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This paper investigates the dynamics of the cross-shore extensions of banquettes, a sedimentary structure mostly made by rests of Posidonia oceanica (L.) Delile, in a sandy urban beach located in the Gulf of Cagliari, Italy, western Mediterranean. A video monitoring station was installed above the promontory south of the beach. We analysed a four-year image database and related these dynamics to wave and wind parameters (obtained from the Copernicus and ERA5 databases) from September 2016 to September 2020. Our results showed that banquette deposition occurred in concomitance with the presence of leaf litter in the surf zone associated with mild storm events. Erosion of the banquettes occurred during more intense storms. When leaf litter was not present in the surf zone, banquettes were not deposited even with mild storms. Wind can influence the banquette dynamics: under certain conditions of speed intensity, the banquettes may be removed offshore, supplying litter in the surf zone, or they may be covered by sediment. The permanence of the banquettes on the beaches also depended on their composition: when the banquettes were intertwined with reeds, their removal by the waves did not occur even during intense storms, and this sedimentary structure can protect the beach from flooding. [ABSTRACT FROM AUTHOR]

Using a comprehensive cartographic product, this paper aims to illustrate the evolution of the urban geomorphological setting of the urban coastal belt of Cagliari (southern Sardinia, Italy, western Mediterranean Sea). The geomorphological map (1:14,000) presented herein summarizes different data (e.g. urban development, anthropogenic features, geomorphological elements, recent deposits, sedimentological distribution, hydrodynamics and ecological components) acquired through an integrated sea-land approach and a multidisciplinary-multitemporal investigation. The main significant environmental changes are linked to urbanization, the development of port infrastructures (embankments along the shoreline and the construction of the canal harbour), remediation work and filling activities, and the hardening of dune and beach systems and cliffs. These man-made interventions have increased the vulnerability of the shore zones to flood hazards and risks, which are linked to sea-level rises and global warming. [ABSTRACT FROM AUTHOR]

This paper presents a map describing the main geomorphological and sedimentological features, hydrodynamics, benthic habitat distributions and human impact on the coastal and marine areas of the Archipelago of La Maddalena (NE Sardinia, western Mediterranean). This cartography is based on an interdisciplinary sea-land approach, with the aim being to support sustainable and successful beach management in the face of a changing climate and environment, thereby contributing to the achievement of the Agenda 2030 Sustainable Development Goals (13, 14 and 15). In the Main Map (1:14,000 scale), the static and dynamic features of the beach systems and adjacent inner shelf are divided into thematic sections that include the geomorphological elements, hydrodynamics, sedimentological distributions, benthic habitat (mainly Posidonia oceanica meadow) and anthropogenic impacts. The map establishes a fundamental, multidisciplinary benchmark that is able to provide substantial scientific support to policymakers in relation to future vulnerability-assessment activities and the definition of land-management strategies. [ABSTRACT FROM AUTHOR]

Trogu, D.; Buosi, C.; Ruju, A.; Porta, M.; Ibba, A., and De Muro, S., 2020. What happens to a Mediterranean microtidal wave-dominated beach during significant storm events? The morphological response of a natural Sardinian beach (western Mediterranean). In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 695-700. Coconut Creek (Florida), ISSN 0749-0208. The short-term effects of storm events on the coastline morphology of natural, microtidal, wave dominated beaches located in the western Mediterranean are still poorly documented. Since one of the most visible consequences of a warming climate is an increase in the intensity and frequency of extreme weather conditions, it appears important to know the response of natural and urban beaches to these storm events. The spatial shoreline variability of a natural Sardinian beach was assessed in our study, based on video camera monitoring data from August 2013 to August 2015 along a 0.3 km stretch of sandy beach. This methodology has been applied in the SW coastal sector of Sardinia where severe storm events mainly related to southwesterly winds (about 50 km/h on average) can induce important morphological changes. These include shoreline retreat/progradation, erosion, beach rotation, reconfiguration of nearshore bars and the deposition of significant seagrass beach-cast litters. Our study showed an erosion and a consequent accretion of the studied beach of about 20 m in two days after the event (SW wind and waves) as a result of the deposition of the Posidonia oceanica beach-cast litter. This morphological response induced by storm events is crucial for coastal managers to plan beach management (for example beach cleaning practice), to prevent coastal risk and to understand the importance of seagrass berm deposition in the formation of natural Mediterranean beaches. [ABSTRACT FROM AUTHOR]

Urban Mediterranean beaches are often characterized by a fragile and unstable equilibrium that can be easily altered by ongoing climate change and by the increase in human pressure. This may pose serious threats to the survival of beach systems that cannot accommodate these modifications. In this paper, the spatio-temporal shift of the shoreline was investigated along two urban beaches in the Gulf of Cagliari (Poetto and Giorgino; southern Sardinia, western Mediterranean Sea) across a time frame of 62 years (1954–2016). The Digital Shoreline Analysis System (DSAS) ArcGIS™ extension was used to extract different statistical parameters which allowed us to quantify the erosion and accretion rates. These data were further examined in relation to a number of anthropic and natural forcings in order to disentangle the factors controlling shoreline evolution. Eight sectors with interchanging net erosive and accretion trends were identified along the Poetto and Giorgino beaches. In six decades, some sectors of the two study sites appeared to have undergone great shoreline modification as a result of the intense anthropogenic activities impacting these coastal areas. The westernmost portions of both beaches were found to be the most vulnerable to erosion processes; such conditions were likely controlled by the interplaying of local hydrodynamics and by the intense coastal development which affected these sectors. The highest retreat rates (mean end point rate (EPR) = −0.51/year) were recorded in the western limit of Giorgino beach. Along the western limit of Poetto beach, EPR erosion rates (mean EPR = −2.92/year) considerably increased in the years after the artificial beach nourishment carried out in 2002, suggesting that the majority of the nourished material was lost offshore or partly redistributed along the beach. Coastal structures, urban development, river catchment modification, industrial and port activities, beach cleaning and touristic and recreational activities have been identified as the ongoing causes of coastal alteration. If these factors remain constant, under projected climate change scenarios, these beaches are at risk of further increased flooding and erosion. In this context, the application of DSAS appeared as an essential tool, supporting a monitoring system able to provide understanding and, potentially, predictions of the short- to long-term evolution of these beach systems. [ABSTRACT FROM AUTHOR]

This paper reports a scientific inquiry carried out within the management process of an exceptional accumulation of reeds and seagrasses that took place in December 2019 on Poetto beach (Cagliari, southern Sardinia, western Mediterranean). The magnitude of the event raised concern within the local community and tourism service providers especially for the compromised beach accessibility caused by this large amount of biomass. The scientific inquiry is carried out in support of coastal management, to assess the berm processes before the removal of the reed wracks decided by the local municipality. By means of a numerical approach, this work devotes special attention to the runup induced by storms in the presence of reed and seagrass deposits on a low-lying backshore. Field surveys reported relatively large conductivity parameters in the presence on reed and seagrass deposits. The numerical approach shows that the increased beach permeability can eventually mitigate coastal flooding induced by storms. These results highlight the ecosystem services provided by reed and seagrass wracks together with the implications for coastal protection and management. • Large permeability values were measured in areas with seagrass and reed deposits. • A numerical approach assesses runup and infiltration processes on a sandy beach. • Reed and seagrass wracks can mitigate flooding by increasing beach permeability. [ABSTRACT FROM AUTHOR]