NEAR SHORE MORPHODYNAMIC OF DRAINED BEACHES

Abstract

The paper deals with a morphological study on a drained beach, under different wave conditions. The Beach Drainage System (BDS) should artificially increase beach infiltration capacity by installing a drain under the beach face. The system produces a water table lowering and, consequently, an increasing of unsaturated zone (Damiani et Al.,2009); moreover, a vertical infiltration flow increases effective weight of grains, producing a better stability. According to the above hydrodynamic effect BDS should influence cross shore sediment transport in the shore zone. Many BDS prototypes have been installed around the world; also in Italy some examples are available, i.e. Ostia (Damiani et Al.,2003), Alassio and Procida (Vicinanza et Al.,2009). Field monitoring is very useful to assess the effectiveness of the system, even if with uncertainties in results, affected by the impossibility to control the boundary conditions. Laboratory tests (Damiani et Al.,2009) could be used in defining how does the system work in different wave conditions and drain configurations.