BERMA – Beach Erosion Mechanism Analysis: Studio della dinamica sedimentaria lungo le spiagge pugliesi con approcci multidisciplinari

This study focuses on the analysis of sandy beaches by integrating sedimentological, geomorphological, and geophysical investigations. The beach represents a complex environment where different natural processes simultaneously interact with human activities, leading to the need of gathering different methodologies of the Earth Sciences to study its evolution operating at a variety of temporal and spatial scales. In particular, the Apulia Region (Southern Italy) is characterised by 650 km of sandy littoral sectors where the growth of the urbanization, the concentration of the economic and tourist facilities in the last decades, have led these coastal areas to be affected by erosional processes. The aim of this research is to build a standard procedure to understand and predict the morpho-sedimentary processes driving the dynamics of sandy beaches. Such approach has been achieved by analysing the textural and compositional characteristics of the sands and quantifying the volumes involved in the coastal dynamics over three years. The study areas include two Apulian sandy beaches (Torre Guaceto and Le Dune beach) which are representative of a large sector of the central/northern Mediterranean Sea involving part of southern Adriatic Sea and of northern Ionian Sea. Torre Guaceto beach is a 1 km wide littoral stretch located on the Adriatic Sea characterised by a relatively slight human impact and a significant availability of previous data that allows to observe the natural ii dynamic effects on the health state of the beach. Beach sediments range between coarse and fine sands and they include both siliciclastic and carbonate grains. Le Dune beach is located along the Ionian Seaside and it has a maximum width of 800 m. Beach sediments range from very coarse to medium-fine sands and they are mainly made up of bioclast fragments. Both study areas are part of marine protected reserves which includes 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia oceanica meadows. Sedimentological and ecological investigations allowed describing the textural and compositional characteristics of the beach sands by interpreting their sand provenance and the physical/biological interactions within the beach. Moreover, the relationships between the main statistical parameters have been used to establish the seasonal erosive or stable-prograding tendency of the beach. The topographic surveys carried out with a Terrestrial Laser Scanner and an Optical Total Station, aimed to quantify the variations of sediment volume of the beach, whereas the Delft3d software was applied to analyse the effects of the dominant wave motion on the sedimentary dynamics. Lastly, the geophysical techniques which included Sub bottom profiler procedures, ground penetrating radar investigation and resistivity models enabled to calculate the sand sediment thickness above the bedrock.