A new GIS modelling of coastal dune protection services against physical coastal hazards

International audienceCoastal dune management presents a unique problem to coastal scientists, not only because of thedynamic and complex nature of coastal dune systems but also because of the protection service againstmany coastal hazards such as storm surges in low and flat coastal countries, shoreline retreat, and aeolianerosion. In order to evaluate such a service, a new GIS modelling of a coastal dune protection service hasbeen carried out on Noirmoutier Island. It is based upon geoinformation coming from LIDAR, Spotsatellite and aerial photography data processing. This paper discusses the Geographic InformationSystem (GIS) methodology used for data acquisition and analysis and presents a methodology developed(i) to characterise and map dune shapes using geoindicators in order to highlight aeolian deflation,marine coastal erosion and marine submersion over the long-term and (ii) to set up a transferable andsynthetic methodology. This methodology is based upon spatial syntheses computed in regular50 m*400 m boxes built up landward from the shoreline. Each variable is integrated within each box.This allows to quantify (i) spatial occurrence of each variable and (ii) spatial coincidence of many variableswithin each box. Each protection service is underlying by a set of variables. The state of theprotection service is then discussed and quantified and can be used by stakeholders to manage dunes ina safe way for society stakes