Avaliação da qualidade da água e influência da sazonalidade em córregos urbanos reabilitados

Abstract

Brazilian urban rivers were historically channeled and covered. However, the relation between the cities’ inhabitants and their rivers has been changing in recent years, with a growing concern about ecological issues and the quality of life of the population. In Belo Horizonte, the Drenurbs Program was aimed for the rehabilitation of streams in natural beds, aiming to improve water quality and, consequently, the quality of life of the surrounding community. Thus, this study evaluated whether there was an improvement in water quality after the rehabilitation of three urban streams in Belo Horizonte. A possible change in water quality between the dry and rainy seasons was also evaluated. To evaluate that, the concentration of selected variables, before and after the interventions, was analyzed. For this, the t-test was used to analyze the results of the variables before and after the works and a factorial ANOVA was used to verify if there was a change in the pattern of concentration of water quality indicators due to seasonality. The fecal coliform parameters, BOD, total P, dissolved oxygen, total dissolved solids, water temperature and the Water Quality Index showed changes after the rehabilitation works were carried out, indicating an improvement in water quality. Regarding the seasonal pattern, total P and nitrate showed a change in their pattern between drought and rain before and after the rehabilitation. However, there was no statistical difference in fecal coliform parameters, pH, BOD and turbidity. These results demonstrate the effectiveness of the rehabilitation and warn that after remedying point pollution sources, it is also necessary to deal with the diffuse sources in urban watersheds.