Finding Water from Space: How One Geologist Is Using Satellite Technology to Help in Drought-Striken Areas

The Land Cruiser rattles and bumps down a stripe of rutted dirt carving through the brush in this remote corner of southern Angola. Half a mile to the west, the tranquil blue Atlantic glimmers in the African sun. To the east, miles of spiky desert grass fade away to a range of sere mountains. The last village lies miles behind us, the next miles ahead.

In the front seat, Alain Gachet, a plump, boyish 58-year-old, his thick crest of silver hair crammed under a leather Indiana Jones hat, is focused intently on the laptop balanced on his knees. The computer is plugged into a tiny GPS unit set on the dashboard. On the screen, a thin yellow line tracking our progress creeps forward over a map stippled with thousands of differently colored squares.

"Stop here!" Gachet cries suddenly.

The driver brakes in the middle of the track. By the time three South African drillers and I extricate ourselves from the cramped vehicle, Gachet has bounded out, scrambled over a hillock and found a low, clear patch of sandy yellow soil.

"Right here, Freddy," Gachet requests in French-accented English.

Freddy Chambers, the beefy lead driller whose thick salt-and-pepper hair and mustache lend him a passing resemblance to Saddam Hussein, drives a shovel into the earth. Gachet practically vibrates with excitement as he watches. About 2 feet down, muddy gray water starts bubbling into the hole. Both men's faces split into grins.

Gachet fills an empty juice bottle with the cloudy liquid, strains it through a portable filter and drinks. "Fresh water," he says and bursts out laughing.

It's an extraordinary find, not only because the area is so dry, but because underground water this close to the sea would normally be too salty to drink. Gachet knew there would be fresh water in this spot, though; messages from outer space told him so.

Finding more fresh water is one of the paramount challenges of the 21st century. Nearly one-third of the human race lacks reliable access to clean water, according to the International Water Management Institute. Some 3 million people -- most of them children -- die every year from diseases spread by contaminated water. A 2007 report by the U.N. Environment Program predicts that by 2025, if population growth and environmental degradation continue apace, 1.8 billion people will live in countries with "absolute water scarcity."

A former oil industry geologist, Gachet has developed a path-breaking, high-tech system that could help slake that growing thirst. The key: using satellites high above the Earth's surface to see what's underneath it.

By combining terabytes of space-based photographic imagery, ground-penetrating radar and topographic data -- much of which has only recently become available -- Gachet creates multispectral maps that are proving excellent guides for finding undiscovered underground aquatic resources. At the height of the Darfur crisis, the United Nations called on Gachet to help find sustainable locations for camps in Chad that now house thousands of refugees. It was the first time such technology had been used in a humanitarian emergency. "Gachet's work was an extremely important contribution at a time when it was not sure that [the U.N.] would be able to provide water for the long term for all refugees," says Marc-Andre Bunzli, a former U.N. official who worked with Gachet in Chad. Since then, Gachet has located water in Darfur itself, as well as in parts of Afghanistan, Iraq and Eritrea.

I joined Gachet last summer for the kickoff of a new project. Joint Aid Management, a South Africa-based humanitarian group, recently began a campaign to provide food and water to some 450 schools scattered over hundreds of miles in war-blasted Angola. Because it costs an average of $10,000 to bore a hole for a well, the group has a major incentive to increase its hit rate. Joint Aid Management brought in Gachet to help them figure out where to dig.