UAV-based high-resolution analysis of seasonal morphodynamic response of a beach–dune system under contrasting oceanographic conditions, Mar del Plata (Argentina)

This study aims to evaluate the dynamics of a semi-hanging beach–dune system in an open sandy beach during winter and summer 2021–2022, using UAV-based Structure-from-Motion (SfM) and Multi-View Stereo (MVS) surveys. Morphometric and morphodynamic parameters were extracted from DEM-derived cross-shore profiles and 3D clouds were compared. Oceanographic forcings were analysed to identify storm events and dune impact hours, while sediment volume balance was quantified. Results highlighted the critical role of winter storms (May–September), where five extreme events triggered foredune erosion of 8600 m3, with an average dune toe retreat of 3.5 m. Sediments were redistributed on the beach, accumulating 4100 m3, favouring a storm berms and cusp formations, completely eroded in summer. Over the annual period, the foredune was unable to recover from the storm-induced sediment deficit. Post-storm alongshore variability was mainly controlled by antecedent beach and dune slopes, dune toe height, and the cumulative duration of impact hours. Overall, the results indicate a clear sedimentary imbalance in the system, characterized by high vulnerability to severe events and low resilience. This study contributes new insight into the morphodynamic behaviour and resilience of semi-hanging beach–dune on the Buenos Aires coast and demonstrates the effectiveness of UAV-based SfM-MVS monitoring in capturing coastal morphodynamics.