Oil Spill Modelling

A number of models have been developed to simulate weathering processes and forecast the fate of oil once spilled.

The models follow a number of different approaches. They can range from a simple vector calculation, to sophisticated computer models of the movement and distribution of the oil in three dimensions along with predictions of the change in properties as the oil weathers.

To model the movement of oil, the most important input parameters include the type and quantity of oil spilled, along with the rate of release. Key environmental input data include wind strength and direction, ocean currents, tides and air and sea temperatures. Accuracy and availability of this data can often be an issue.

Models are widely used for contingency planning where they can be particularly helpful for decision makers. By modelling a series of the most likely oil spill scenarios, decisions concerning suitable response measures and strategic locations for stockpiling equipment and materials can be made. The locations shown to be the most vulnerable can be identified, the logistics of responding to these locations studied and response equipment placed accordingly.

Spill response training is another activity that makes use of oil spill models to allow trainees to react to simulated spill scenarios with varying circumstances.

Effective use of models during an actual emergency response can be more challenging. This is because it requires numerous input parameters, for which data may not be readily available at short notice. Usually the oil release occurs immediately after an incident. Information such as the oil type or the quantities involved may not be known. As the incident develops, more accurate data will improve the output of the model.

Although models cannot precisely predict the changes an oil undergoes, they can indicate whether an oil is likely to dissipate naturally or whether it is likely to reach the shoreline. This information can be used by spill responders to decide on the scope of initial aerial surveillance flights and/or the most effective spill response techniques to employ within the optimum timeframe.

It is important to keep in mind that models have their limitations and are no substitute for real observations (eg aerial surveillance, shoreline survey).