Boston University’s Center for Remote Sensing puts space-based sensors to work finding groundwater in the world’s deserts.
J. M. Berger
Last month, Boston researchers announced their discovery of evidence of a massive lake that existed more than 11,000 years ago in war-ravaged North Darfur. The researchers, with Boston University’s Center for Remote Sensing, say they’ve found signs of other dried-up lakes and rivers in Sudan and North Africa, using satellite radar imaging.
This work springs in large part from the vision of the center’s director, Farouk El-Baz. The Egyptian native wants to see the world’s deserts transformed into livable, peaceful, and prosperous places. The first step, he says, is to find groundwater by looking for signs of ancient lakes and rivers; groundwater usually remains where surface waters once flowed. The center has ongoing projects in the United Arab Emirates, Chad, Sudan, Egypt, and Libya, and is improving satellite-imaging techniques so that researchers can gather more detailed information about the land below.
Boston University’s Farouk El-Baz uses satellite imaging to find groundwater in the deserts of Africa and the Middle East. (Credit: Kalman Zabarsky, BU)
“We’re using advanced technologies and satellite images and space pictures and pixels, and you name it. And then we’re using this to find water for people who don’t have water,” says El-Baz. “Water is essential to life.”
Water hunter
Desert reclamation has been El-Baz’s lifelong passion. In the late 1970s, he advised the Egyptian government on which parts of the desert should be developed. He first developed his skills in satellite imaging in the late 1960s, when he helped guide the selection of lunar landing sites for the Apollo missions to the Moon.
El-Baz’s work has already paid off. His radar exploration of the Egyptian Sahara desert eventually resulted in the drilling of about 500 wells in the area known as Sharq Al Owaynat, starting in 1997, all of which are still pumping water today. About 100,000 acres of Saharan desert in this area have been cultivated. In his office, El-Baz keeps a jar of peanuts grown on one of the farms.
Groundwater discovered by satellite has made agricultural development possible at Sharq Al Owaynat, Egypt, in the Sahara Desert. (Source: Boston University’s Center for Remote Sensing)
Now he and his team are turning their attention to other parts of North Africa, including the Darfur region.
On the surface Darfur looks like a vast expanse of sand. But radar allows researchers to see ground that has been covered for millennia. Eman Ghoneim, a geologist with the BU center, found a 150-mile long ridge in satellite radar images. She soon realized it was only part of a tremendous shoreline. At its peak, the body of water was bigger than Lake Erie, meaning that a massive reservoir of groundwater almost certainly persists, she says.
Super satellites
In areas like Darfur, the fieldwork needed to follow up on such leads can be dangerous, even impossible. By improving the capabilities of space-based sensors, the center hopes to make it possible to gather more and better data from the safety of space.
BU geologist Magaly Koch is leading a project that will help fine-tune new techniques such as hyperspectral imaging, which uses the entire electromagnetic spectrum, from infrared to ultraviolet, to capture images of the ground. Because various features of the Earth’s surface, such as minerals and vegetation, reflect different parts of the spectrum, hyperspectral imaging enables researchers to see more details about the land from space.
“Arguably, it’s the most powerful remote sensing tool,” says Ronald Blom, a geologist who works with NASA’s Jet Propulsion Laboratory in Pasadena, CA. “Done properly, you can directly identify many materials, different soils, different rocks, different minerals, different types of vegetation.”
Koch and her colleagues are recording ground conditions in an arid part of central Spain and correlating them to hyperspectral readings of the area to create a key for translating that imagery into useful information.
With only 10 percent of the world’s deserts mapped by radar, El-Baz and his group still have plenty of frontiers to explore and are beefing up satellite imaging along the way. “Farouk understands where remote sensing needs to go for the future to meet the challenges that are before us,” says Blom.