Análise de hidrodinâmica ambiental e de qualidade de água na Baía de Guanabara via modelagem computacional

Abstract

The understanding of the processes that influence the quality of water in estuarine systems is key to guiding environmental management policies. These environments, when in urban areas, can be strongly impacted by anthropic actions. In this sense, this work explores the use of computational modeling to increase knowledge about the estuarine system of Guanabara Bay (BG). The study was carried out through computational simulations of hydrodynamic circulation, analysis of characteristic hydraulic times and water quality with models from SisBaHiA (www.sisbahia.coppe.ufrj.br). The results of the hydrodynamic simulations detail circulation patterns in BG in accordance with known data. The Renewal Rate and Water Age models show how exchanges in BG water mass vary in time and space. These models point out that the waters remain inland on the Bay for a long period of time. Finally, the Water Quality Models detailed spatial time distributions of BOD, OD, phosphorus and nitrogen compounds, whose knowledge is restricted to data collected at irregular times in sparse locations. The results were compared with the limits of CONAMA Resolution nº 357/2005 for class 2. In this analysis, the western region of the BG was indicated with worse results for BOD, OD and nitrogen. It is advised new studies with measured data of all its inorganic compounds of nitrogen. In the analysis of total phosphorus, almost all extension of the BG is in disagreement with the parameters of the legislation. In general, the results refine and broaden more generic studies, such as the Environmental Health Score generated in the Projeto de Recuperação Ambiental (PRA-Bahia). In order to increase the reliability of the models, and their application as a management tool, it is recommended to use computer models in an integrated way to the data monitoring.