Experimental determination of the friction coefficient for estimating sea storm induced megaboulders movements.

The presence of numerous boulders on rocky coast is linked to phenomena of detachment and deposit due to the occur-rence of sea storms. Currently, several hydrodynamic equations are known in the bibliography to estimate the wave height able to dis-place them, applying geometric parameters and hydrodynamic coefficients. A new methodological approach intends to consider the minimum energy required for the linear movement of a boulder along a weakly sloping rocky surface as a function of the friction coefficient

Terrestrial Laser Scanner techniques in the assessment of tsunami impact on the Maddalena peninsula (south-eastern Sicily, Italy)

The coastline of the Maddalena peninsula (south-eastern Sicily, Italy) is characterised by the occurrence of a boulder field associated to an extended soil stripping area and by a gravel/sandy berm. The accumulation of the boulders has been mostly correlated to the impact of the December 28, 1908 tsunami wave. The use of Terrestrial Laser Scanner survey techniques, associated to Differential Global Position System determinations, permits to obtain new data for the assessment of tsunami impact on this coastal area. The computing of the surveyed data using the most recent equations is a useful tool in order to estimate the theoretic inundation limit and to reconstruct its variability in function of the boulders size and of the coastal topography. Moreover, the entire new data set allows to confirm that the hypothesis of the tsunami impact is the most reasonable to explain the occurrence of boulders weighing up to 50 tons on the Maddalena peninsula

Energy balance to transport massive boulders on rocky coast area.

Along the Italian rocky coasts it’s possible to recognize deposits made up mainly of boulders, isolated or accumulated in fields and berms, at elevations and distances variables from the shoreline. These singular geomorphological evidences are connected to extreme marine events such as storm surge that are frequents on rocky coast of Apulia region. During a storm event, a high energy flux is produced, to allow the transport of boulders along the coast in different scenarios, like subaerial, submerged and joint bounded. Evaluating energy flux needed to move boulders respect the energy flux deriving from a storm, it’s possible quantify the number of waves needed to move the boulders. Here an example of boulders transported on rocky coast is given by Torre dell’Ovo area, 45 kilometers south-east of Taranto

Il WebGis sugli tsunami: un utile strumento di consultazione

The need to cr eate an integrated maritime policy underline by the European Commission has been taken on board in Italy through the achievement of the Program RITMA RE, the Italian Researc h for the Sea. Concerning of this project, has been drafted a list of scientific references about tsunami events that occ urr ed in Italy. The articles have been collected through the consultation of digital libraries; arr anged by area of study and inserted into a geographic database. This geo-database has been used for GIS implementation, subsequently published on the web, via map serv er, on the site of the program Ritmare (www.ritmare.it)

Comparing impact effects of common storms and Medicanes along the coast of south-eastern Sicily

The coastal vulnerability along the Mediterranean coasts is increasing, especially in response to the occurrence of tropical-like cyclones, known as Medicanes, which have become more intense than in the past. A peculiar case was the impact of Medicane Zorbas in September 2018 along the coasts of south-eastern Sicily, where it caused inland flooding and damages to the socio-economic activities. Here, Zorbas effects are reconstructed through post-event geomorphological surveys, interviews with direct witness and analyses of video recorded by surveillance systems or found in social media. These data allowed us to assess the flooding extent on seven coastal sectors located between Thapsos Peninsula and Marzamemi. Flooding caused by Zorbas appears to be greater than those produced by the main seasonal storms affecting the areas from 2015 to 2019; nevertheless, it is comparable with the flooding generated by Medicane Qendresa that impacted south-eastern Sicily in 2014. Wave propagation and extreme water level modelling, performed for the main storm events that occurred in the area since 2005, and analyses of data recorded by tide gauges of Catania, Porto Palo di Capo Passero and Malta since 2008, showed that Medicanes generate greater flooding than seasonal storms because they can induce higher and longer surge along the coastline. Collected data indicated that the surge generated by Zorbas reached a maximum value between about 0.8 m and 1.2 m above mean sea level (msl) along the coast of south-eastern Sicily. Results highlighted the need to better evaluate the coastal hazard related to the propagation of Medicanes, especially in the context of future climate change when these events will probably be characterized by longer duration and greater intensity than at the present

