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Endangered Deltas

   
Mackenzie River Delta (Image 1 of 12)

After flowing more than 1,000 miles through the Canadian wilderness, the Mackenzie River empties into the Beaufort Sea, forming an extensive delta ecosystem that’s home to grizzly bears, beluga whales and more than 100 species of migratory birds.

Photo © All Canada Photos / Alamy

   
Ord River Delta (Image 2 of 12)

Classified as a tide-dominated delta, the Ord River opens into the Cambridge Gulf in Western Australia. It boasts multiple species of mangroves and provides saltwater crocodile habitat.

Photo © Cultura RM / Alamy

   
Maggia River Delta (Image 3 of 12)

Even residents of a mountainous landlocked nation can get a day at the beach as the Maggia River forms a sandy delta at Lake Maggiore near Locarno, Switzerland.

Photo © imageBROKER / Alamy

   
Colorado River (Image 4 of 12)

The Colorado River has not regularly reached the Gulf of California since 1960, but efforts like the Sonoran Institute’s Colorado River Delta Program are working to restore this desert delta.

Photo © National Geographic Image Collection / Alamy

   
Sacramento-San Joaquin River Delta (Image 5 of 12)

The fertile soils of California’s 738,000-acre Sacramento–San Joaquin Delta support more than $500 million in annual agricultural productivity.

Photo © Aerial Archives / Alamy

   
Okavango Delta (Image 6 of 12)

On the edge of Botswana’s Kalahari Desert, cheetahs, giraffes and zebras all flourish in the world’s largest inland delta.

Photo © Hemis / Alamy

   
Neretva Delta (Image 7 of 12)

Although much of the Neretva Delta in southern Croatia has been converted to agricultural land, protected areas for birds, fish and plants cover 13 percent of the region.

Photo © LianeM / Alamy

   
Parnaíba River Delta (Image 8 of 12)

Located in northeastern Brazil, the large, open sea Parnaíba River Delta boasts more than 80 islands, with mangroves, sand dunes and beaches dotting this federally protected landscape.

Photo © BrazilPhotos.com / Alamy

   
Tiroler Achen Delta (Image 9 of 12)

As the Tiroler Achen — a mountain river in southern Germany — flows into Chiemsee lake in Bavaria, it forms the Achendelta, a 3,000-acre nature reserve that is home to more than 260 bird species.

Photo © LOOK Die Bildagentur der Fotografen GmbH / Alamy

   
Pearl River Delta (Image 10 of 12)

With cities like Guangzhou and Shenzhen, the Chinese government is implementing plans to merge communities in the Pearl River Delta into a megacity of more than 42 million people.

Photo © Martin Harvey / Alamy

   
Nile Delta (Image 11 of 12)

The Nile Delta supports agriculture and around half of Egypt’s population as the world’s longest river empties into the Mediterranean Sea.

Photo © RGB Ventures / SuperStock / Alamy

   
Mekong Delta (Image 12 of 12)

Sea-level rise threatens to flood 60 percent or more of the Mekong Delta, which produces almost half of Vietnam’s rice supply.

Photo © Robert Harding World Imagery / Alamy

 

In many ways, deltas are a river system’s “grand finale.” After meandering hundreds or thousands of miles, a river’s velocity decreases as it enters a larger water body, depositing nutrient-rich sediment and forming a vast network of waterways. 

These diverse deltaic wetlands — found from the Arctic Ocean to the Mediterranean Sea to the Kalahari Desert in Botswana — are home to innumerable plant and animal species. Fertile delta soils form some of the most agriculturally productive landscapes in the world, including the Nile Delta in Egypt, the Sacramento–San Joaquin Delta in California and the Mekong Delta in Vietnam. Given their economic and ecological significance, half a billion people worldwide call river deltas home.

But deltas are disappearing. Human alterations to river systems are eroding deltas and starving them of sediment while sea-level rise threatens to turn deltas around the world over to the ocean. Saving these unique and diverse ecosystems is becoming a priority among researchers, engineers and government officials alike. View Ensia homepage

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