Only one-third of the world’s very long rivers remain free-flowing
Researchers from Global HydroLAB and World Wildlife Fund led a team of 34 international researchers in the first ever global assessment of the location and extent of the planet’s remaining free-flowing rivers. The team assessed the connectivity status of 12 million kilometres of rivers worldwide. The study is published in Nature.
Among other findings, researchers determined only 21of 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.
Dams and reservoirs are the leading contributors to connectivity loss in global rivers. The study estimates there are around 60,000 large dams worldwide, and more than 3,700 hydropower dams are currently planned or under construction. They are often planned and built at the individual project level, making it difficult to assess their real impacts across an entire basin or region.
Free-flowing rivers provide crucial habitat for a host of animals, and support the survival of both people and nature around the world. Climate change will further threaten the health of rivers worldwide. Rising temperatures are already impacting flow patterns, water quality, and biodiversity.
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