Medium-term dynamics of a middle Adriatic barred beach

Abstract

Abstract. 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.

Coastline evolution based on statistical analysis and modeling

“…This sea level variation could justify the slight accretion characterizing both the northern and southern areas in 2011-2013, as well as the analogous shoreline advancement observed in the other two investigated cells (as shown in the following). For the same temporal range, a similar tendency also characterized the beach of Senigallia, located in the central Adriatic Sea, north of the investigated site, where a general retreat was recorded (Postacchini et al, 2017).…”

“…Shoreline evolution, characterized by erosion and deposition areas, has consequences on socioeconomic activities and ecosystems. Therefore their evolution and understanding represent a challenge to coastal communities, coastal infrastructures and adjacent estuarine environments (Cutter et al, 2008;Torresan et al, 2012;Mossa, 2014, 2016;Samaras et al, 2016;De Padova et al, 2017;Armenio et al, 2017aArmenio et al, , 2018.…”

Coastal Sensitivity/Vulnerability Characterization and Adaptation Strategies: A Review

“…In turn, bars represent a preferential point of breaking-induced energy dissipation during energetic events such as sea storms, thus representing a form of beach protection that strongly affects beach erosion and shoreline motion. Furthermore, the dynamic equilibrium existing in the nearshore region is such that the wave features (in particular the wave height) strongly affect the shoreward/seaward bar migration [74][75][76]. The wave height is thus included in CVI applications as an indicator of the wave energy, although there is not a sole way to define such variable.…”

Statistical Deviations in Shoreline Detection Obtained with Direct and Remote Observations

“…The technology is relatively low-cost, but the main issue is the processing method, especially the image rectification process, considering that the imagery is strongly oblique and relies on a number of GCPs (Ground Control Points) for finding the best geometry solutions. This technique has been successfully applied for both shoreline monitoring [29,30], rip current measurement [14] and morphodynamics classification of sandy beach [31,32].…”