          ASU INAN 1 , LALE BALAS 2 1 Institute Science & Technology 2 Civil Engineering Department Gazi University Gazi University Technology Faculty 06550 Teknikokullar/ Ankara TURKEY 1 asuinan@gazi.edu.tr , http://www.fbe.gazi.edu.tr/kazalar/English/asuinani.htm 2 lalebal@gazi.edu.tr , http://www.mmf.gazi.edu.tr/insaat/english/academicstaff/cv/lalebalasi.htm  Oil tanker accidents in seas cause serious problems to marine environment, especially when these accidents occur close to coastlines. To minimize the impact of tanker accidents on marine environment some measures might be taken if oil slick movement could be predicted in advance. Oil spill trajectory and fate models have been developed since the early 1960’s to simulate oil movement on the water surface in order to take immediate action and some necessary measures after such accidents. Mediterranean Sea being among the world’s busiest waterways is many times subject to oil spill accidents. In this connection a study has been carried out by giving special attention to Mersin coastlines. In this study, a 29D Oil Spill Model has been developed and applied to Mersin Coastlines. The model is based on the 29D oil spreading equation and considers horizontal dispersion, advection, diffusion, evaporation and shoreline deposition. Since evaporation process is the main cause of rapid volume reduction during the fate of oil spill, a special emphasize has been given to its modeling.  Numerical modeling, oil spill, oil slick movement, pollution, advection, diffusion.   Oil spilling on the sea is very important phenomena as the oil industry and oil transportation develop. It has dangerous effects on the ocean ecological environment [1]. In Table 1, the sources of oil pollution into the sea that were estimated by the United Nations Environment Programme have been shown [2]. Table 1: Sources of oil pollution into the sea [3] Recorded Sources Distribution (%) Industrial waste, urban runoffs etc. 60.7 Refineries/ terminals 1.2 Natural sources 10.3 Tanker operations 6.6 Tanker accidents 4.7 Other shipping 14.4 Offshore production 2.1 Total 100 The major source of oil pollution in the seas is industrial waste water discharges. But the accidental oil spills which are caused by the collision of oil tankers and irrational dumping of ballast water from ships are significant source of coastal pollution in Mediterranean Sea [4]. As the maritime traffic increases, oil spill accidents will be occur. The causal distribution of spills for oil tankers between the years 197492000 has given in table 2 whose data were obtained from International Tanker Owners Pollution Federation [5]. Table 2 shows the importance of the oil spill clearly. Hazard identification, risk assessment, risk control options, cost benefit assessment and recommendations should be prepared for oil spill accident [3]. Therefore the oil slick movement should be simulated by an oil spill model. WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT Asu Inan, Lale Balas ISSN: 1790-5079 345 Issue 5, Volume 6, May 2010