Swash platform morphology in the ebb-tidal delta of the Barra Nova inlet, South Portugal

Abstract

A fieldwork study of an artificially created inlet cut in the barrier island system of the Ria Formosa (South Portugal) was carried out from January to March 1999. This study focused on the up drift swash platform associated with the ebb-tidal delta. The area was monitored during a month with fair weather conditions studying morphodynamics, sedimentary dynamics and hydrodynamic measurements. The results were used to establish a sedimentary budget of the swash platform and to quantify the morphodynamics. A strong accretion was observed on the swash platform, which corresponded to the volume of sediment provided by the longshore drift on the adjacent updrift coast. A redistribution of sediment was observed on the platform, changing the orientation of the main swash platform axis. The swash bars forming this area are very dynamic (20 m migration in 8 days), and the entire swash platform migrated toward the inlet resulting in progressive closure of the system. Characteristics of the inlet and morphodynamics of the swash platform were used to validate a conceptual model of by passing by ebb-tidal delta breaching for this system.