Les submersions marines en Manche orientale : approche inductive et naturaliste pour la caractérisation des facteurs responsables des inondations par la mer

Pauline Letortu 1 Stéphane Costa 1 Olivier Cantat 1
1 LETG - Caen - Littoral, Environnement, Télédétection, Géomatique
LETG - Littoral, Environnement, Télédétection, Géomatique UMR 6554
Abstract : Xynthia storm, in February 2010, has left its mark on the French coast of Atlantic Ocean and the English Channel because of its severity (47 people died and about €2 billion in damages). Consequently, the current context gives strong interest in studies about these meteorological and marine phenomena and their weather forecasting/prevention. In this paper, we studied French low coastal areas of the eastern English Channel (Normandy and Picardy coasts) because of their sensitivity to coastal flooding risk. Because of cumulative factors (exposure to strong West wind, beach sedimentary crisis, low altimetry of valleys), the French coast of the eastern English Channel is particularly interesting for analysis of this natural risk. This work has a double objective. The first objective is the presentation of our coastal flooding inventory (from 1949 to 2010) and the detection of a possible evolution about frequency and intensity of coastal flooding events perhaps linked to current climate change. The second objective is the characterization of the different meteorological, marine, and morphological parameters that end in these destructive phenomena. In matching these meteorological and marine factors with the past events inventory, we have identified the dominance of the concomitancy of well-known conditions (strong wind perpendicular to coast and high tide level), reinforced here by the passage of an atmospheric cold front during high tide. But some cases do not follow this logic. To understand them, we have followed step by step the explanation process in adopting inductive and naturalistic approaches. The aim is to highlight other factors that are involved in the process of coastal flooding. This new point of view is based on field observation and the use of different spatial and temporal scales and enables to emphasize "the preparation time" of the beach (lowering of its profile) by meteorological and marine conditions (not necessarily extreme) before the coastal flooding event.
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Submitted on : Thursday, May 2, 2013 - 1:53:21 PM
Last modification on : Tuesday, August 27, 2019 - 11:02:09 AM

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Pauline Letortu, Stéphane Costa, Olivier Cantat. Les submersions marines en Manche orientale : approche inductive et naturaliste pour la caractérisation des facteurs responsables des inondations par la mer. Climatologie, Association internationale de climatologie, 2013, 9, pp.31-57. ⟨10.4267/climatologie.165⟩. ⟨hal-00819803⟩

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