Development of an oil spill hazard scenarios database for risk assessment

The occurrence of oil spills in coastal regions may have catastrophic consequences on the environment and severe socio-economic impacts. This work presents a new methodology to evaluate the risk associated with oil spills in coastal zones and estuaries, and illustrates its application in a coastal lagoon (Ria de Aveiro, Portugal). A ranked list of the hydrodynamic scenarios under which oil spills are most likely generated through the analysis of 33 years of wave and wind data, retrieved from the ERA-INTERIM project database, and from the analysis of oil spills that occurred in the Atlantic Iberian shelf. Considering six spill locations and a single oil type spill inside the Aveiro harbor, the database resulted in approximately 3500 simulations. Hydrodynamic simulations were made with the MORSYS2D modeling system, a soft coupling of the hydrodynamic model ELCIRC and the wave model SWAN. The high-accuracy, unstructured grid, oil fate model VOILS was used in 2D mode to simulate the transport and the oil weathering processes at the surface and in the intertidal areas. The hazard assessment analysis included the determination of the trajectory of the plumes, the shoreline retention areas affected by the oil and their oil exposure time. Time evolution of the oil properties, such as the oil evaporation rate and emulsification processes of the mixture, are provided to support clean-up operations, as well as robustness controls such as oil mass balance.