The Amazon basin will suffer significant and irreversible environmental damage if hundreds of planned dams are constructed. The hydrophysical and ecological disturbances will impact the Amazon basin’s floodplains, estuary, and sediment plume. The benefits will not outweigh the costs.
These findings emerge from a multi-disciplinary and international collaboration of researchers drawn from 10 universities and research institutes, including Saïd Business School, University of Oxford. The study, published in the latest edition of Nature (Volume 546 Number 7658), the world’s top-ranked journal, analysed the impacts of 140 constructed and under-construction dams and the potential impact of 428 built and planned dams on the rivers of Amazon. The researchers developed a Dam Environmental Vulnerability Index (DEVI) which quantifies for the first time the regional and continental impacts of dams in the Amazon basin. The study found that if even a fraction of the planned dams are built there will be significant environmental consequences, with no existing technology capable of restoring the negative effects.
Edgardo M. Latrubesse, the lead author of the paper and a Professor at the Department of Geography and the Environment at University of Texas at Austin, says: ‘Whilst recent scientific reviews have considered the environmental impacts of damming Amazonian rivers, the assessments have only been in the vicinity of each dam. The effects of dams are large scale and affect huge areas of land and river systems in complex ways. There was a pressing need for a more systematic evaluation to inform decision making and consider alternatives to megaproject damming of the river systems, which is what we have attempted to do in this study.’
Dr Atif Ansar, Saïd Business School, University of Oxford, one of the authors and members of the multidisciplinary team comments: ‘Our previous work had shown that due to a systematic problem of cost and time overruns, the actual construction costs of large dams were too high to yield a positive return. Our previous analysis, however, had not accounted for the negative impacts on human society and the environment. With this contribution, our team shows that the negative environmental consequences of large dams are quantifiably significant and irreversible. Large dams are not only economically unviable but also environmentally detrimental’.
The paper concludes that contrary to current policy, the energy sector needs to be part of integrated Amazon-basin planning and management initiatives and that the medium term demands for electricity can be met without sacrificing Amazon fluvial and coastal ecosystems and economies.
Professor Bent Flyvbjerg, Saïd Business School, University of Oxford, fellow author of the study adds: ‘International collaborations among scientists and management scholars are rare. But this study shows the powerful contribution research teams can make by working across disciplines. This is an ongoing project, where the next aim is to consider the social displacement impacts of damming in addition to the environmental and economic factors we have previously studied. But so far we have demonstrated beyond reasonable doubt that the costs of dams outweigh the benefits.'
Dr Atif Ansar concludes: ’Advances in technology allow us to harness water resources by producing more modular and flexible projects that can be built and go online quicker, and are more easily adapted to social and environmental concerns. Evidence suggests that modular solutions including wind, solar, and on-site combined heat, cooling, and power plants provide compelling alternatives, both financially and environmentally.’