Dynamic modeling of effluent dispersion on Mangueira bay — Patos Lagoon (Brazil)

The city of Rio Grande, located in the south of Brazil, suffers with the inadequate coverage of its network of sewage collection and treatment. In addition, there are clandestine effluents ducts being launched in the Mangueira bay, a region of extreme economic and ecological importance. This article aims to understand the influence of the Patos lagoon hydrodynamics, as well as inside the bay, in the behavior effluents dispersion in two different conditions: flood and ebb events. Further, the assessment of local pollution analyzing indicators of the contamination degree was performed. For the development of this study a hydrodynamic model TELEMAC-3D coupled to a dispersion pollutant model were applied. The results indicate that minor parts of the pollutants are dispersed outward the bay, whilst the bay is the most susceptible site to contamination since a large part of pollutants remain trapped in this region.