Numerical analysis of oil spill scenarios in harbour areas with an Eulerian approach: The Augusta case

Even if they are limited, oil spills remain a significant problem on a global level, especially in port areas characterized by intense naval traffic. In preparing emergency plans, it is essential to define the risks associated with the potential dispersion of pollutants. Therefore, due to the lack of adequate databases, the possibility of hazardous events could be evaluated through numerical simulations. To evaluate the influence of the different processes taking place in an oil spill for a real case, thousands of oil spill scenarios were simulated with an Eulerian approach for the Port of Augusta (Sicily, Italy), varying the source point, the weather and sea conditions, the types of crude oil, the emulsification level, and the volumes spilled. The results show that for a light crude oil spilled volume of 10000m3, with unstable emulsification, the time scale for the interaction with the coast is a few hours, with sea areas affected by the slick of a few km2 and contaminated coasts up to 7.5km in mean. The stable emulsification causes a doubling of the slick area and a strong increase in the contaminated coast. By reducing the intensity of the wind or the friction forces on the slick, a delay in the evolution of the contaminant is observed, and an increase in the area of the slick and contaminated coast due to more extensive diffusion processes. Due to the complex geometric characteristics, the scenarios show very variable results; on a statistical level, to reach a confidence level above 90%, it is necessary to consider two standard deviations of the mean.