# Ship Route Oil Spill Modeling: A Case Study of the Northeast Brazil Event, 2019
## 1 Introduction  
The oil industry poses the highest risk of environmental accidents, with the likelihood of spills occurring at every stage of its operations, from drilling to distribution [1; 2]. The increasing globalization and demand for fossil fuels have led to a rise in the maritime transportation of oil and its derivatives [3]. After significant fluctuations in volume transported before the 1990s, stabilization occurred in the following years, and the average oil trade volume was around 10,000 ton-miles per year. Crude oil seaborne trade has a significant share of the total world seaborne trade. Currently, tanker movements comprise approximately 80% crude oil and about 20% oil product [4]. While the increase in maritime transportation might suggest a greater probability of environmental risks, a decreasing trend in the frequency of maritime oil spills continues despite growing global demand. The demand for oil has increased tanker traffic between countries around the world, which increases the risks of both accidental and intentional maritime oil spills. The maritime transportation of crude oil has expanded since the early 19 th century to meet the growing demand of the global market. Currently, over 90% of oil transportation around the world is carried out through tanker ships [5]. It is estimated thatoil spills from tankers constitute approximately 13% of all oceanic oil pollution [6]. It is crucial, therefore, to look into the characteristics of these tanker ships in case they are involved in oil spills accidents. Oil-carrying ships are divided into five main categories according to their tank volume: Panamax (60,000 to 79,999 dwt), Aframax (80,000 to 119,999 dwt), Suezmax (120,000 to 199,999 dwt), VLCC, and ULCC (200,000 dwt and above). The shipping routes of tanker ships are recorded and well established, and the navigation data provided by the Automatic Identification System (AIS) allow for their immediate identification. AIS is an international maritime security communication system that uses ship tracking equipment to monitor the activities of cargo ships worldwide [7]. AIS allows for the identification of potential causes of oil discharge at sea, the evaluation of ship routes, and their distances from sensitive environmental areas. Despite technological advancements to protect oil transportation operations, including improving safety conditions, implementing sophisticated monitoring, and accident prevention by authorities [8], maritime oil transportation still presents high risks to the environment and society [9]. Nevertheless, the total number of maritime oil spill accidents has decreased in the last 50 years, likely due to increased attention from government agencies around the world to oil spill accidents and improvements in communication and technology related to oil transportation [4]. While large ships optimize oil transportation, their accidents pose serious spill risks. The basis of risk-based ship design has been highlighted in numerous studies [10; 11; 12; 13]. It is important to consider a ship's deadweight tonnage (DWT) to identify mobile oil leak sources. This can be achieved by linking AIS data and taking into account weathering processes to determine the quantity of oil reaching the coastline. This approach integrates the formal safety analysis (FSA) of the International Maritime Organization (IMO) and stresses the need to explicitly consider risks in ship design for safer and more sustainable maritime transport [14; 15; 16; 17]. In one study [13], a qualitative analysis revealed a spilled volume ranging from 5000 to 45,000 m\({}^{3}\) of crude oil, which aligns with the order of magnitude of oily residues found on the Brazilian coast in the event of 2019 (approximately 5000 tons). Oil spills in marine and coastal environments represent a serious and damaging socio-environmental threat. The release of oil and its derivatives into the oceans can have significant effects on economic activities and the environment, both in acute and chronic spills.