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[SÃO PAULO] Small hydropower dams in the Amazon are being built without consideration of their harmful effects on the river system, including damage to the livelihoods of indigenous people, researchers have concluded.

Evidence-based environmental assessments are needed to mitigate this damage, the scale of which is currently unknown because of deficient policies and planning instruments, according to the team of researchers, who analysed the impacts of small dams in the Amazon basin, the largest and most complex fluvial system on Earth.

Such mini dam projects may threaten ecosystem services, biodiversity conservation, and the livelihoods of indigenous and traditional communities who depend on these for fishing, the researchers found.

“We do not know exactly what would be the impacts of all these endeavours in the Amazon basin, and yet important decisions are being made. It is scary,”

María Elena López, Federal University of Pará, Brazil

The team analysed environmental licensing reports relating to small hydropower dam projects in the Cupari river — an affluent of the Tapajós river connected to indigenous lands, archaeological sites and protected areas of Brazil. They found that the country does not have policies or instruments capable of properly assessing the potential environmental and social impacts linked to the expansion of small dam projects in the Amazon.

These failings make it difficult to back up the decision-making process and produce ­­policies that protect human and environmental rights, the authors of the study published in Energy Policy warn.

Despite this, incentives and policy regulations have contributed to a five-fold increase in the number of small dams in the past 20 years in Brazil, with 87 currently operating and 256 registered in the Amazon basin.

The Tapajós basin is set in a little-known biodiversity hot spot and is considered one of the most important areas of the Amazon when it comes to diversity and endemism of fish and bird species.

Eight hydropower projects are planned for the Cupari river: four small hydropower dams to the east and three others, plus one larger dam, to the west. It is expected that these complexes will flood an area of 20 square kilometres and generate 157.5 megawatts across three municipalities. However, there is no start date for construction yet, as the project is pending approval by environmental authorities.

Researchers argue that although two Environmental Impact Assessments (EIAs) were produced during the project licensing process, they neglected the cascade effects linked to the construction of small hydroelectric plants in that region.

EIAs are preventive instruments used to ensure that the possible impacts of a project that could cause environmental damage are analysed, and that those impacts are taken into account in the approval process.

Simone Athayde, a biologist at the University of Florida’s Center for Latin American Studies, in the United States, and lead author of the study, said: “The EIAs have not assessed the potential impacts on the Tapajós National Forest, a federal protected area of 549,257 hectares, occupied by traditional riverside communities, that hosts a rich diversity of fish, mammals and birds.
 
“Even though EIAs estimate the impact of small dam building on fish populations, they fail to report the social consequences of these impacts on fish stocks for indigenous and traditional communities nearby. In this sense, the licensing process for the Cupari complex contradicts Brazilian national policies, as well as international treaties for the defence of human rights.” María Elena López, a biochemist at the Federal University of Pará’s institute of biological sciences, believes that the impact in Cupari will not limited to this region. “They may have repercussions all along the Amazon rivers,” she said.

López noted that some studies have shown that dams are capable of increasing the concentration of toxic metals such as mercury, contaminating fish which can migrate for many miles and affect the populations that consume them.

“We do not know exactly what the effect of all these initiatives will be in the Amazon basin, and yet important decisions are being made. It is scary,” she said. “If decision-makers want these studies to become truly useful tools, they must seek an integrated view of the cumulative effects of these infrastructure projects across the entire Amazon river system.”

This piece was originally produced by SciDev.Net’s Latin America and Caribbean edition.

The study published in Energy Policy is funded by FAPESP, a donor of SciDev.Net.