A risk estimation of marine oil spills by major ports and sea areas in South Korea : Using Markov chain and risk matrix

The explosion of the Deepwater Horizon, an oil tanker of BP, caused a large amount of crude oil spill in 2010. In South Korea, two large-scale marine pollution accidents occurred: 'sea prince oil spill accident' off the coast of Busan in 1996 and 'Hebei Spirit oil spill accident' off the coast Taean in 2007. Marine accidents during transport cause widespread direct and indirect damage, such as human damage, property losses, economic damage, and environmental pollution. Especially, in case of large-scale oil spill occurs, it has a serious adverse effect on the environment around the affected area, such as population outflow, regional economic downturn, and intensification of community conflict. The probability of marine pollution accidents is increasing due to changes in the trade environment, such as the expansion of world seaborne transportation volume, as well as enlargement and speeding up of ships. In addition, the potential risk of marine pollution accidents is increasing due to the expansion of marine areas use, such as the installation of offshore plants, and the deterioration of weather conditions caused by climate change. In order to mitigate the damage from oil spills during maritime transportation, it is necessary to prepare safety management strategies based on risk prediction. The purpose of this study is twofold: ⅰ) to propose a risk estimating approach of oil spill accident by constructing a probabilistic risk matrix (4×4) using the Markov chain process. ⅱ)  to compare the risks by sea area, including major ports in South Korea: Central, West, South, East, and Jeju. Analysis data was used with detailed marine pollution accidents provided by the Korea Coast Guard. 84 months of accident data were collected over 7 years from 2017 to 2023. In this study, the risk matrix proposed by the International Maritime Organization (IMO) was used, and the levels of the risk matrix was divided into 4: attention, caution, alert, and serious, as specified in the crisis alerts management manual of marine pollution accidents in South Korea. The risk of each sea area could be quantified by comprehensively considering the monthly occurrence frequency of accidents and the volume of oil spills. In addition, by applying the probability value through Markov chain process to the risk matrix, the uncertainty of the risk analysis data could be reduced and risk level could be classified more clearly and quantitatively based on accident data. The results can be used as basic data for decision-making on the allocation of resources and budgets for policies to prevent marine pollution accidents.