Integration of the risk of heritage loss into the vulnerability assessment of the South Brittany coast (France): implications for coastal vulnerability analysis

Abstract In a context of relative sea level rise, coastal societies are more and more concerned with the increasing threat of shoreline retreat. In the same time, climatic changes, over different time and space scales, lead to new interrogations in regards to risks assessment: risks evaluations as well as risks adaptation and management have to be reviewed. To evaluate the degree of coastal vulnerability resulting from shoreline retreat, current studies apply a geographic economic approach which attempts to attribute a monetary value to anthropogenic components located on the coast. According to this method, the vulnerability of the coast is generally defined as a function of its monetary value. Consequently, such an approach does not allow for the integration in the analysis of the risk of no famous archaeological heritage losses, which are considered, in this paper, as anthropogenic objects with no monetary value for society but which nevertheless represent objects of scientific interest and a source of knowledge. This paper proposes to assess in which extend the introduction of the no famous archaeological sites could impact coastal vulnerability analysis. To doing so, a method has been performed, allowing to analysis coastal vulnerability in South Brittany with and without taking into account the risk of archaeological loss. Results put forward that the integration of the risk of heritage losses when mapping coastal vulnerability could increase the vulnerability of the coast and the stretch of coastline which has to be protected. This simple observation leads to more complex discussions dealing with coastal vulnerability analysis. Firstly, it highlights the fact that the degree of vulnerability likely to characterize the coast is highly dependent on the definition of the anthropogenic features incorporated in the analysis. Consequently, coastal vulnerability analyses appear very subjective. Secondly, it put into evidence that the number of archaeological sites to protect can increase with time when the coast retreats. The location of these sites can hardly be established before the coasts have retreating. This last point contributes to increase the uncertainties associated with risks assessment in a context a global changes. In such a context, we assume that a dynamic coastal management approach such as adaptive management is needed to coop with this increasing complexity.