The coastline or shoreline is the geographical boundary between sea and land. It corresponds according to the SHOM to "the leash of the highest seas in the context of an astronomical tide of coefficient 120 and under normal weather conditions (without overcost phenomenon). The coastline as defined above is not directly identifiable continuously on the ground or on a satellite or aerial image. From a perspective of studying the displacement of the shoreline, indicators allow us to approach this notion (the vegetation limit associated with the infrastructure limit, the beach limit, etc.).

On the reef shoreline of Reunion Island the limit of vegetation and infrastructure as well as beach limit were retained. This limit results in the production of a line-type vector geographic information layer in a GIS resulting from photo-interpolation on the orthophotos of IGN also called BD ORTHO. BD ORTHO is a component of the RGE®. These are digital color orthophotos supplied in raster format (tiff, ecw, ..). An orthophotography is a digital image that has the same metrics as a map of the same projection for the same elements on the ground. They have been available since 1997 in Réunion with a five-year repeatability. Their spatial resolution increased from 1 m in 1997 to 50 cm in 2003.

UMR Espace-Dev