Few of the World’s Great Rivers Are Wild and Free

A scientific survey of the world’s longest rivers using aerial maps shows a majority of them are no longer able to complete a natural flow, unimpeded by human interference. This is true of the world’s most well-known great rivers, including the Amazon, Nile and Yangtze. Is this a bad thing?

Compared to coal-fired power plants, hydroelectric is without a doubt the way to go. It’s a renewable energy source that does not directly produce chemical byproducts or greenhouse gases. Obviously construction itself might involve emissions, and the clearing of trees has a carbon-negative effect. But compared to the ongoing damage of the dirtiest types of large-scale power generation, there’s a lot to be said for hydroelectric.

But every major infrastructure project has its environmental impact especially hydroelectric power plants. So let’s talk about it.

Recent studies have looked at the impact of damming in the Amazon river basin. Dams and reservoirs alter the original character of a region’s geography and ecology. The depth and flow speed of rivers change, which affects the types of animals that can thrive there. And of course, areas that are dammed become submerged, so ensuring that unique species and ecosystems are not in the flood zone is important when selecting a site.

One example of an affected species is the dorado, a fish who normally swims a great distance up the Amazon River to breed but is now being blocked by dams. Moreover, the disruption of the natural flow of sediment could have serious effects, including erosion that could further influence the geography and ecology of the river and its surrounding basin.

China’s massive Three Gorges Dam has also been the subject of interest for scientists, engineers and documentarians. Comparing the proliferation of smaller projects throughout the Amazon to the fewer, but larger projects in China might suggest something about which option is more sustainable.

Some might argue the negative impact of any hydroelectric project is so significant that it’s merely the best of the worst available options. But only a full environmental accounting of all options in a region can make a definitive judgment. It’s therefore an open question whether we might, for example, need to leave certain rivers alone entirely or build on rivers in a different, perhaps not-yet-invented way.

Renewable energy is not automatically sustainable. Understanding the geographical and ecological nature of the regions where these projects are situated will only become more important as hydroelectric aims to fill growing power needs of our large human population and as climate change makes regions more sensitive to human disruption. I’m a fan of hydroelectric, but the research on this is welcome and long overdue.

Photo credit: Le Grand Portage/Wikimedia Commons

41 comments

Leo Custer
Leo Cabout a month ago

Thank you for posting!

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heather g
heather gabout a month ago

The company Vane, in Brazil, has been urgently called to prevent another disastrous dam failure. Last time 200 people were killed.

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Ann B
Ann Babout a month ago

nothing is free anymore

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Marion Morin
Marion Morinabout a month ago

so few

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Sherry Kohn
Sherry Kohnabout a month ago

Noted

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Danuta W
Danuta Wabout a month ago

thanks for sharing

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Toni W
Toni Wabout a month ago

tyfs

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Toni W
Toni Wabout a month ago

tyfs

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Debbi W
Debbi Wabout a month ago

I'm against hydroelectric power blocking our rivers. It effect wildlife and their survival.

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David C
David Cabout a month ago

sadly noted

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