Monitoring beach erosion along the Italian coast: the case of Molise regional coast (Central Adriatic)

Abstract

Coastal areas characterized by sandy shorelines are among the most dynamic environments and subject to deep and rapid changes over time under the influence of natural and anthropic factors. To deepen the understanding of the potential future development of a sandy coast, therefore better outline sustainable coastal management measures, the reconstruction of its geomorphological and anthropogenic evolution, current state and possible future trends are of crucial importance. For this purpose, we have examined the coast of Molise region in Italy, which is prevailingly made of sandy shorelines and characterized by widespread anthropogenic impact mostly due to tourism and the presence of hard defense structures. The Molise coast has experienced intense erosion since the 1950s that caused a land loss of nearly 1 km2 and primarily struck the coastal sectors including major river mouths (Trigno and Biferno) where shorelines retreated up to 400 m during approximately the last 65 years [1]. To counteract ongoing shoreline retreat, hard defense structures, mainly adherent and detached breakwaters, and groins, were built over time. Nevertheless, erosion partly further accelerated it pace over the last decades, and involved increasingly coastal stretches located south of the Trigno and Biferno mouth sectors [1, 2]. Concerning furthermore the susceptibility to coastal flooding, first evaluations based on sea-level projection SSP5-8.5 performed for the southern Molise coast have highlighted that approximately 1.32 km2 (5%) of it could be subject in the near future (year 2050) to permanent flooding [2]. Since 2016, remote sensing activities and modellings are integrated by periodical, partial annual monitoring campaigns. Field measurements mostly concern shoreline positions, sedimentary and topographical-morphological features of dune fronts, backshore/foreshore zones, and morpho-bathymetric features of the beach extending up to the closing depth, allowing their large-scale documentation and data update. Especially recent drone survey campaigns (2019-2021) along strategic/critical coast stretches [3] allowed for the rapid creation of digital terrain models, and the assessment of recent morpho-topographic beach and shoreline changes. The set of validated field survey methodologies, along with the campaigns planned for the near future, represent the monitoring plan outlined for the Molise coast for defining future action strategies aimed at supporting its sustainable development and mitigating the effects of ongoing climate changes.   Key words Beach erosion, coastal monitoring, climate change [1] Rosskopf C.M., Di Paola G., Atkinson D.E., Rodríguez G., Walker I.J. (2018) Recent shoreline evolution and beach erosion along the central Adriatic coast of Italy: The case of Molise region. Journal of Coastal Conservation, 22, 879–895. [2] Di Paola G., Valente E., Caporizzo C., Cozzolino M., Rosskopf C.M. (2023) Holocene to near-future evolution of the southern Molise coast (Central Adriatic, Italy) under the influence of natural and anthropogenic controls, Journal of Maps, 19:1, 2243973. [3] Di Paola G., Minervino Amodio A., Dilauro G, Rodriguez G., Rosskopf C.M. (2022) Shoreline Evolution and Erosion Vulnerability Assessment along the Central Adriatic Coast with the Contribution of UAV Beach Monitoring. Geosciences, 12, 353.