Over 260,000 kilometers of rivers at risk due to proposed hydro dams
Dams and reservoirs are the leading contributors to future loss of connectivity in free-flowing rivers around the world

Date:
August 12, 2021
Source:
McGill University
Summary:
Over 260,000 kilometers of river could potentially be severed by
planned hydroelectric developments according to researchers. The
Amazon, the Congo, and the Irrawaddy are just a few of the rivers
at risk of losing their free-flowing status if the proposed
construction of new hydro power dams takes place. The study showed
that planned dams and reservoirs are leading contributors to the
decline of free-flowing rivers around the world. It also provides
a comprehensive list of science-based solutions to minimize the
impacts of hydro power development in rivers.



FULL STORY ==========================================================================
Over 260,000 kilometres of river could potentially be severed by planned hydroelectric developments according to McGill University researchers. The Amazon, the Congo, and the Irrawaddy are just a few of the rivers at risk
of losing their free-flowing status if the proposed construction of new hydropower dams takes place. The study, led by World Wildlife Fund and published recently in Global Sustainability, showed that planned dams and reservoirs are leading contributors to the decline of free-flowing rivers around the world. It also provides a comprehensive list of science-based solutions to minimize the impacts of hydropower development in rivers.


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"We used a dataset of more than 3700 potential hydropower projects and calculated their impacts on rivers worldwide," says Prof. Bernhard
Lehner from McGill University's Global HydroLab, who created the
underpinning global river maps. "It was sobering to learn that many of
today's remaining free-flowing rivers are at risk of being permanently transformed by new energy infrastructures." Moreover, the study also
finds that all the proposed dams on free-flowing rivers would collectively generate less than 2% of the renewable energy needed by 2050 to keep
global temperature increase below 1.5? C -- a small contribution with potentially devastating consequences to the remaining free- flowing
rivers, and the people and wildlife that depend on them.

The researchers suggest that, as global leaders convene for a critical
round of UN climate and biodiversity summits this fall, policymakers must consider the tradeoffs between hydropower development and maintaining
healthy freshwater ecosystems.

Looking at the tradeoffs -- Hydropower development vs. environmental
costs "It is true that hydropower is a source of renewable energy with relatively low carbon emissions," says Gu"nther Grill, a post-doctoral
fellow at McGill who crunched the numbers and developed the spatial environmental assessment model to estimate the effect of future
dams. "However, hydropower projects can permanently and irreversibly
impact river and floodplain dynamics and functions, often in tropical wilderness areas with high biodiversity." The policy paper points to
the fact that connected and healthy rivers deliver diverse benefits that
are often overlooked: freshwater fish stocks that improve food security
for hundreds of millions of people; delivery of sediments that nourish agriculture and keep deltas above rising seas; and floodplains that help mitigate the impact of floods and support a wealth of biodiversity.

"When it comes to river health, climate change and biodiversity loss,
we can no longer afford to think of these as separate issues," says
Michele Thieme, lead freshwater scientist at World Wildlife Fund (WWF)
and lead author of the study.

"Rivers are powerful agents for keeping wildlife and communities healthy, especially in a warming climate, yet their ability to support life is threatened by hydropower dams in many parts of the world. The best policy solutions will be those that balance renewable energy needs with the many benefits of thriving freshwater ecosystems." Safeguarding free-flowing
rivers while meeting climate targets and energy needs In the paper,
the researchers have compiled a list of science-based policy solutions
to meeting climate targets and energy goals, while also safeguarding free-flowing rivers and their benefits to people and nature. These
solutions include avoiding river fragmentation by exploring alternative development options, such as non-hydropower renewable energy, like solar
and wind; minimizing impacts by siting dams in locations with fewer consequences on people and nature; restoring rivers through dam removal;
or offsetting the negative impacts of dams on one river by formally
protecting another, similar river.

"There has been a long history of conflicts, studies, and debate over how
to both protect rivers and develop them sustainably," adds Lehner. "With
a pause in new developments caused by the global pandemic, anticipated
further implementation of the Paris Agreement and high-level global
climate and biodiversity meetings in 2021, now is an opportune moment
to consider the current trajectory of development and policy options for reconciling dams with freshwater system health." The research was funded
in part by WWF in Washington, DC and by McGill University in Montreal,
Quebec, Canada.

========================================================================== Story Source: Materials provided by McGill_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. M.L. Thieme, D. Tickner, G. Grill, J.P. Carvallo, M. Goichot, J.

Hartmann, J. Higgins, B. Lehner, M. Mulligan, C. Nilsson,
K. Tockner, C.

Zarfl, J. Opperman. Navigating trade-offs between dams and
river conservation. Global Sustainability, 2021; 4 DOI:
10.1017/sus.2021.15 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210812123055.htm

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