Andes dams twice as numerous as thought are fragmenting the Amazon

The Marañón River flows though the Peruvian Andes, and is a major Amazon River tributary. The Peruvian government is planning to build several major dams on the river, though the projects are fiercely opposed by many local riverine communities. Photo by Gato Montes on Wikimedia CC-BY 3.0 The scale of hydroelectric development in the Andean Amazon is far more extensive than previously thought, with numerous headwater dams fragmenting river habitats, disrupting natural systems, and affecting the lives and livelihoods of 30 million downstream Amazon basin inhabitants, according to a new study published in Science Advances. If proposed dams in the region go ahead, sediment transport from the Andes to the Amazon floodplains will cease and migratory routes of freshwater fish will be blocked, threatening food security for downstream communities. An international team of researchers led by Elizabeth Anderson, a freshwater ecologist at Florida International University in Miami, used satellite imagery to verify reported locations of existing dams in the Amazonian Andes of Columbia, Ecuador, Peru and Bolivia, and to quantify their impact on river connectivity. The scientists identified 142 dams currently in operation or under construction – twice the number previously estimated. This study represents “the most detailed accounting of dams in the Andean region,” says Kirk Winemiller, an aquatic ecologist at Texas A&M University, who was not involved in the study. The team also included the impact of proposed dams in their model – an additional 160 projects – and found that they would further reduce connectivity on five…

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