Numerical modelling of tidal fluxes and passive pollutants concentration in Ria de Aveiro, Portugal

Abstract

Ria de Aveiro is a shallow lagoon in the North of Portugal, extremely polluted, mainly as a consequence of the big chemical industries located in its neighbourhood. The purpose of this work is to predict tidal flow fields as well as passive pollutants transport processes in the lagoon, to better understand its normal behaviour and the consequence of the discharges of pollutants in situ. A two-dimensional finite difference numerical model, capable of predicting depth averaged tidal flow fields in estuarine waters has been adapted and extended to this area. The partial differential equations governing the conservation of mass and momentum in an incompressible turbulent flow are included in a depth-integrated form in the model. The results reveal that bathymetry and coastal morphology strongly influence the circulation patterns and the pollutants concentration distribution in Ria de Aveiro. It is also possible to conclude that the dynamics of Ria de Aveiro is predominantly governed by the tidal wave which spreads the pollutants through almost all the lagoon.