, if Hyères-les-Palmiers is currently little exposed to coastal flooding, these simulations highlight an increasing role of overflowing due to sea level rise by climate change. Consequently, the results show that some areas should be significantly flooded in 2100, even for quite frequent events. These conclusions should be used by the municipality to guide the future land use planning in the exposed areas. Overview of the overtopping and flooding simulation in Ayguade village: 30 years return period storm in 2030, situation after 8 hours of simulated storm This work has been supported by the Hyères-les-Palmiers municipality and the BRGM.
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Contributeur : Sylvestre Le Roy <>
Soumis le : mardi 4 octobre 2016 - 17:57:24
Dernière modification le : samedi 17 décembre 2016 - 01:04:14
Document(s) archivé(s) le : vendredi 3 février 2017 - 16:11:02


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Sylvestre Le Roy, Alexis Stépanian, Rodrigo Pedreros, Thomas Bulteau, Alexandre Nicolae Lerma, et al.. Assessing coastal flooding hazard in urban areas: the case of estuarian villages in the city of Hyères-les-Palmiers. 3rd European Conference on Flood Risk Management (FLOODrisk 2016), Oct 2016, Lyon, France. ⟨10.1051/e3sconf/20160701010 ⟩. ⟨hal-01376433⟩



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