Extracting and traorting a significant part of oil in marine environment are the most important sources of oil spill at seas. Since the release oil in water is harmful and brings damages to ecosystem and coastlines, cleaning oil from water surface is extremely important. One of the methods for removing the oil pollution is to use oil cleaning vessels. Due to harmful effects of pollution in water, decreasing the time of cleaning process to the shortest possible time and minimizing cleaning costs based on the volume of oil spill is essential. Due to existence of many oil fields and terminals in the Persian Gulf, the goal of present study is to prepare best scenarios for oil cleaning from sea surface in this region using oil cleaning vessels. Therefore, in this study the optimal position vector of oil cleaning vessels is determined for which the oil slick cleans up in a minimized time. For this purpose, at first the oil slick behavior is identified. Due to importance of oil cleaning up which is less than 36 hours and no affordable of oil cleansing after this time, an optimization model based on short-term numerical modeling for oil spill simulation with considering spreading and depreciation of oil slick in the Persian Gulf has been developed. In this model, volume changes of oil slick base on depreciation processes: evaporation and emulsification are considered. It is noticeable that, these depreciation processes have a dominant share at the beginning of oil released into the marine environment than other processes. After preparing the optimization model, because the objective function does not have the property to be differentiable and is not linear, Genetic Algorithm is used to determine optimal position of the oil cleaning vessels by considering the velocity and cleaning capacity of vessels for different scenario of oil spill. Maximum number of vessels that used in this study for cleanup operations is 10 vessels. Cleaning equipment of these vessels (boom and skimmers) is on the board of the vessels and therefore these vessels are quickly dispatched to the polluted area. Also, by some engineering assumptions, optimal position of vessels applicable to all oil spill scenarios is obtained and the optimal positions with five vessels are presented for West and East region of the Persian Gulf. Then, a methodology developed for performance of oil spill risk analysis in the Persian Gulf. This methodology concerns the processes of probability and consequence assessment. The two processes are accomplished qualitatively with a risk prioritization based on Analytic Hierarchy Process (AHP). Being a decision-making technique, Analytic Hierarchy Process can only be used after some appropriate modifications, which transform it into a tool for prioritizing risks with respect to their probability and consequence in different oil spill scenarios. This is an approach that attempts to rationalize the risk analysis stages and to indicate the uncertainties imposed to the problem, hence creating a basis for optimization of the risk analysis results. Finally, the optimal position results from the Genetic Algorithm have been validated with the results of oil spill risk map. Key word: Oil cleaning vessels, Oil pollution, Persian Gulf, Risk Map, Genetic Algorithm
