Assessing lagoon plume dispersion under variable metocean conditions

Coastal lagoons are ecologically sensitive environments that are highly vulnerable to anthropogenic pressures and pollutant dispersal. Understanding how pollutants move within these systems lays the groundwork for managing water quality and mitigating the risks associated with pollution events. In this study, we investigate the dispersion of floating virtual particles released near a sewage outfall in the Narta Lagoon, Albania, using Lagrangian particle tracking under six weekly meteo-oceanographic (metocean) scenarios. Two release configurations are analyzed: a single (instantaneous) release and a continuous (periodic) release. Our results demonstrate that plume dispersion is significantly influenced by hydrodynamic conditions, with advective flow playing a dominant role in determining plume behavior. In some scenarios, dispersion is sensitive to release timing, with particles either remaining close to the release area or being more uniformly dispersed across the lagoon. Exposure maps highlight boundary accumulation zones, while dispersion descriptors reveal contrasting mixing patterns between scenarios. These findings provide new insight into the transport and retention dynamics that govern floating-particle behavior in the Narta Lagoon, underscoring the importance of properly managing the two inlets.