Geomorphological Signature of Late Pleistocene Sea Level Oscillations in Torre Guaceto Marine Protected Area (Adriatic Sea, SE Italy)

Morphostratigraphy is a useful tool to reconstruct the sequence of processes responsible for shaping the landscape. In marine and coastal areas, where landforms are only seldom directly recognizable given the difficulty to have eyewitness of sea-floor features, it is possible to correlate geomorphological data derived from indirect surveys (marine geophysics and remote sensing) with data obtained from direct ones performed on-land or by scuba divers. In this paper, remote sensing techniques and spectral images allowed high-resolution reconstruction of both morpho-topography and morpho-bathymetry of the Torre Guaceto Marine Protected Area (Italy). These data were used to infer the sequence of climatic phases and processes responsible for coastal and marine landscape shaping. Our data show a number of relict submerged surfaces corresponding to distinct phases of erosional/depositional processes triggered by the late-Quaternary interglacial–glacial cycles. In particular, we observed the presence of submerged marine terraces, likely formed during MIS 5–MIS 3 relative highstand phases. These geomorphic features, found at depths of ~26–30, ~34–38, and ~45–56 m, represent important evidence of past sea-level variations

Sea-Level Rise and Shoreline Changes Along an Open Sandy Coast: Case Study of Gulf of Taranto, Italy

International audienceThe dynamics of the sandy coast between Castellaneta and Taranto (Southern Italy) has been influenced by many natural and anthropogenic factors, resulting in significant changes in the coastal system over the last century. The interactions between vertical components of sea-level changes and horizontal components of the sedimentary budget, in combination with anthropogenic impact, have resulted in different erosion and accretion phases in the past years. Local isostatic, eustatic, and vertical tectonic movements, together with sedimentary budget changes, must be considered in order to predict the shoreline evolution and future marine submersion. In this study, all morpho-topographic data available for the Gulf of Taranto, in combination with Vertical Land Movements and sea-level rise trends, were considered by assessing the local evolution of the coastal trend as well as the future marine submersion. Based on the predicted spatial and temporal coastal changes, a new predictive model of submersion was developed to support coastal management in sea-level rise conditions over the next decades. After that, a multi-temporal mathematical model of coastal submersion was implemented in a Matlab environment. Finally, the effects of the relative sea-level rise on the coastal surface prone to submersion, according to the Intergovernmental Panel on Climate Change Assessment Reports (AR) 5 Representative Concentration Pathways (RCP) 2.6 and RCP 8.5 scenarios, were evaluated up to 2100

The First Video Witness of Coastal Boulder Displacements Recorded during the Impact of Medicane “Zorbas” on Southeastern Sicily

Over the last few years, several authors have presented contrasting models to describe the response of boulders to extreme waves, but the absence of direct observation of movements has hindered the evaluation of these models. The recent development of online video-sharing platforms in coastal settings has provided the opportunity to monitor the evolution of rocky coastlines during storm events. In September 2018, a surveillance camera of the Marine Protected Area of Plemmirio recorded the movement of several boulders along the coast of Maddalena Peninsula (Siracusa, Southeastern Sicily) during the landfall of the Mediterranean tropical-like cyclone (Medicane) Zorbas. Unmanned autonomous vehicle (UAV) photogrammetric and terrestrial laser scanner (TLS) surveys were performed to reconstruct immersive virtual scenarios to geometrically analyze the boulder displacements recorded in the video. Analyses highlighted that the displacements occurred when the boulders were submerged as a result of the impact of multiple small waves rather than due to a single large wave. Comparison between flow velocities obtained by videos and calculated through relationships showed a strong overestimation of the models, suggesting that values of flow density and lift coefficient used in literature are underestimated