Bacia hidrográfica do rio Paraopeba : análise integrada dos diferentes impactos antrópicos

Abstract

The quality of surface water reflects the influence of various human activities associated with the population explosion. These activities end up generating conflicts that compromise natural resources. The Paraopeba River basin is compromised by several of these activities, with its environmental condition worsened by the rupture of Dam I, of the Córrego do Feijão mine, belonging to the mining company Vale SA, located in Brumadinho, in the Metropolitan Region of Belo Horizonte, in January 2019. In this context, to provide significant suggestions to planners and managers for better protection of water resources, the characterization of the Paraopeba River basin in its demographic, geographic, economic, social, and environmental aspects was carried out; the analysis of the relationship between the concentrations of pollutants in the hydrographic basin and the use and occupation of the soil, the identification of patterns of variation in water quality in the monitored watercourses, before and after the collapse of Dam I, and in the supply reservoirs, thus identifying the potential sources of pollution in the hydrographic basin. For the evaluations, statistical tools were applied, including non-parametric hypothesis tests. An index of compliance with the classification was used to compare the observed values of the water quality parameters with values recommended by the Joint Normative Deliberation COPAM/CERH-MG nº. 01/2008 for each classification class. In the period before the dam's failure, the Areias/Pedras stream, in the municipality of Betim, had the highest number of parameters with concentrations that violated the limits recommended in the legislation, being, therefore, the most impacted body of water in the Paraopeba river basin, mainly due to the discharge of domestic sewage. Regarding the impacts generated by the dam failure, it is noteworthy that the stations located just downstream of the dam rupture, in the municipalities of Brumadinho, São Joaquim de Bicas, and Betim were the most impacted, however, impacts can be observed throughout the trough of the river Paraopeba. The quality parameters that most violated the legal limits were: fecal contamination indicator, total manganese, and total phosphorus. The index values calculated for the rainy season were lower when compared to those obtained in the dry season, indicating a greater deterioration of water quality in the rainy season. Thus, this research contributes to the debate on the effect of the pressure of economic activities in hydrographic basins located in metropolitan regions and the environmental consequences influenced by human activities, bringing information about the most contaminated areas that need more attention and recovery actions and conservation so that the proposed framework be respected.