Modeling Extreme Conditions of Sewage Plumes in Central – South Coastal Region of São Paulo State – Brazil

Abstract

The study region is located in the central-south coast of Sao Paulo State (Brazil), centered at 24.5°S - 46.5°W, and is influenced by three outfalls of the city of Praia Grande and sewage releases by Itanhaem River. The objective of this study is analyzed the dispersion of effluent plumes emitted by the submarine outfalls and the Itanhaem River, concerning the concentration of contaminants in extreme conditions (summer month). For that, Delft3D model’s hydrodynamic and water quality modules were used, as well as the Visual Plumes model. Results of hydrodynamic simulations were consistent with the hydrodynamics features established in the literature. The near-field modeling showed the influence of currents in the transport and initial dilution of effluent plumes. The far-field modeling’s results of the plumes from the submarine outfalls and Itanhaem River showed that those plumes do not exceed the maximum levels established by the National Environmental Council when reaching the shore. Once observations indicate that the local beaches are often classified as inappropriate for bathing and with bad water quality, streams that dump raw and untreated sewage directly on the beaches can be identified as the responsible for the environmental contamination of the study area shore.

Keywords

• marine pollution
• submarine outfall
• sewage
• numerical modeling
• water quality
• vp
• um3
• delft3d