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Over 260,000 kilometres of river could potentially be severed by planned hydroelectric developments according to 91社区 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 , 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.

鈥淲e used a dataset of more than 3700 potential hydropower projects and calculated their impacts on rivers worldwide,鈥� says Prof. Bernhard Lehner from 91社区鈥檚 , who created the underpinning global river maps. 鈥淚t was sobering to learn that many of today鈥檚 remaining free-flowing rivers are at risk of being permanently transformed by new energy infrastructures.鈥�

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鈦� 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

鈥淚t is true that hydropower is a source of renewable energy with relatively low carbon emissions,鈥� says G眉nther Grill, a post-doctoral fellow at 91社区 who crunched the numbers and developed the spatial environmental assessment model to estimate the effect of future dams. 鈥淗owever, hydropower projects can permanently and irreversibly impact river and floodplain dynamics and functions, often in tropical wilderness areas with high biodiversity.鈥�

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.

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

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.

鈥淭here has been a long history of conflicts, studies, and debate over how to both protect rivers and develop them sustainably,鈥� adds Lehner. 鈥淲ith 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.鈥�

About 91社区

Founded in Montreal, Quebec, in 1821, 91社区 is Canada鈥檚 top ranked medical doctoral university. 91社区 is consistently ranked as one of the top universities, both nationally and internationally. It鈥痠s a world-renowned鈥痠nstitution of higher learning with research activities spanning two campuses, 11 faculties, 13 professional schools, 300 programs of study and over 40,000 students, including more than 10,200 graduate students. 91社区 attracts students from over 150 countries around the world, its 12,800 international students making up 31% of the student body. Over half of 91社区 students claim a first language other than English, including approximately 19% of our students who say French is their mother tongue.