Italian National Agency for New Technologies, Energy and Sustainable Economic Development
Environment: Innovative model to study coastal erosion
A research team from ENEA, Cnr, and the Universities of Cagliari and Sassari has developed an innovative model to study marine circulation, particularly in the Mediterranean, and identified the causes of coastal erosion and the evolution of beaches, including that of Stintino in Sardinia, as reported by a study published in a special issue of the international journal Geological Society Publications.
The study focused on the Mediterranean, a region representative of what is happening on a global scale, where climate change impacts with amplified effects.
The study investigated specifically the Strait of Asinelli -which separates the Sardinian sea from the Gulf of Asinara- whose seabed is characterized by a complex and intertwined distribution of rocks, sand, Posidonia oceanica meadows and changing submarines dune systems.
The study of the circulation of currents revealed the cause of the erosion of the beach of Stintino (La Pelosa), in front of the strait, increasingly affected by climate change and, in the last 30 years, by a growing erosion affecting its extension and shape, which vary according to the rise of the sea level, the underwater meadow of Posidonia and wind regimes. Wind causes beach erosion by displacing grains westwards, towards a gully which causes them to deposit at a depth of 15-30 m, from where they are then unable to go back up again. Thanks to this methodological approach, the researchers retraced the evolutionary history of this very peculiar environment and will be able to contribute to the environmental redevelopment of the Stintino beach-dune system.
The model’s peculiarity is that it combines wind and wave motion analysis, underwater surveys, sensors, aerial photo interpretations, but also seabed scans with geophysical prospecting (such as Side Scan Sonar, Sub Bottom Profiler and Multi Beam ) and implementation of high resolution numerical models. In addition to understanding the behavior of marine straits, actual 'waterways' that connect different basins, the model allows to study the circulation of sediments in conditions of low tidal oscillations in which wind patterns -variable due to climate change affecting them- are the main cause of environmental dynamics.
"Understanding the straits and connections among basins is fundamental for current sedimentary depositional systems, for regional geological reconstructions and for large-scale and long-term tectonic and palaeogeographic evolution", said Stefano Andreucci of the University of Cagliari, first author of the work.
"Comprehending the processes affecting the strait between Sardinia and the island of Asinara is not only important for the interest and economic value of the Stintino beach, but it is also useful for completing a Geological Sheet of the area. To this aim, in the last twenty years our university has invested considerable human and economic resources to acquire data through several research projects which acquired a great deal of information on the area", pointed out Vincenzo Pascucci of the University of Sassari.
“Simulation of the circulation in such complex environments is always a very ambitious and pioneer work, considering the morphological complexity and variability of waves and currents forming in these highly dynamic areas, very sensitive to climate change. The scientific community has long been engaged in sea level observations and the study of the lateral boundaries of basins; understanding the complex hydraulic dynamics across the Mediterranean straits is a frontier and extremely complex line of research", said Andrea Cucco of the CNR-IAS.
“The latest 2021 IPCC report shows that average sea level rise projections are not accurate enough for marginal basins like the Mediterranean, which require the development of specific models. ENEA's MED16 numerical oceanographic model fills this gap by focusing precisely on high-resolution simulations around the Dardanelles, Bosphorus and Gibraltar. ENEA models have also recently been used in a joint ENEA - MeteoFrance project to understand the complex water exchange mechanisms that take place in the Strait of Gibraltar between the Mediterranean and the Atlantic Ocean. In this study, thanks to a twenty-year collaboration with Sardinian universities, a general conceptual model was created based on current data, to be replicated in other contexts, which helps understand what the rocks formed in similar coastal environments and in other straits can tell us”, explained Sergio Cappucci of ENEA.
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