Socioenvironmental impacts of the Belo Monte hydroelectric power plant as revealed by Indigenous and ribeirinho monitoring.

Hydroelectric dams, once seen as clean and renewable energy sources, have been the subject of extensive research, particularly concerning their socioenvironmental impacts. The Belo Monte hydroelectric power plant (HPP) relies on the operation of 2 dams that divert water from a 130-km stretch of the Xingu River to generate energy. The dam has disrupted the seasonal flooding cycle (flood pulse) along the Volta Grande do Xingu (VGX) and created a reduced discharge condition analogous to a prolonged and extreme dry season in the watershed. Before the Belo Monte HPP, local communities relied on the highly diverse and abundant fish assemblage supported by seasonal flooding of the ecosystem. Local VGX residents sought partnerships and established the Independent Territorial Environmental Monitoring Program (MATI-VGX). Through this program, locals monitored fish spawning sites and fishing dynamics. This monitoring complemented and quantified local communities' perceptions about the environmental impacts caused by the Belo Monte HPP. The HPP was associated with a water discharge shortage that critically undermined the river's capacity to sustain vital ecosystem processes that support local people's lives. Drastic transformations of traditional lifestyles, shifts in fishing practices, and a significant decline in fishing yield occurred that jeopardized food sovereignty and security. The Belo Monte HPP environmental licensing process ignored local ecological knowledge and the vital links among the river's flood pulse, the aquatic and seasonally flooded ecosystems, and the traditional lifestyles of VGX residents. To ensure the ecological sustainability of the VGX, the Belo Monte HPP operation needs to change to support key spawning areas, maintain water discharge, avoid short-term water fluctuations, and emulate natural interannual discharge variability to mitigate flood pulse disruption. Local ecological knowledge should never be ignored in projects where local communities are the most affected. These communities should be central in decision-making regarding socioenvironmental impact assessment, mitigation, and monitoring.