Resiliência dos recursos hídricos pós-rompimento da barragem de rejeitos em Brumadinho, MG

Abstract

The rupture of Dam I in the city of Brumadinho-MG, on January 25, 2019, caused human deaths, socioeconomic impacts and various environmental damages, including water resources. A large volume of iron mining tailings from the Córrego do Feijão mine traveled along the Ferro-Carvão stream and reached the Paraopeba river, causing an interruption in water collection. Therefore, the main purpose of the present study was to evaluate the conditions of resilience of water resources, post-rupture. For this, a characterization of the study area was carried out, which corresponds to the Paraopeba river basin, in relation to the physical, biotic and management aspects of water resources, and subsequently by analyzing data from pluviometric and fluviometric monitoring of that basin. The probable origins of the chemical elements evaluated in the present work were investigated, with the purpose of identifying the main geogenic and anthropic origins; this compilation of information made it possible to identify probable delay factors in the resilience process. Sequentially, three Resilience Indexes were elaborated and determined, capable of portraying the water quality conditions before the failure, in the period from 2000 to 2018. For the elaboration of the Indexes, minimum, average and maximum values of eight water quality monitoring stations of the Instituto Mineiro de Gestão das Águas (IGAM), installed on the Paraopeba River, were used. In addition to the values from the monitoring stations, the average values of monthly precipitation in the basin were used, which were considered in the creation of one of the three Resilience Indexes, with the aid of mathematical modeling. The post-rupture values, obtained between January 2019 and December 2022, were applied to the certain indices. This application indicated the annual resilience of the Dissolved Copper and Total Mercury parameters, according to the three proposed indices, and the Total Lead, only according to one of the proposed Indexes. The annual resilience conditions of dissolved aluminum, dissolved iron, total manganese and turbidity were not yet satisfactory according to the proposed Indexes. In a general view, despite the advances obtained with the retention and removal of tailings from Vale S.A., the conditions before the rupture have not yet been re-established, until the year 2022, being of great importance the continuity of the repair actions and the monitoring of quality of the waters of the Paraopeba river.