Coastal erosion in temperate barriers: an anthropized sandy beach in Buenos Aires, Argentina

Abstract

Coastal erosion is a common issue in urbanized areas located on sandy barriers in Latin America, making them highly vulnerable to both natural and human induced disasters. This pose a significant threat to the long-term sustainability of these coastal systems. The main objective of this study was to evaluate the medium-term shoreline evolution of a highly-anthropized beach sector located within a coastal barrier system of Buenos Aires, Argentina. For this purpose, a geospatial analysis based on aerial imagery and high-resolution satellite data was conducted for the 1965–2021 period. Additionally, the study aimed to identify critical erosive sectors and to provide estimations for the near-future shoreline evolution of these beaches. The results showed contrasting patterns, with sectors presenting shoreline retreat rates up to 0.7 m/yr while others demonstrated accretion rates exceeding 0.6 m/yr. Despite these along-shore variations in erosion/accretion balances, more than 70% of the shoreline presented an erosional trend for the studied period. This led to the identification of an erosional hot spot covering 30% of the urbanized waterfront. Furthermore, the 2030 forecast suggests that a highly urbanized beach sector could suffer a shoreline retreat of about 20 m. These results could be directly linked to the historical land use/land cover changes, mainly related to dune stabilization processes and to the implantation of urban surfaces. At this point, erosive patterns could be mainly caused by local cross-shore imbalances due to these anthropogenic disturbances. It is expected that the results of the present study will serve as a basis for coastal management policies, and the proposed method will be a useful tool for assessing coastal erosion hazard.