The role of particle shape on pebble transport in a mixed sand and gravel beach (Portonovo, Italy)

A better knowledge of the relationship between sediment characteristics and sediment transport is crucial to establish the suitability of fill material for gravel nourishments. In this paper pebble transport is investigated by means of RFID passive tracing technology. Tracers were injected in a small portion of a mixed sand and gravel beach separating sphere from disc shaped pebbles. Tracer recovery was undertaken 6 and 24 h after the injection and wave characteristics were measured during the whole experiment duration. After 6 h the marked pebbles already covered significant displacements with a prevalent longshore component which became evident after 24 h. According to statistical analyses (T-tests and box plots) no significant difference among the displacement of different shapes resulted. The swash zone proved to be the most dynamic area of the beach where all the pebble displacements took place. Because of their higher dynamic, spheres are preferred to discs for nourishment purposes