Influence of the Rio Taquaraçu in the water quality of the Rio das Velhas: subsidies for reflections of the case of water shortage in Belo Horizonte metropolitan region – MG, Brazil

ABSTRACT Southeastern Brazil is experiencing severe water scarcity because of low rainfall and inefficient water resource management. As a consequence, water supply companies have begun discussing potential solutions to this problem. One proposed solution is creation of new public water supply reservoirs. Recently, managers from municipalities in the metropolitan region of Belo Horizonte, along with sanitation companies, have begun to focus their attention on the Rio Taquaraçu. The Taquaraçu lies in the Rio das Velhas Basin and displays both good water quantity and quality within the Belo Horizonte metropolitan area. The Taquaraçu is a tributary of the Rio das Velhas, and it was proposed that the Taquaraçu waters dilute pollutant concentrations entering the Rio das Velhas, thereby improving downstream water quality. This study evaluated statistically the impact of the Rio Taquaraçu on water quality in the Rio das Velhas. For this analysis, we used data collected between 1997 and 2015 from sampling points established by the Minas Gerais Estate Institute of Water Management(IGAM) in the Rio Vermelho, in the Rio Taquaraçu, and in upstream and downstream sites (the Rio Taquaraçu input) of the Rio das Velhas. Box-plots were created for water quality variables and a Principal Component Analysis (PCA) was run for periods referred to as “dry” and “wet.” Despite receiving sewage releases from cities in its watershed, the Rio Taquaraçu maintains good water quality. Nevertheless, our results indicate that inflow from the Rio Taquaraçu is insufficient to mitigate the poor water quality of the Rio das Velhas.