This report addresses marine oil spill trajectory modeling and Environmental severity Index mapping with a focus on the Kerala coastal environment. With growing Indian demand for the crude oil the Kerala coastal area will be exposed to increasing risk of oil spills from marine transport. Oil spill trajectory models are an essential tool for risk assessment related to potential environmental impacts in sensitive areas for Kerala coast and for planning spill response measures. This study is a review of the oil spill modeling literature, special emphasis was given to the physical, biological and ecological coastal area of Kerala having 590Km of coastal line. The first goal is a synthesis of the oil spill trajectory modeling and its various components. The second goal is the identification of the most vulnerable areas to oil spill in the coastal belts of Kerala. A comprehensive oil spill trajectory model for the Kerala coastal area would include: 1) Models for the physical environment (Wind, air temperature, precipitation, ocean currents, and waves), 2) An oil spill model to address weathering, evaporation, and other details of the oil's interplay with the marine environment.