The OSCAR model system has been developed to supply a tool for objective analysis of alternative spill response strategies. OSCAR is intended to help achieve a balance between the cost of preparedness in the form of available, maintained spill response capability on the one hand, and potential environmental impacts on the other. Although it is always theoretically possible to purchase more equipment, or a higher level of preparedness, the marginal value, in terms of reduced environmental impacts, of each additional purchase tends to decrease. OSCAR is a tool that directly and objectively addresses this trade-off.
Key components of the system (Reed et al, 1995a; Aamo et al, 1996) are SINTEF's data-based oil weathering model (Aamo et al, 1993; Daling et al, 1990, 1991), a three-dimensional oil trajectory and chemical fates model (Reed et al, 1995b), an oil spill combat model (Aamo et al, 1995, 1996), and exposure models for fish and ichthyoplankton (Reed et al, 1995a, 1996a), birds, and marine mammals (Downing and Reed, 1996).
OSCAR has been applied to the analysis of alternative oil spill response strategies for both offshore platforms (Aamo et al, 1995; Reed et al, 1995a) and coastal terminals (Reed et al, 1996b). OSCAR provides, for alternative spill response strategies, a basis for comprehensive, quantitative environmental impact assessments in the marine environment. The model calculates and records the distribution in three physical dimensions plus time of a contaminant on the water surface, along shorelines, in the water column, and in the sediments. The model is embedded within a graphical user interface in WINDOWS NT, which facilitates linkages to a variety of standard and customised databases and tools. These latter allow the user to create or import wind time series, current fields, and grids of arbitrary spatial resolution, and to map and graph model outputs.
Oil and chemical databases supply chemical and toxicological parameters required by the model. Results of model simulations are stored at discrete time-steps in computer files, which are then available as input to one or more biological exposure models.
OSCAR employs surface spreading, advection, entrainment, emulsification, and volatilisation algorithms to determine transport and fate at the surface. In the water column, horizontal and vertical advection and dispersion of entrained and dissolved hydrocarbons are simulated by random walk procedures. Partitioning between particulate-adsorbed and dissolved states is calculated based on linear equilibrium theory. The contaminant fraction that is adsorbed to suspended particulate matter settles with the particles. Contaminants at the bottom are mixed into the underlying sediments, and may dissolve back into the water. Degradation in water and sediments is represented as a first order decay process.
The algorithms used to simulate these processes controlling physical fates of substances are described in Aamo et al (1993) and Reed et al (1994, 1995a, b).
Case Study # 1.pdf
For further information,
Please contact Mark Reed, Ivar Singsaas or Per Daling.
