Oil spills in the marine environment cannot be prevented entirely. In order to diminish their consequences,
numerous oil spreading and weathering models have been developed. The NAFTA3d
model is based on the particle tracking method, its results are oil concentrations at specified
times. A new module based on the trajectory method showing the probability of oil slick occurrence
was added to the model. The thesis first describes theoretical background of mathematical
oil spill modelling in the marine environment as wall as the course and demands of an oil spill
response. We show possible further development of the trajectory method. The second part
describes both methods and functioning of the model. A graphic printout automation program
developed in the scope of the thesis is presented. In the third part we present the results of
performed simulations and analyse the suitability of the trajectory method by comparing concentrations
and trajectories in the Gulf of Trieste and in the Northern Adriatic. We depict the
strengths and weaknesses of the trajectory method. The study reveals that the new module is
most suitable for oil spill response modelling, its major advantages being high computational
speed as well as simple and efficient presentation of the entire area at risk on a single map.
Finally, we propose a procedure for practical use of the trajectory method.