Circulation and Lagrangian Dispersal in the Gulf of Vlora (Albania)

Hydrodynamic and pollutant transport models are useful tools for evaluating remediation options for polluted water bodies. In this work, a Lagrangian-partide approach is used to simulate the three-dimensional pollutants transport in the Gulf of Vlora (Albania) coming from the fresh water outflow from the Vjosa River located in the northern sector of the gulf. Results indicate that the sedimentation processes are strongly dependent on the local meteorology, which is able to modify considerably the circulation of the gulf. Numerical simulations were used to estimate the water circulation and the fate of pollutants in different meteo-oceanographic scenarios identified by the analysis of the oceanographic data collected during two oceanographic cruises carried on during the Centro Internazionale di Scienze del Mare (CISM) project. Suspended sediments are simulated by a large number of Lagrangian elements, the trajectories of which are drawn on the basis of the sea current, settling velocity, and dispersion phenomena. The model was calibrated on the basis of biogeochemical experimental data consisting of concentrations of metals measured in water and in bottom samples, collected during the CISM project performed in the framework of the Interreg III Italia-Albania program. Results of the simulations show that the pollutants coming from the river tend to spread rapidly and undergo rapid dilution for southern and eastern wind regimes. Under northern and western winds a variable percentage of the fine-grained part of sediments discharged by the river penetrates and settles inside the gulf, in accordance with the experimental data.