Numerical Modelling of the FSO Safer Oil Spill Scenario in the Southern Red Sea

Source abstract

Introduction . This study is devoted to mathematical modeling of accidental oil spill scenarios in the Red Sea in the vicinity of the floating storage and offloading unit FSO Safer off the coast of Yemen. Predictive trajectories of oil-slick drift were constructed under the combined effects of advection, diffusion, evaporation, dissolution, and biodegradation. The modelling results made it possible to identify spatiotemporal patterns of slick transformation, determine the areas of greatest environmental risk along the Yemeni coast, and assess potential damage to marine ecosystems and the region’s socioeconomic infrastructure. Materials and Methods . A three-dimensional numerical oil-spill model was developed to predict oil transport and weathering during the first 72 h, which are most critical for mounting an emergency response. The numerical model uses surface currents and temperature from the HYCOM GOFS 3.1 global analysis and winds from the ERA5 reanalysis. Oil dynamics were simulated accounting for the multifraction composition of the oil, the mesoscale character of the currents, physicochemical weathering processes (evaporation and dissolution), and biodegradation kinetics coupled with microbial population dynamics. Results . The results show a slow northeastward displacement of the slick at a velocity of approximately 0.03 m/s (6.5 km over 72 h), with landfall near Ras Isa during the first day. Mass loss over 72 h is 23.4%, of which 96.7% is due to evaporation and 3.3% is due to dissolution, whereas the contribution of biodegradation at realistic microbial biomass levels does not exceed 0.1% over this time horizon. In addition, a regime of persistent northward transport was considered, selected from a threeyear series of current and wind data for 2023–2025. From January 29 to February 1, 2023, the slick travels approximately 100 km northward along the Yemeni coast to the Kamaran Islands in three days, while mass loss increases to 32%. Discussion . Accurate drift forecasting requires up-to-date hydrometeorological data for the scenario date because the trajectory and displacement distance are determined by the current and wind fields. Satellite radar monitoring data are used as initial conditions. Conclusion. A reproducible predictive oil-spill model based on open data was developed for operational monitoring and environmental risk assessment in the southern Red Sea. The results provide a scientific basis for the urgent implementation of protective measures and for planning regional emergency-response scenarios.