Bacia hidrográfica do rio Paraíba do Sul: avaliação integrada da qualidasde das águas dos estados de Minas Gerais, Rio de Janeiro e São Paulo

Abstract

Effective management of water resources, mainly from the quality point of view, implies not only the characterization of water bodies, carried out through monitoring variables individually and analyzing them, but also the knowledge of the qualitative aspects of anthropogenic influences and their associated impacts and land usage. In view of the sustainable development concept, interaction management tools, monitoring and classification of water bodies allows quality condition and verification of compatibility with the intended uses. This study aimed to carry out an integrated analysis of water quality of the Paraíba do Sul river basin, considering data from three monitoring networks in the states of São Paulo, Minas Gerais and Rio de Janeiro, identifying the most relevant parameters of water resources degradation, as well as comparing the quality levels of watercourses with the framework standards. Non-parametric tests were applied and used multivariate (Cluster Analysis and Principal Components Analysis) to compare the quality conditions of the sub-basins. The characterization of the quality of the Paraíba do Sul river basin waters indicated that the main pressures on water resources are discharges of domestic sewage, surface drainage from development areas of farming activities, mining activities and the removal of vegetation, reflected by expressive occurrences of legal limits violations for thermotolerant coliforms, phosphorus, iron, manganese, dissolved oxygen, Biochemical oxygen demand and turbidity. The compatibility of the quality conditions of the waters with the framework classes for the variables considered showed less a favorable situation for the thermotolerant coliforms, being verified predominance incompatible quality conditions with the framework classes, which greatly restricts the use of water. Among the monitoring stations, there are stations located near urban centers, which water quality is compromised due to microbiological pollution contamination by biodegradable organic matter and solids. The results of multivariate analysis indicated consistency of formed groups and the main parameters identified explained the variability of water quality conditions for the quality of the Paraíba do Sul river basin waters and also to the geographic location of the sub-basins. It was also possible to confirm the main pressure factors in the basin.