Damn Dams: A choking hazard for Amazonia
A new report by WHRC scientists Marcia Macedo and Leandro Castello highlights hydroelectric dam projects in the Amazon as a key threat. The report, commissioned by the Living Amazon Initiative of the World Wildlife Fund, entitled, “State of the Amazon: Freshwater Connectivity and Ecosystem Health” reviews the current state of watershed ecosystem health and identifies key threats and opportunities for conservation across Amazonia. The report finds that planned hydroelectric dam projects will constrict every subwatershed and undermine the health of the entire Amazonian watershed.
The health of the Amazon watershed depends on annual flood cycles, which cause rivers to swell by as much as 20 meters each year. As river water overflows into the floodplains, rivers become connected to surrounding forests.
This annual flood pulse serves as a giant mixing bowl, transferring vital sediments and nutrients and providing a highway for fish migration. Dam projects sever these essential connections, increasingly fragmenting individual subwatersheds and undermining the health of the whole Amazon system.
Dams are not the only threat to watershed health.
The region continues to be at risk from deforestation, mining and hydrocarbon extraction, and climate changes
, all of which may change the annual flood pulse and river connectivity.
Economic pursuits tend to increase energy demand, which drives the construction of more hydroelectric dams in the region. But these cumulative impacts are often ignored in environmental policies governing dam construction. Environmental impact assessments only consider the effects of individual projects, making it virtually impossible
to achieve integrated watershed management. The Amazon Basin spans seven nations
, which is perhaps the biggest challenge to holistic watershed management. Healthy river systems depend on connectivity and do not respect political boundaries. In many cases, economic development activities in one country can incur environmental costs in another, yet there is not an overarching policy framework to help coordinate management activities across country boundaries.
Developing such a multinational framework is both the biggest challenge and the biggest opportunity for conserving Amazon freshwater ecosystems and supporting the productive fisheries and human populations that depend on them.http://bit.ly/1I3BQJehttp://whrc.org/news/newsletter/pdf/WHRC_Newsletter_May2015.pdf