Rip channel patterns on the beach near the mouth of Sele River (southern Italy)

The analysis oflong-term measurements carried out on the coast of Sele River, located on the western margin of southern Italy, showed a rather articulated morphology of the submerged beach. Along it several channels perpendicular to the shoreline were found, which affecting the original bars parallel to the shore, thus they have shrunk dramatically. These channels are developed mainly between 0 and 5 meters deep and, according tothe sedimentological characters, play a significant role in the seaward transport of sediments removed from the bottom. More specifically, the bars are constituted by fine and relatively unsorted sands, while the channels are characterized by the presence of sandy and sorted sediments. The increased size of the sediment in the channels as well as its better selection correlates well to the high hydrodynamic energy of flowing water in the channels probably modeled by rip currents. The presence of these currents has been confirmed by some bathymetric surveys. Therip currents are also responsible for the morphological changes of the emerged beach and of the typical rhythmic shoreline, with alternating embayments separated by cusps. The embayments are located in correspondence of the head of rip channels, while the cusps laid out at the bars edges, on which the incident waves break. The rip currents erosion on the seabed extended over the inner portion of the emerged beach, causing erosion processes on the dune and discontinuity in the dune system. Such discontinuitiespromote the genesis of blowouts and parabolic dunes on the beach, that can be the first sign of severe erosion of the coastal system, which is already quite evident in the investigated coastline.