Just one half of world’s longest rivers run free, finds report

Only 37% of the world’s longest rivers remain free-flowing, with severe environmental degradation caused by extensive damming and climate change, a new report from Canada’s McGill University has concluded.

The report examined the impact of the world’s 60,000 dams on waterways around the globe, finding that 63% of the world’s 246 longest rivers are dammed.

The report also identifies climate change as a growing threat to river health, both from direct impacts and the extensive damming as a result of hydropower energy production.

“The world’s rivers form an intricate network with vital links to land, groundwater, and the atmosphere,’’ said lead author Günther Grill, a postdoctoral researcher in McGill’s Department of Geography.

‘’Free-flowing rivers are important for humans and the environment alike, yet economic development around the world is making them increasingly rare.”

A team of 34 international researchers from McGill University, World Wildlife Fund (WWF), and other institutions assessed the connectivity status of 12 million kilometres of rivers worldwide, providing the first ever global assessment of the location and extent of the planet’s remaining free-flowing rivers.

Among other findings, the researchers determined only 21 of the world's 91 rivers longer than 1,000 km that originally flowed to the ocean still retain a direct connection from source to sea. The planet’s remaining free-flowing rivers are largely restricted to remote regions of the Arctic, the Amazon Basin, and the Congo Basin.

The full report, published in the journal Nature, can be accessed here

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