Sorted bedforms developed on the north Catalan inner shelf

Swath bathymetry and backscatter data and sediment samples are used to characterize the sorted bedforms developed on the north Catalan continental shelf (NW Mediterranean Sea). The sorted bedforms are located in the inner shelf, at water depths ranging from 10 to 40 m. They develop over fine sand deposits that extend from the shoreline to the seaward limit of the infralittoral prograding wedge. The sorted bedforms are characterized by a subtle relief (<0.4 m) and an elongated shape, with an orientation nearly perpendicular to the shoreline. They display lateral symmetry in backscatter and bathymetric relief with high backscatter centred on the depressions. The sorted bedforms are composed of well-sorted fine to medium sand in the topographic highs and poorly sorted coarse sand in the bathymetric lows, where ripples can develop. At decadal scale, these bedforms appear as persistent features, showing small changes in their boundaries. Their development is related to the local contribution of sediment by ephemeral streams. The accumulation of fine-grained sand over the coarse domain of the infralittoral prograding wedge contributes to the bed sediment heterogeneity, which is further reorganized by currents to form the sorted bedforms.