Reducing negative impacts of Amazon hydropower expansion on people and
nature
New computational tool can guide sustainable dam siting to protect
ecosystem services
Date:
February 17, 2022
Source:
Cary Institute of Ecosystem Studies
Summary:
Rapid hydroelectric dam expansion in the Amazon poses a serious
threat to Earth's largest and most biodiverse river basin. There
are 158 dams in the Amazon River basin, with another 351 proposed;
these projects are typically assessed individually, with little
coordinated planning. A new study provides a computational approach
for evaluating basin-level tradeoffs between hydropower and
ecosystem services, with the goal of guiding sustainable dam siting.
FULL STORY ========================================================================== Rapid hydroelectric dam expansion in the Amazon poses a serious threat
to Earth's largest and most biodiverse river basin. There are 158 dams
in the Amazon River basin, with another 351 proposed; these projects
are typically assessed individually, with little coordinated planning. A
new study, published today in Science, provides the first computational approach for evaluating basin-level tradeoffs between hydropower and
ecosystem services, with the goal of guiding sustainable dam siting.
========================================================================== Coauthor Stephen Hamilton, an ecosystem ecologist at Cary Institute
of Ecosystem Studies explains, "Continued hydropower development
in the Amazon is inevitable. So how can that proceed in a way that
optimizes energy output at the lowest environmental cost? The answer
comes in selecting projects strategically, taking into account multiple environmental criteria that have thus far been too difficult to account
for simultaneously in planning large numbers of potential projects."
Hamilton was part of an interdisciplinary team of environmental and computational experts who developed 'Amazon EcoVistas', a novel framework
to analyze proposed dam projects collectively -- both for their energy generation, as well as their impacts on the environment. They analyzed
five environmental criteria: river flow, river connectivity, sediment transport, fish biodiversity, and greenhouse gas emissions. Their tool
uses artificial intelligence and high-performance computing to identify hydroelectric dam portfolios that meet energy production goals with the
least environmental harm.
"Our tool allows us to evaluate hydroelectric projects for their
collective impacts to nature and people on the scale of the entire
watershed -- a rare, yet critical approach, since the Amazon River and
its tributaries flow through multiple countries with diverse topography," explains coauthor Rafael Almeida, a former visiting graduate student at
Cary who is currently an Assistant Professor at the University of Texas,
Rio Grande Valley. The tool can also screen out particularly harmful
projects, with Almeida adding, "Fragmentation of river systems, blockage
of fish migrations, trapping of sediment, and emission of methane are
all worsened by the absence of basin-wide planning." Almeida notes that
the environmental criteria evaluated have social values too.
Dams block sediments needed to fertilize agricultural crops growing
in the floodplain. Fishery degradation threatens an important source
of food and income, and river fragmentation disrupts transportation of
people and goods.
Running the 'Amazon EcoVistas' algorithm on the 158 existing and 351
proposed dams created scenarios based on all possible combinations of
these projects.
This allows it to determine the 'Pareto-optimal frontier' -- or
combination of hydropower projects that minimizes negative environmental effects for any given level of aggregate hydropower output. This process
is extremely computationally intensive; between the 509 total projects,
there are 2509(or ~10153) possible combinations -- with six dimensions
(energy output + the five environmental criteria) evaluated for each.
Lead author Alexander Flecker, Professor in the Department of Ecology
and Evolutionary Biology at Cornell University, says, "All decisions
around dam siting involve complex tradeoffs. The Pareto-optimal frontier provides a clear way to evaluate those tradeoffs as we seek to balance
energy production and diverse environmental consequences." For example,
dams in steep Andean valleys of upper Amazon rivers create smaller
reservoirs, and thus inundate less land and emit less methane. Dams built higher in the river system are also less disruptive for fish that need
to migrate long distances, while dams built lower in the system block
fish headed to upstream reaches of the river. However, Andean dams trap mountain sediments needed to nourish downstream ecosystems and maintain floodplains important to people and wildlife. And dams in steep valleys
are more likely to store water at higher flows, thereby creating more disruptive alterations to flows downstream.
Flecker continues, "There's no one-size-fits-all solution to minimize
negative environmental impacts of dam construction. But the most damaging impacts can be averted by weighing the various ecological and social
costs of different combinations of projects. Our novel computational
framework is the first to make this kind of evaluation possible on such
a vast basin-wide scale." "Applying our method to existing dams in the
Amazon shows how a lack of coordinated planning to date has resulted in projects that are collectively more harmful than would have been the
case had alternative, strategically selected portfolios of dams been
built," Almeida explains. "This is true for all five criteria that
we evaluated. Planning across borders would benefit all countries in
the region -- both in terms of meeting energy needs and facilitating
better environmental outcomes." By identifying opportunities for more sustainable hydropower development, 'Amazon EcoVistas' could prove
useful to energy planners, decision makers, and researchers working
to implement strategic, whole-basin dam planning. It could also help
evaluate priorities for dam removal in regions with aging dams such as
North America and Europe.
Hamilton concludes, "Hydroelectric energy planning typically happens
on a national basis, even though electricity is exported across
borders. Our evaluations demonstrate that coordinated whole-basin
planning can reduce environmental impacts while optimizing
energy production and maintaining crucial ecosystem services."
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Cary_Institute_of_Ecosystem_Studies. Note: Content may be edited for
style and length.
========================================================================== Related Multimedia:
* Map_and_images_of_hydropower_in_the_Amazon ========================================================================== Journal Reference:
1. Alexander S. Flecker, Qinru Shi, Rafael M. Almeida, He'ctor
Angarita,
Jonathan M. Gomes-Selman, Roosevelt Garci'a-Villacorta, Suresh
A. Sethi, Steven A. Thomas, N. LeRoy Poff, Bruce R. Forsberg,
Sebastian A.
Heilpern, Stephen K. Hamilton, Jorge D. Abad, Elizabeth P. Anderson,
Nathan Barros, Isabel Carolina Bernal, Richard Bernstein, Carlos M.
Can~as, Olivier Dangles, Andrea C. Encalada, Ayan S. Fleischmann,
Michael Goulding, Jonathan Higgins, Ce'line Je'ze'quel, Erin
I. Larson, Peter B.
McIntyre, John M. Melack, Mariana Montoya, Thierry Oberdorff,
Rodrigo Paiva, Guillaume Perez, Brendan H. Rappazzo, Scott
Steinschneider, Sandra Torres, Mariana Varese, M. Todd
Walter, Xiaojian Wu, Yexiang Xue, Xavier E. Zapata-Ri'os,
Carla P. Gomes. Reducing adverse impacts of Amazon hydropower
expansion. Science, 2022; 375 (6582): 753 DOI: 10.1126/
science.abj4017 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/02/220217141314.htm
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