Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Ancient River System Flowed Under Sahara Desert (It Would Rank 12th largest Drainage Basin on Earth Today)

Science
Ancient River System Flowed Under Sahara Desert (It Would Rank 12th largest Drainage Basin on Earth Today)

Researchers have discovered the remains of a vast ancient river system that ran through what is known today as the Sahara Desert. The river system was so vast that if it were still flowing today, it would be ranked as the 12th largest drainage basin on Earth, say the researchers in their report published in Nature Communications on Tuesday.

Radar images reveal ancient rivers once flowed through the Sahara Desert. Photo credit: Philippe Paillou

Using radar images taken from a Japanese Earth observation satellite, researchers found ancient river beds running from the middle of the Sahara to the Mauritanian coast in West Africa, which appear to have originated in the Atlas Mountains to the north and Hoggar Mountains to the east.

This isn't the first time someone has suggested the Sahara was once "wet and humid" and, in fact, teeming with life. In 1957, an expedition led by French ethnologist Henri Lhote turned up cave paintings of giraffes and elephants. Since then, scientists have postulated that the Sahara has alternated between wet and dry periods during the last 300,000 years. As late as 7,000 years ago, "cattle, sheep and goats roamed over green savanna," says Livescience.

This map shows the present-day river networks of northern and central Africa, along with the ancient Tamanrasett River. Photo credit: Skonieczny et al.

IFLScience explains how we now know that water once flowed through this extremely arid climate:

The possibility that a river system once existed in the region was first hinted at around a decade ago, following the discovery of fine river sediment and a deep underwater canyon carved into the continental shelf off the coast of Mauritania. However, direct evidence needed to confirm this was lacking. This time around, the scientists used orbital radar satellite imagery, which allowed them to take images of the geology of the Sahara meters below the sandy surface using microwaves. From this data, the scientists could see the ancient riverbeds of the waterway, which incredibly matched up with the canyon off the coast.

It’s estimated that the river has been periodically flowing during what are called the African humid periods (AHPs), the last of which ended around 5,000 years ago when the lush, wet and humid Sahara which teemed with animals and life, turned into the dry, dusty place we know today. These switches between the wet and dry periods are estimated to occur every 20,000 years or so, as the Earth wobbles on its axis. Whether or not the ancient river beneath the desert will flow again during the next AHP is difficult to determine, however, as climate change is currently disrupting weather patterns, and making things harder to predict.

Russell Wynn at the National Oceanography Center in the UK was among the researchers who found evidence of an ancient river system more than a decade ago. He was not involved in this study, but he told the Guardian, “It’s a great geological detective story and it confirms more directly what we had expected. This is more compelling evidence that in the past there was a very big river system feeding into this canyon,” said Wynn. “It tells us that as recently as 5,000 to 6,000 years ago, the Sahara desert was a very vibrant, active river system.”

Today, the Sahelian zone south of the Sahara Desert is under threat from desertification. Nearly 75 percent of Africa’s drylands are degraded "with fast-growing populations trying to eke out a living by farming or grazing herds on ever less productive land," says Janet Larsen of the Earth Policy Institute. "Desertification is particularly acute in Burkina Faso, Chad and Niger, as well as in Nigeria, Africa’s most populous country, where an estimated 868,000 acres are lost to desert each year."

YOU MIGHT ALSO LIKE

Stunning Images of Earth, Delivered Daily by NASA

Breathtaking NASA Video Shows the Sun Like You’ve Never Seen It Before

What’s Going on in Antarctica? Is the Ice Melting or Growing?

Find Out What Humans Will Look Like in 1,000 Years

Coast Guard members work to clean an oil spill impacting Delaware beaches. U.S. Coast Guard District 5

Environmental officials and members of the U.S. Coast Guard are racing to clean up a mysterious oil spill that has spread to 11 miles of Delaware coastline.

Read More Show Less

EcoWatch Daily Newsletter

What happened to all that plastic you've put in the recycling bin over the years? Halfpoint / Getty Images

By Dr. Kate Raynes-Goldie

Of all the plastic we've ever produced, only 9% has been recycled. So what happened to all that plastic you've put in the recycling bin over the years?

Read More Show Less

Trending

Plain Naturals offers a wide variety of CBD products including oils, creams and gummies.

Plain Naturals is making waves in the CBD space with a new product line for retail customers looking for high potency CBD products at industry-low prices.

Read More Show Less
Donald Trump and Joe Biden arrive onstage for the final presidential debate at Belmont University in Nashville, Tennessee, on Oct. 22, 2020. JIM WATSON / AFP via Getty Images

Towards the end of the final presidential debate of the 2020 election season, the moderator asked both candidates how they would address both the climate crisis and job growth, leading to a nearly 12-minute discussion where Donald Trump did not acknowledge that the climate is changing and Joe Biden called the climate crisis an existential threat.

Read More Show Less
What will happen to all these batteries once they wear out? Ronny Hartmann / AFP / Getty Images

By Zheng Chen and Darren H. S. Tan

As concern mounts over the impacts of climate change, many experts are calling for greater use of electricity as a substitute for fossil fuels. Powered by advancements in battery technology, the number of plug-in hybrid and electric vehicles on U.S. roads is increasing. And utilities are generating a growing share of their power from renewable fuels, supported by large-scale battery storage systems.

Read More Show Less

Support Ecowatch