Seasonal morphodynamic changes of an estuarine coast assessed with SfM-MVS and wave climate drivers (Río de la Plata, Argentina)

Coastal erosion is a major challenge along the eastern Argentine coast, driven by natural dynamics—intensified by climate change—and anthropogenic impacts from inadequate management. The littoral zone of the Río de la Plata estuary has experienced significant erosion in recent decades, threatening infrastructure and ecosystems. This study examines El Picaflor beach, documenting seasonal and interannual morphological changes through high-resolution monitoring. Semi-annual surveys were conducted from February 2020 to April 2024 using UAV imagery and Structure from Motion–Multi-View Stereo (SfM-MVS) photogrammetry, complemented with estuarine wave climate analysis.Results reveal a net erosive trend across the entire beach, with strong spatial variability. The northern sector exhibited the most severe erosion, including beach profile lowering, escarpment retreat, and exposure of underlying clay units. These patterns are closely linked to beach geometry, orientation, and local wave climate. Seasonal patterns reveal that summer months present stronger erosive dynamics, with net erosion in the northern and central sectors and localized deposition in the south. In contrast, winter periods show only mild erosion, without significant escarpment retreat.Wave climate analysis highlights strong seasonality, with minimum values in June and maximum values in October-November. These values are more typical of outer estuarine conditions. Together with evidence of increasing wind-driven waves in the Southwestern Atlantic over recent decades, this suggests enhanced erosive forcing in the study area. Current coastal protection measures have proven ineffective. Therefore, sustainable strategies such as semi-rigid structures and restoration of intertidal vegetation are proposed as cost-effective alternatives to mitigate future erosion.