Original morphodynamics behaviors of bar-beach systems along the " Plaine Orientale " (Corsica, Mediterranean Sea)
Abstract
Along the east coast of Corsica Island (France), the " Plaine Orientale " (PO) is a 100 km long alluvial low land with a quite regular sandy shoreline, with high recreationnal value, and facing the Tyrrhenian sea, from Bastia to Solenzara. The coast is wave-dominated, with a microtidal regime presents a wide variability of coastal morphologies: single/double barred beaches with crescentic or linear bar systems river mouths, lagoon inlets or sand spits. Such diversity highlights a longshore distribution of several specific morphodynamic behaviors and hence, leads to different exposures to coastal risks mainly locally driven by wave incidence. In order to identify these different morphodynamic behaviors and to monitor the coastal erosion hazard, a long term beach-shoreface topographic survey have been carried out, by the BRGM, French Geological Survey, on different locations of the PO since 2001. Yearly beach profiles and shoreline position measurements are studied in terms of spatial and temporal variability but such data type inhibits the understanding of longshore evolution patterns. During march 2010, a complete bathymetric lidar survey of the PO shoreline has been carried out in order to investigate for the first time the longshore morphology of submarine bars systems and their physical connexion with the shoreline. Thus, an inter-comparison of these multi-scale morphological data with decadal wave conditions allows the investigation of the specific beach morphodynamics patterns along PO coastal linear in term of bar-beach interactions. Morphological characteristics of the various beaches, their exposure, their evolution at a decadal timescale as well as classical parameters (Dean, closure depths,...) are used to propose a classification and analysis of the coastal dynamics at a regional scale.