Análise hidro-espacial da rede de monitoramento da bacia hidrográfica do rio Itabirito: discussões e proposições sobre as influências do uso e ocupação do solo no gerenciamento hídrico

Abstract

The das Velhas river basin is located in the central region of the State of Minas Gerais, encompasses, in whole or in part, 51 municipalities, and a total population of 4,403,860 inhabitants, which represents 24.7% of the state's population. The hydrographic region of Alto Rio das Velhas is considered highly complex, in terms of socio-environmental pressures and weaknesses, marked by conflicting interests in the territory management process, to the detriment of water resources policies. The concentration of economic activities, urban expansion, industrial and mining activities, converging with the contribution area of the source of the Velhas River, demonstrates the vulnerability of the system, as it is a run-of-river. The Itabirito river basin is the main contribution area for the Velhas river in terms of water quantity, however, considering the qualitative aspects, it has several interferences associated with the forms of land use and occupation, causing the quality to deteriorate considerably, directly affecting the public supply system of the RMBH. In this sense, the territory has great strategic relevance, both in the environmental scope, being a “water producer” territory, and of a social, economic and political nature for the Velhas river basin as a whole. In view of the above, this work aimed to identify the most critical points in the water quality of the Itabirito river basin, analyzing in an integrated way the land use and occupation data and the monitoring system carried out by IGAM, considering the water quality data in the period between 2005 and 2021. For this purpose, geospatial evaluations were carried out, correlating land use and occupation map with the multivariate statistical method, jointly applying Principal Component Analysis and Cluster Analysis, also verifying the violations that occurred within the scope of CONAMA Resolution No. 357/2005.The results showed that the most relevant variables in the variability were: Total Chloride, BOD, Total Phosphorus, Nitrite, Total Ammoniacal Nitrogen, Total Dissolved Solids and Turbidity, which have greater similarity with the BV 035 Station (Downstream of the City of Itabirito), being associated with the release of domestic and industrial sewage, as well as surface runoff from erosion and mining processes. Finally, an action plan was drawn up with structural and structuring measures to improve the basin's management system.