Rockfall hazard mitigation in coastal environments using dune protection: A nature-based solution case on Barinatxe beach (Basque Coast, northern Spain)

Across the world, coastal environments of great landscape, recreational and environmental value are coming under increasing pressure. Within such environments, cliffs are particularly characteristic and unique elements, in which processes of instability develop. Their management requires a transdisciplinary approach ensuring protection of the natural condition of the environment, while at the same time allowing for their continued use and enjoyment. In the case of Barinatxe (Basque Coast), the beach has evolved into a system of foredunes, flanked by cliffs with frequent rockfall processes. This research analyzes the effect of coastal dunes as an element of natural protection. To this end, based on a Digital Terrain Model developed by Terrestrial Laser Scanning (TLS) and in situ geological characterization, 3D modeling has been used to analyze rockfall trajectories and evaluate their runout and energy. These models confirm the protective role of coastal dunes, which act as efficient natural barriers against rock blocks that become detached from cliffs. This is particularly important in areas where the use of tools based on Nature-Based Solutions (NBSs) guidelines is recommended.