Dewatering the Xingu River: hydrological alterations and biocultural connections among the Arara Indigenous People in the Volta Grande region, Brazilian Amazon

In recent decades, the construction of large hydropower plants in the Brazilian Amazon has increased and has put the livelihoods of Indigenous Peoples and local communities (IPLC) at risk. The Belo Monte dam has been operating since 2015, causing the dewatering, i.e., partial diversion of Xingu River flow, of the “Volta Grande” region, where the Arara da Volta Grande do Xingu Indigenous Land is located. The objectives of the study were to (1) understand the biocultural connections between the Arara Indigenous People and the Xingu River before the dam’s operation; (2) analyze hydrological alterations in the dewatered stretch and describe the implications for the floodplain forest; and (3) elucidate how these changes affect the Arara and the Volta Grande social-ecological system. We utilized document analysis, semi-structured interviews, hydrological analysis based on the environmental flow concept, and a biocultural approach that considers the interconnectedness of human and natural systems. Results show a significant decrease in flow magnitude, higher frequency of reversing cycles of wetting and drying, increased uncertainty of the Xingu River’s dynamics, and degrading effects in the floodplain forest. Arara’s perceptions have shown the effects of their biocultural connection with Xingu River, such as the hindrance of traditional activities like fishing. Results emphasize the depreciation of the Volta Grande social-ecological system’s resilience, the necessity of developing participatory environmental flow recommendations, adopting an adaptive management approach, and the need to involve IPLC in decision-making. In addition, there is an urgent need to reconsider the current hydropower agenda in the Amazon.