Dams Pose a Critical Threat to Rivers in Brazil's Cerrado Hotspot.

Hydropower dams are touted as one of the cleanest forms of energy production, yet they are associated with severe environmental impacts on both the physical structure and functioning of river ecosystems. The threat is particularly acute in the Brazilian Cerrado—a biodiverse savanna region, spanning over 2 million km², that concentrates the headwaters of several critical South American watersheds. Our study analyzed the current distribution of large and small hydroelectric plants in the Cerrado and focused on understanding their effect on land use changes. We also propose a Dam Saturation Index (DSI) to help spur more integrated planning for this region. Results indicate that the Cerrado river basins contains 116 (30%) of Brazil's large hydroelectric plants and 352 (36%) of its small hydroelectric plants. Moreover, these plants spurred significant land use changes within a 5-km buffer of the dams, with over 2255 km² of native vegetation cleared by 2000 and an additional 379 km² in the ensuing 20 years, could reach ~1000 km². Based on the historical anthropization process in the Brazilian savannas, we expect new crops, pastures, and urban equipment to be incorporated into this landscape, with different impact loads. [ABSTRACT FROM AUTHOR]