Lake Chad: Shrinking Beauty

By Tom Yulsman | October 20, 2013 11:46 pm
Sunlight glints from the surface of Lake Chad in West Africa. Astronaut Karen L. Nyberg took the photo Oct. 17 from her perch on the International Space Station. (Photo: Karen L. Nyberg/NASA)

Sunlight glints from the surface of Lake Chad in West Africa, as seen from the International Space Station on Oct. 17. (Photo: Karen L. Nyberg/NASA)

Lake Chad once was a giant — the sixth largest lake in the world. But in the last 40 or so years it has shrunk by more than 90 percent in area, thanks to persistent droughts and increasing withdrawals of water for irrigation.

In Karen Nyberg’s photograph above, shot from the International Space Station on October 17, what’s left of the lake is illuminated by sunlight. Around it, and to the northwest, are ripples indicative of sand dunes — where water once was. And if you look closely toward the upper left, you can see smoke plumes — perhaps fires set by farmers.

I think Nyberg’s photo is a beautiful and bittersweet piece of Earth art.

Here’s what the lake looked like to the crew of Apollo-7 in October 1968:

Lake Chad as photographed from orbit by a member of the Apollo 7 crew in October, 1968. (Photo: NASA Earth Sciences and Image Analysis Laboratory http://eol.jsc.nasa.gov/)

Lake Chad as photographed from orbit by a member of the Apollo 7 crew in October, 1968. (Photo: NASA Earth Sciences and Image Analysis Laboratory )

The lake sits in the world’s largest endorheic basin. That wonderful scientific word, derived from the Ancient Greek ἔνδον, éndon, “within” and ῥεῖν, rheîn, “to flow,” means a drainage basin with no outflow.

Beginning in the 1960s, Lake Chad, then about 22,000 square kilometers in size, began shrinking. By the 1970s, it had split in two. Severe drought was part of the story. And so was a shallow ridge that ran under the lake, separating its northern and southern portions.

By the 1980s, the area of Lake Chad had shrunk to just 300 square kilometers. At that point, its northern portion went completely dry. You can see that portion of the lakebed in the northwest quadrant of the photograph.

There was a break in drought conditions during the 1990s. In the following map charting the fate of Lake Chad, you can see the reappearance of part of the northern portion in 1997:

By 2001, Lake Chad was a shadow of its former self. (Map: GRID-Arendal)

By 2001, Lake Chad was a shadow of its former self. (Map: GRID-Arendal)

Recent research shows that were it not for withdrawals of water for irrigation and other uses — some 30 million people rely on it for their livelihoods — the northern and southern portions would have actually merged in 1999. But since the 1990s, drought conditions have returned, eliminating the water to the north.

For the lake to recover to its 1963 size, an extra 26 cubic kilometers of water would have to flow back in every year for a decade. I wouldn’t be on that happening.

  • jh

    Is there some reason to believe 1963 is a baseline year? Should be relatively easy to find paleoshorelines beyond the 1963 lake margins if there are any.

    I presume someone has cored the area and developed a late-ish Holocene geologic history of the lake extent? What would the lake size be today without any withdrawals post 1963? I presume lake levels are also influenced by regional groundwater withdrawals? Is that factored in to the recent research on withdrawals?

  • Dominick Mezzapesa

    wow not one word of climate change…great job you actually told the truth about why the lake is shrinking

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ImaGeo

ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.

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