Hierarchical Optimization of Oil Spill Response Vessels in Cases of Accidental Pollution of Bays and Coves

Abstract

Ships pollute bays and coves with oils daily. Although the number of major pollution events is decreasing, accidents still occur and are likely to occur in the future. Most often, pollution arises from spills of non-persistent oil in bays, mainly during the summer season. A prompt response is key to oil collection success in semi-enclosed waters. In order to ensure that oil does not reach the mainland and endanger a potentially crucial economic resource of a country, it is vital to collect it in minimal time. Furthermore, it is also essential to send response ships that minimize the cost. In practice, there may be several optimal combinations of response ships to be sent. When the response cost is considered, obtaining all possible optimal solutions (a complete Pareto front) is vital because the shortest collection time does not necessarily mean the lowest costs. For these reasons, two general optimization models are considered. The first model gives the minimum response time to collect oil from the sea’s surface, while the second model gives the minimum response cost of ships participating in the clean-up operation. The supplied pseudo-codes allow for all optimal solutions to be found.