National Commentary

Nicholas F. Benton: On Irrigating The Sahel

In the cover story of the April 2008 edition of National Geographic magazine, “Africa’s Ragged Edge: Journey Into the Sahel,” author Paul Salopek, photographer Pascal Maitre and the editors do a terrific job introducing readers to perhaps the most important region of the world that no one, almost, has heard about.

The Sahara is known, the Sahel is not.

Yet the Sahel is perhaps the largest contiguous arable region on the planet, dwarfing the entire continental United States in scale. From coast to coast, from Dakar on the west to the Red Sea on the east, it is at least one-and-a-half times the width of the U.S. Presently, despite its dry and undeveloped condition, it is home to an estimated 55 million mostly poverty-stricken and ethno-politically divided people.

As the National Geographic article points out, the Sahel’s dimensions have shifted over the centuries due to the amount of rainfall. Just as the arable land in the U.S. plains can devolve from agriculturally-fertile to dust bowls, so it goes for the Sahel. The Sahara Desert can encroach on its land under drought conditions, or it can recede when there is rain. At one point a thousand years ago, much of it was fertile and lush, and in that era Timbuktu on the Niger River in modern Mali was the seat of a rich and powerful regime.

What the National Geographic article does not talk about is the potential and, indeed, the necessity to transform that region through large-scale water diversion projects. In fact, studies now relegated to obscurity were done by the French, who once dominated the region, on how to transfer water in huge quantities from the Congo River, one of the most powerful on the planet, into the Sahel specifically into the Lake Chad basin.

There is a single mountain range north of the Congo River that would have to be scaled by a water diversion effort, although for the largest portion of the trip, water would flow by gravity downhill to Lake Chad.

From Lake Chad, a network of canals would be built transferring large quantities of water onto the arable land far to the east and west. It is now known, for example, that a giant, ancient lake bed sits under modern day Darfur to the east, suggesting the capacity of that region to receive and hold large quantities of water for agricultural purposes.

It was exactly this kind of approach that turned the Central Valley of California into one of the world’s great breadbaskets over the first half of the 20th century. The Central Valley was itself once an ocean bottom and its similarity in appearance to whole regions of the Sahel can be seen in areas where the canals have not come to provide irrigation for intensive fruit and vegetable cultivation.

The Los Angles basin in Southern California was also developed by a similar means. Once dry and barely arable, it flourished once the Hoover Dam was built on the Colorado River in Nevada and water began being diverted. A basin once capable of supporting a few thousand people is now home to more than 12 million.

The critical importance of reviving the push for a large-scale water diversion project into the Sahel is defined not only from the standpoint of its impact on ending poverty, but also from the global warming perspective.

Waters as powerful as the Congo River’s that flow to the ocean without environmental impact do nothing to stem the current global warming trend that threatens to wreak monumental damage to the planet.

However, if that water can be put to the use of creating vegetation, resulting in a cooling of the atmosphere, then it can play a vital role in reversing global warming.

By irrigating the Sahel using water from the Congo River, resulting agricultural capability would not only feed the people there, and provide exports for the rest of the world, it would cause a shift in the atmosphere, precipitating patterns of rainfall that were not there before.

For an area as vast as the Sahel, this could have global atmospheric consequences in a way that could help cancel out warming trends globally. The double benefit from this approach seems hard to dispute.


A great new envisioning, investment and diplomatic effort would be required to pull this off, but then its success would be epochal for the entire planet. Who wants to get started?