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

Abstract

Coastal dune management presents a unique problem to coastal scientists, not only because of the dynamic and complex nature of coastal dune systems but also because of the protection service against many coastal hazards such as storm surges in low and flat coastal countries, shoreline retreat, and aeolian erosion. In order to evaluate such a service, a new GIS modelling of a coastal dune protection service has been carried out on Noirmoutier Island. It is based upon geoinformation coming from LIDAR, Spot satellite and aerial photography data processing. This paper discusses the Geographic Information System (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 and synthetic methodology. This methodology is based upon spatial syntheses computed in regular 50 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 variables within each box. Each protection service is underlying by a set of variables. The state of the protection service is then discussed and quantified and can be used by stakeholders to manage dunes in a safe way for society stakes.