Algorithm optimizes trade-offs in Amazonian hydropower expansion

A new computational approach reveals opportunities for more sustainable hydropower development in the Amazon – the Earth’s largest and most biodiverse river basin, researchers report. Hydropower expansion is rapidly growing in many parts of the world and will likely play an important role in global efforts to achieve net-zero emissions. However, the placement, size, and number of dams within a river basin network can have enormous consequences for not only electricity generation, but also for the environment and the crucial ecosystem services these river basins provide. Despite this, the myriad impacts an individual dam can have at the whole-basin scale are difficult to understand and are thus rarely considered, especially when rivers span international boundaries. Leveraging advances in computational modeling, Alexander Flecker and colleagues developed a multiobjective optimization framework to evaluate the complex trade-offs between hydropower capacity, its impact, and a suite of environmental criteria, including river flow, sediment transport, river connectivity, and fish biodiversity, all of which encompass core river ecosystem services. Using their approach, Flecker et al. show that simultaneous consideration of these criteria when coordinating the size and location of dams minimizes their environmental impacts while still achieving energy production goals. The authors also show that the uncoordinated dam-by-dam expansion that has characterized hydropower expansion in the Amazon to date has largely resulted in environmental damage, particularly in terms of threatened fish diversity. “Science alone cannot provide an answer to whether expanding hydropower is the best way to sustainably support the sharply increasing global energy demand,” write Gordon Holtgrieve and Mauricio Arias in a related Perspective. “It can, however, provide tools like the one presented by Flecker et al. that make the best information and technology available to identify trade-offs, highlight options, and facilitate policy discussions that are critically needed not only in the Amazon but also in river basins around the world facing similar sustainable development dilemmas.”