Impact of marine oil spills to Sri Lanka and it's numerical modelling

Abstract

Over the last couple of decades there has been a growing concern regarding the marine pollution due to spill of oil from ship operations and accidents. This is because the oil spills have devastation and obnoxious effect on marine ecology, which may not be recovered. Hence, there is a need for analyzing or predicting the movement of spilled oil slicks. The occurrence of oil spills is fundamentally a matter of probability. There is no certainty regarding the amount of oil that would be transported, or the size or likelihood of a spill that would occur, during the period where the predication is carried out. Neither can the winds and ocean currents that transport oil spills be known for certain. A probabilistic event such as an oil-spill occurrence or oil-spill contact to an environmentally sensitive area cannot be predicted with certainty. Only an estimate of its likelihood (its probability) and the vulnerability of such sensitive resources can be quantified. Such estimations can easily be done with the help of advanced computer modelling techniques. Numerical models have various aspects and various modelling methods based on the level of the accuracy required by the purpose it is being used. In this study, impact of marine oil spills to South west coast of Sri Lanka has been investigated using available numerical modelling techniques combined with a set of available environmental data. The extensive amount of modelling work was carried out in areas where the overall sensitivity ofthe coastal zone is high. OILMAP _4, an oil spill probability and fate model developed by Advanced Science Associates of USA has been used for all the modelling work and in house model developed by Wijeratne (1997) was used for exploring the numerical modelling techniques. Having identified the areas most exposed to potential oil spills, the methodology was proposed to assess risk involved in each area by a method of risk score allocation. Such a scoring method directly reflects the lc:vel of attention need to pay regarding preventive measures and planning for response operations. Based on the results of modelling and risk assessment there is a strong and urgent demand for well prepared plan to meet those circumstances. Hence scope of the study is extended to identify the requirement of an oil spill contingency management plan and its development guidelines.