WWF publishes research on world river maps

Dams and reservoirs have significantly reduced the benefits of healthy rivers for humans and nature.

The latest study on the connection status of rivers by 34 scientists from McGill University, WWF and other research organizations has just published in the scientific journal Nature (Nature) on 9/5 for See, out of the 246 longest rivers in the world, only 37% of them are free flowing.

The study is based on the results of the connection of rivers in the world with a total length of 12 million km. This is the world's first assessment of the location and extent of rivers that are free to flow on Earth.

Pak Beng hydroelectric dam built on the Mekong.(Source: Pak Beng Hydropower project).

There are only 21 out of 91 rivers in the world, with a length of more than 1,000km and flowing into the sea, still remain directly connected from the watershed to the ocean. Of these, the downstream part of the Mekong River, including Southern Laos, Thailand, Cambodia and Vietnam, remains free. The Mekong, Irrawaddy and Salween are threatened by infrastructure developments in the upper Mekong which are threatened by the huge Sambor dam project and the smaller but equally worrying Stung Treng dam project. .

Dams and reservoirs are the leading causes of disconnection of rivers in the world. The study estimates that there are currently more than 60,000 large dams in the world with more than 3,700 hydroelectric dams being planned or built. They are often planned and built at the individual project level making it difficult to assess the actual impact across the basin or region.

Mr. Michele Thieme, a research scientist of WWF and co-author said, this is the first map that allows us to prioritize and protect the free flowing rivers in the world because they are the source. live for wild animals and humans. Rivers provide a variety of resources but they are often undervalued and not valued. "Decision makers need to consider the whole value of rivers when planning infrastructure."

Healthy rivers enrich the fish resources, help improve food security for millions of people, build up silt to help the plains not sink under sea level, mitigate the impact of floods and droughts. prevent loss of infrastructure and erosion, and support the wealth of biodiversity. The connection of rivers, when disconnected, will lead to a decline or even loss of the value of this essential ecosystem.