Assessing the risk of coastal oil strandings in the Brazilian equatorial margin: A numerical modeling approach

The Brazilian Equatorial Margin (BEM) holds major ecological, climatic, and socio-economic importance and is emerging as a new frontier for offshore oil exploration in Brazil. This study aims to identify and characterize the preferential surface transport pathways of oil spills from four potential spill points located in the Potiguar (SPO), Barreirinhas (SBAR), Pará-Maranhão (SPAMA), and Foz do Amazonas (SFZA) basins. Lagrangian simulations were conducted with the OpenDrift model using surface velocity fields from the Surface Merged Ocean Current (SMOC) model. Validation confirms that SMOC accurately reproduces the spatio-temporal variability of surface currents, while OpenDrift proves reliable for simulating oil transport and dispersion. Results indicate that most of the BEM could be affected by potential spills, with preferential pathways and coastal stranding zones varying according to spill location. Spills from SPO and SBAR (points 1 and 2) show the highest impacts, with over 80 % intrusion on the continental shelf and more than 30 % coastal stranding, whereas SFZA (point 4) shows no intrusion or stranding. These pathways are modulated by trade wind variability and mesoscale activity of the North Brazil Current (NBC). Higher intrusion and stranding generally occur in summer and spring, though without a strong seasonal trend. The findings highlight the importance of identifying oil transport pathways to support region-specific contingency planning, as elevated stranding risks threaten sensitive coastal ecosystems and local livelihoods, underscoring the need to integrate operational oceanographic modeling into coastal management.