3.3.2 Operational application

The produced operational code was adapted to the environment of a coastal basin of NW Aegean Sea (39.96°–40.66° N, 22.50°–23.40° E), namely Thermaikos bay, which also includes Thessaloniki's gulf [41]. The area that has been selected to be studied is shown in Figure 9 [42], with a horizontal discretization of 1°/30

Figure 9. Thermaikos bay and ships' route to and from the port of Thessaloniki.

Figure 10. Thermaikos bay bathymetry.

Figure 11.

Snapshots of the spatiotemporal evolution of an oil spill hypothetically released near the coast of Chalkidiki, at the east side of Thermaikos bay, after: (a) 36 h, (b) 72 h, (c) 108 h, (d) 144 h, and (e) 180 h.

(Dx = 2800 m, Dy = 3700 m). The commercial port of Thessaloniki provides a good study area, as it is enclosed in Thermaikos bay with an important coastline and a busy oil terminal. Although the terminal operates under strict IMO (International Maritime Organization) and EU (European Union) regulations for oil terminal operational safety, the port area is a potential oil slick accidental source [38].

The transport and fate of the slick are closely related to the hydrodynamic conditions in the bay, the bay morphology and the oil properties. The hydrodynamic circulation in the bay is sustained mainly by the strong NW to NE winds and the circulation patterns are regulated by the bay bathymetry and the coastal topography (Figure 10). Following a thorough consideration, the period of data selected to be used from the POSEIDON dataset was a winter week of January (21–28/01/ 2014) which exhibited significant winds, able to transport the oil slick and produce substantial results. The data were given for 29 time steps (6 hrs. each). The POSEI-DON dataset for the Aegean Sea offers 3D hydrodynamic forecasts (POM) nested to POSEIDON Med forecast, for the depth levels of 5, 15, 30, 50, 80, and 120 m. The depth in the area under study, as shown in Figure 10, is less than 100 m. One hypothetical oil spill scenario has been selected to portray the model's simulation capabilities and results, at the east side of Thermaikos bay, near the touristic areas of Chalkidiki (Figure 11). An oil spill of 5000 parcels, representing an estimated total volume of 10,000 tn, was hypothetically released instantaneously on the sea surface. Total simulation run was for 180 hrs (7.5 days). Figure 11 presents snapshots of the spatiotemporal evolution of the oil slick at a 36-hr step after the release. The touristic coast of Chalkidiki is damaged within some hours after the spillage (clearly after 2–3 days). The dispersion effect is also revealed showing that the oil slick diameter is moderately increasing during this time.
