Out of some 151 dams proposed for the Amazon river system, more than half will sever the connectivity between the Amazon lowlands and headwaters in the Andes mountains, according to the latest study. The unimpeded flow of the river over the past 10 million years is thought to have fuelled the extraordinary biodiversity of the Amazon ecosystem1.
The finding follows decisions to prioritize hydropower development in the countries that share the Amazon tributaries, including Bolivia, Columbia, Peru, Brazil and Ecuador. As many as 48 dams that produce more than two megawatts of power are already in place, and there are plans to triple that number by 2030. Peru, especially, is aggressively pursuing hydropower in cooperation with Brazil.
The study, published in the journal PLoS ONE2, is the first to evaluate the impact of all proposed dams on the six Amazon river basins across five countries, together with associated projects to construct road and power lines. Previous impact assessments focused only on individual projects and country-level impacts.
This kind of analysis has been needed for a long time to take a comprehensive view of the Amazon basin, says Robert Naiman, a river ecologist at the University of Washington in Seattle.