Beach Monitoring and Morphological Response in the Presence of Coastal Defense Strategies at Riccione (Italy)

Abstract

The coastal area at Riccione, in the southern Emilia-Romagna littoral region, is exposed to erosive processes, which are expected to be enhanced by climate change. The beach, mostly composed of fine sand, is maintained through various defense strategies, including frequent nourishment interventions for balancing the sediment deficit and other experimental solutions for reducing coastal erosion. Artificial reshaping of the beach and “common practices” in the sediment management redefine the beach morphology and the sediment redistribution almost continuously. These activities overlap each other and with the coastal dynamics, and this makes it very difficult to evaluate their effectiveness, as well as the role of natural processes on the beach morphological evolution. Topo-bathymetric and sedimentological monitoring of the beach has been carried out on a regular basis since 2000 by the Regional Agency for Prevention, Environment and Energy of Emilia-Romagna (Arpae). Further monitoring of the emerged and submerged beach has been carried out in 2019–2021 in the framework of the research project STIMARE, focusing on innovative strategies for coastal monitoring in relation with erosion risk. The aim of this study is to assess the coastal behavior at the interannual/seasonal scale in the southern coastal stretch of Riccione, where the adopted coastal defense strategies and management actions mostly control the morphological variations in the emerged and submerged beach besides the wave and current regime. The topo-bathymetric variations and erosion/accretion patterns provided by multitemporal monitoring have been related to natural processes and to anthropogenic activities. The morphological variations have been also assessed in volumetric terms in the different subzones of the beach, with the aim of better understanding the onshore/offshore sediment exchange in relation with nourishments and in the presence of protection structures. The effectiveness of the adopted interventions to combat erosion, and to cope with future climate change-related impacts, appears not fully successful in the presence of an overall sediment deficit at the coast. This demonstrates the need for repeated monitoring of the emerged and submerged beach in such a critical setting.

Repeated (4D) Marine Geophysical Surveys as a Tool for Studying the Coastal Environment and Ground-Truthing Remote-Sensing Observations and Modeling

“…The data collected in the study area during the one-year experiment suggested that 4D (repeated) surveys are feasible using the employed technologies, since consistent differential bathymetric and reflectivity models of the seafloor were obtained. Morphological changes, not limited to the subaerial beach but extending to the nearshore area, are more significant for evaluating the state and evolution of a coastal area than the shoreline behavior alone, which is very variable and often affected by anthropic bias [38,39]. Comparisons with independent hydrodynamic modeling also suggested an interesting fit between predicted and observed erosional/depositional patterns.…”

Use of a Raspberry-Pi Video Camera for Coastal Flooding Vulnerability Assessment: The Case of Riccione (Italy)

“…In the frame of the STIMARE project (STrategie Innovative, Monitoraggio ed Analisi del Rischio Erosione, www.progettostimare.it, accessed on 12 January 2022) [37], several surveys were performed between 2019 and 2021 to employ and compare different monitoring techniques. One of the goals of the project was to evaluate the morphological response of the studied beach to annual and seasonal wave regimes and to different coastal defense strategies [38].…”

“…Surveys were carried out every 6 months on the emerged and submerged beach during the project duration (see [38] for details); the date and techniques of the different surveys are reported in Table 1. In the present work, only data from the emerged and intertidal beaches are shown.…”

Microwave Drying Method before Sieving to Obtain Accuracy of Sand Size Parameters

“…This technique may also be used to forecast how long beach sand will last and how it will respond to storms [8,[12][13][14][15][16]. Measurements of the main sand size characteristics, primarily the median grain size (D 50 ) and the sorting (distribution of sizes around the average, σ), are part of the analysis conducted to investigate coastal processes [17][18][19][20].…”