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In recent years, attention has been paid to beach protection by means of soft and hard defenses. Along the Italian coast of the Adriatic Sea, sandy beaches are the most common landscape feature and around 70% of the Marche region's coast (central Adriatic) is protected by defense structures. The longest free-from-obstacle nearshore area in the region includes the beach of Senigallia, frequently monitored in the last decades and characterized by a multiple bar system, which represents a natural beach defense. 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- to medium-term variability of the wave climate has been observed during the monitored periods. The medium-term dynamics of the beach, which deal with the evolution of submerged bars and are of the order of years or seasons, have been related to the wave climate collected, during the analyzed temporal windows, by a wave buoy located about 40 km off Senigallia. An overall interpretation of the hydrodynamics, sediment characteristics and seabed morphology suggests that the wave climate is fundamental for the morphodynamic changes of the beach in the medium term. These medium-term time ranges during which waves mainly come from NNE/ESE are characterized by a larger/smaller steepness and by a larger/smaller relative wave height, and seem to 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. [ABSTRACT FROM AUTHOR]

An analysis of the run-up over different beach profiles is performed to evaluate the influence of the seabed shape on shore flooding. The analysis was carried out on the basis of numerical solutions of the nonlinear shallow water equations. The chosen solver was shown to provide reliable (both quantitatively and qualitatively) run-up results by comparing numerical solutions (of both solitary and regular waves) with the only available analytical solution forced by a localized topographic change. The run-up patterns on both a natural beach profile and three simpler and schematic profiles derived from it were evaluated. Different wave conditions (both random and groups) were used for a total amount of 96 different cases of inundation. Results are expressed in terms of both maximum () and steady-state () run-up. It is found that both types of run-up depend on the offshore variable , as suggested by several available studies, and that, for all tested cases, random waves induce the largest compared with the wave groups. The largest is induced by the composite-planar profile for both random waves and groups. An important similarity is found for both and induced by all wave types over the natural and equilibrium profiles, giving further support to the use of an equilibrium profile as representative of the natural profile. Attempts at finding an equivalent planar beach highlight unavoidable difficulties in choosing such a profile and reinforce the idea that the concept of an equivalent planar beach cannot bridge dynamics occurring from the depth of closure to the run-up. More likely, such a concept is only suitable to describe dynamics that are local to the foreshore. [ABSTRACT FROM AUTHOR]

Novel observations of bar features and migration patterns at three Italian sandy beaches in Senigallia (central Adriatic Sea) and Terracina (central Tyrrhenian Sea) are presented. While two of these beaches are unprotected, one is artificially embayed through the presence of a concrete jetty. Bar locations and motions are analysed with video imagery data sets from coastal monitoring stations. Wave climate from the Copernicus oceanographic model is used to correlate hydrodynamics and beach morphology. Clear net offshore migration (NOM) patterns are identified at all beaches, although exhibiting different response scales. At the low-slope beach of Senigallia (mean surf zone slope of 0.009) bars are more sensitive to seasonal changes in wave climate, with offshore shifts in winter and inactivity in summer. Mean annual migration rates of up to 0.26 m/day and 0.09 m/day are observed for outer and inner bars, respectively. No significant response to single storms is observed, except during a single NNE storm. No distinct erosive or accretive trend for the shoreline is evidenced. At the steep beach of Terracina (mean surf zone slope of 0.018), conversely, bars are strongly responsive to single storm events, with displacements of up to 25–50 m across a single storm. The mean inter-annual migration rate is 0.08 m/day for the single/outer bar, whereas a slight onshore trend (-0.02 m/day) for the newborn inner bar is established. The presence of an artificial jetty at the Misa river mouth in Senigallia, finally, leaves the bar system, typically oscillating around an equilibrium position, susceptible to larger seasonal oscillations and strong offshore migration due to two ESE storm events. Numerical simulations of nearshore circulation for two storms from different directions predict the birth of longshore currents, higher ratios of significant wave height to water depth, and stronger bottom orbital velocities over bars in case of the ESE storm, suggesting a greater tendency for offshore-directed sediment transport. • Video-based observations of sandbar dynamics at three microtidal beaches. • All bar systems show offshore-directed migration trends and occurrence of NOM. • Response to seasonal climate at mildly sloping beaches, to storms on steep beaches. • A river jetty increases seasonal response of OPE-behaving bars, giving episodic NOM. • Numerical simulations highlight the role of wave direction at bounded beaches. [ABSTRACT FROM AUTHOR]