Mapping the world’s free-flowing rivers

Abstract

Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.

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Affiliated Institutions

• The Nature Conservancy US
• University of Wisconsin–Madison US
• University of Tübingen DE
• Leibniz Institute of Freshwater Ecology and Inland Fisheries DE
• WWF-India IN
• Umeå University SE
• Stanford University US
• King's College London GB
• WWF-UK GB
• Pension Fund for Care and Well-Being NL
• McGill University CA
• World Wildlife Fund Canada CA
• WWF Germany DE
• University of Basel CH
• IHE Delft Institute for Water Education NL
• University of Washington US
• Conservation International US
• World Health Organization - Zambia ZM
• University of Nevada, Reno US
• World Wide Fund for Nature CH
• World Wildlife Fund US
• WWF Italia IT

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