Density of tourists and morphology of shifting dunes

The joint use of photogrammetric data obtained from aerial surveys with the drone and direct observations in the field has made possible to interpret the structural characteristics of the dune systems in relation to the anthropogenic disturbance.

For the project areas at the Cavallino Peninsula, Laguna del Mort and pine forests of Eraclea, Laguna di Caorle and Foce del Tagliamento, the Cà Foscari University and EPC srl, Life Redune project partners, evaluated whether and how the shifting dunes height varied with the as the changes of the density of tourists on the beach. In particular, during the summer seasons 2020 and 2021 – therefore during the season of maximum tourist turnout – the spatial limits of the presence of tourists on the beach were defined starting from the main accesses, quantifying the density on 100 m2 at increasing distances from the accesses. The tourist density data was then compared with the shifting dunes variation of height.

In general, a clear correspondence emerged between the density of tourists and the height of the shifting dunes: areas with high density show a lower average height of the shifting dunes than areas that are sparsely frequented. In unsurveilled areas, a high density of tourists can coincide with a greater trampling disturbance borne by the dune system. Trampling, in turn, by damaging the plant organisms and the dune profile itself, causes a reduction in the height of the shfting dunes, with a consequent loss of structure and functionality of the entire dune system.

Furthermore, from the surveys carried out in the field, it emerged that tourists tend to occupy the portion of the beach in the immediate vicinity of the main access, rarely spreading beyond 100 m from it. This result highlights how a distance between consecutive accesses of at least 250 m can represent a limit value that increases the possibility of preserving the structural and functional integrity of stretches of coastal dune systems.