Storms impact on morphodynamics of human controlled coastal features in western France: the prevailing role of local management practices.

International audienceOn the western coast of France some storms have a dramatic impact while others have almost none. Some sites were insensitive to storms until the 50ies and are, today, retreating. This paper trys to explain why. First we sort out which storms are responsible for retreat and second we search for any change in management practices on the sites. The erosive storms are not always the most powerfull ones (high wind speeds or high waves) but the ones which occur during the peak of high spring tides and have long period waves. The sites which retreat are the ones which were maintained and rebuild, for economic reasons after each small storm event and which, today are let to themselves as they have no more economic activities and are turned into “natural areas”. Therefore the sensitivity of these sites to storm is human-induced. Though they may be even more sensitive if the observed evolution in storminess (namely the increasing frequency of clusters of storms) appears to be a real trend