MIT Technology Review: How do cow herders spot water in the Sahara? With satellites, of course.

Climate change makes it even harder to find water on the edge of the Sahara. Now herders in Mali rely on images from space to direct them to the nearest watering hole.



This story first appeared in MIT Technology Review.

For most of his 50 years, Abdoul Ag Alwaly, a cattle herder in northern Mali, used the same way of finding water for his cows. He would pay a motorcyclist or camel driver to roam the desert surrounding the city of Gao and check the levels of scattered creeks and wells. The process was expensive, time-consuming, and risky—sometimes he’d march his herd for days only to find that he’d received a bad tip, or that another herd had gotten there first.

In recent years climate change has made the search even harder, Alwaly says. Where he lives, in the Sahel, the vast strip of arid scrubland south of the Sahara Desert, temperatures are rising faster than the global average, droughts are more frequent, and vegetation is scarcer. Erratic rainfall has made traditional watering holes unreliable. Animals frequently perish during the search, Alwaly says, and competition for water can easily turn violent.

So he’s trying a new approach. Over the last year, Alwaly, who leads a local union of livestock herders, has started to look for leads in satellite images. “With your phone and 25 francs”—about four US cents— “you’ll know, and can move with a lot more certainty,” he says.

Across the continent, rising temperatures and unpredictable rains are a serious threat to millions of small farmers and herders. Real-time, hyper-local satellite data can be used to detect early warning signs of drought and crop failure. As satellite imaging gets cheaper, more prolific, and higher in resolution, and the massive quantities of data it yields become easier for computers to manage and interpret, a growing number of private companies and nongovernmental organizations are finding ways to put it directly into the hands of people who deal with the effects of climate change every day.

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