• Reducing negative impacts of Amazon hydr

    From ScienceDaily@1:317/3 to All on Thu Feb 17 21:30:44 2022
    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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    ========================================================================== 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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