The original coastline, that is to say as it was prior to any  reclamation, has been digitalised on the basis of old maps. For the stretches of the coast where there has been no reclamation, we have used recent aerial photographs. This is an overlay (polyline) corresponding to the non-artificialised coastline. Its outline is the basis for the calculation of the artificial coast and that of the surface area of reclamations and of bathymetric ranges.
It is defined on the basis of the ortho data base of the "Institut Géographique National" (IGN) ( resolution 50 cm ) and traced at a scale of 1/10 000 except in the vicinity of the land reclamations where the scale of reference chosen is 1/1 000.

Example of the original coastline at the level of a reclamation from the sea.