Integrating economy, ecology and uncertainty in an oil-spill DSS: The Prestige accident in Spain, 2002

Major accidental oil spills still affect sensitive marine areas and shorelines around the world, constituting a challenge for operational as well as strategic contingency management. As a rationale basis for addressing both issues we here propose a Decision Support System (DSS) consisting of a combination of modelling and evaluation methods which in particular assesses various impacts on habitats and local economies. By integrating the state-of-the-art oil spill contingency simulation system OSCAR with wind and current forecasts, environmental GIS data and multi-criteria analysis techniques, the DSS is able to rank different response actions to a chemical or oil spill. In this study, the usefulness of the approach is tested by hindcasting the Prestige accident off the coast of Spain in 2002. In particular, the short- to mid-term economic and ecological consequences of different mitigation measures are estimated. We identified clearly one worst option matching the actual decision taken by the responsible parties and one or two almost equally well performing routes. Two procedures of including uncertainty at various stages of the DSS are tested. The first method averages ensembles of outcomes between each modelling/evaluation stage, while the second one preserves the entire degree of freedom till the final ranking procedure. Results in the Prestige case turned out to be rather insensitive against both ways to account for uncertainties. The robustness as well as clarity of the DSS has the potential to enhance the efficiency of decision making even in politically sensitive situations. Limitations as well as ongoing improvements of the system are highlighted, in particular emphasizing linkages to environmental economics.