Morphological Development and Evolution of Barchanoid Dunes on the Cap Ferret Coastal Spit

Abstract Barchans are crescent-shaped dunes with their convex side facing the wind and their horns pointing downwind, commonly observed in deserts but also in coastal environments. This study investigates the dune field of the Cap Ferret Spit (5-km wide, 23-km long; Atlantic Coast, SW France) including of series of barchanoids dunes, currently stabilized by forest cover. The aims are to classify each dune into distinct typologies and characterize their morphology in order to analyze their evolution. LiDAR-based analysis identified four distinct barchanoid dune types. Moreover, it revealed superimposed bedforms on the dunes, including draping and oscillating patterns, reflecting the influence of consistent wind regimes during dune development and migration. This study proposes an evolutionary sequence in which proto-barchans evolve into barchanoid ridges and eventually as mature isolated barchans. These findings provide insight into the geomorphological evolution of barchanoid dunes in a coastal context, and particularly their migration pattern on a coastal spit system.