Abstract
Understanding flow fields and mass transport processes in coral lagoons are essesntial to maintain ocean ecosystems in high bioversity regions. This study investigates mass transport processes in a lagoon associacted with pollutants discharged from an urban area of Funafuti Atoll, Tubvalu. Numerical results show that wind induced flows cause different flow patterns in the upper and lower layers. The flux of the pollutants from the urban area is estimated by simulated flow and pollutant data. In the summer season, the discharged pollutants are transported toward south and they outflow to the opne ocean through a channel on the west-south side of the lagoon, which is due to winds from the north-west. On the other hand, during winter season when east-south winds dominate, the pollutants outflow through a channel on the north side. The discharged pollutants are flushed out from the lagoon roughly ten days after the simulations started. The flush out rate is largely influienced by wind conditions. In addition, an artificial channel added in the lagoon can reduce the concentration of the pollutants by 9% in the winter season.
