Medium-term dynamics of a Middle Adriatic barred beach

Other literature type English OPEN
Postacchini, Matteo ; Soldini, Luciano ; Lorenzoni, Carlo ; Mancinelli, Alessandro (2017)

In the recent years, attention has been paid to beach protection by means of soft and hard defenses. Along the Italian coasts of the Adriatic Sea, sandy beaches are the most common landscapes and around 70&thinsp;% of the Marche-Region coasts (central Adriatic), is protected by defense structures. The longest free-from-obstacle nearshore area in the region includes the beach of Senigallia, characterized by a multiple barred beach, frequently monitored during the last decades. The bathymetries surveyed in 2006, 2010, 2011, 2012 and 2013 show long-term stability, confirmed by a good adaptation of an analyzed stretch of the beach to the Dean-type equilibrium profile, though a strong short-/medium-term variability of the wave climate has been observed during the monitored periods. This suggests a slight influence of wave forcing on the long-term profiles, which seems to only depend on the sediment size. Further, the medium-term dynamics of the submerged bars and their geometric features have been related to the wave climate collected, during the analyzed temporal windows, by a wave buoy located 40&thinsp;km off Senigallia. An overall interpretation of the complete dynamics, i.e. hydrodynamics (buoy data), sediment characteristics (equilibrium-profile <i>A</i> parameter) and morphodynamics (bathymetric surveys), suggests that the wave climate is fundamental for the morphodynamic changes of the beach in the medium term: waves coming from NNE/ESE, characterized by a larger/smaller steepness and by a larger/smaller relative wave height, induce seaward/shoreward bar migration, as well as bar smoothing/steepening. Moving southeastward, the bar dimension increases, while the equilibrium profile shape suggests the adaptation to a decreasing sediment size in the submerged beach. This is probably due to the presence of both the harbor jetty and river mouth North of the investigated area.
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