INVESTIGATING THE USE OF PLEAIDES IMAGERY TO DERIVE COASTAL DUNE TOPOGRAPHY

Topographic data are widely used to monitor morphological changes over coastal areas and can be collected through different methods and techniques. DGPS data (Harley et al., 2011), airborne LiDAR data (Sallenger et al., 2001), and more recently, satellite imagery (Almeida and al., 2019) can be used to derive Digital Elevation Models (DEMs) for coastal studies. DEMs- derived from DGPS data have usually the best resolution (± 50 cm) and vertical accuracy (± 3 cm), but have a small beach coverage (few kilometers). Airborne LiDAR data offers a relatively good spatial resolution (1 m), an average vertical accuracy (± 10-15 cm) and cover hundreds of kilometers but are costly and thus cannot be often carried out. Until recently, the spatial resolution of satellite imagery was not adapted to study meter scale morphological changes in coastal studies. The emergence of high spatial resolution imagery captured by satellites such as Pleiades-1, WorldView 2/3/4, GeoEye- 1, etc. offers the opportunity to study coastal topographic changes with a relatively good resolution (from 0.5 to 1 m) over large spatial areas and at repeated times. The potential use of Pleaides satellite images to monitor coastal dune topographic changes along the south west coast of France is explored here.