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| 'Providing a source of clean water would remove one of the main causes of conflict.' – Farouk El-Baz, Center for Remote Sensing Tom Peter |
How a desert detective found water in Darfur – from half a world away
Farouk el-Baz heads to Sudan next month to site wells over what he believes is a vast reserve from an ancient lake.
from the October 17, 2007 edition
Page 2 of 3
As the conflict in Darfur escalated, Baz and his team at BU turned their attention to the paleohydrology (ancient water) of the region, to see if a similar water source was available.
A year and a half ago, one of his research assistants, Eman Ghoreim, was poring over satellite radar images of Sudan when she noticed some narrow, dark lines set close together. Fractures in the bedrock? Something else? Baz took a look.
From his field research in the Sahara and his past discoveries, Baz knew the lines might indicate gravel deposits. Sand is easily penetrated by satellite radar; the bedrock beneath it shows up as off-white in the images. But gravel and similar sediments cannot be penetrated by radar, and they appear darker on the image. Baz suspected that it was gravel deposited by an ancient water source during the last wet age in the region, some 5,000 to 11,000 years ago. The lines might indicate the banks of an ancient lake, with multiple lines indicating the shore shrinking as the climate dried out.
To confirm their finding, Ms. Ghoreim and Baz examined other types of radar and topographical imagery. An image using radar data from the space shuttle showed darker grooves beneath the sand that led up to what they thought was shoreline. Were they ancient dry rivers that had fed the lake?
"Some people said, 'Oh, those lines are just fractures,' " Ghoreim says. "But when we found that they all stopped exactly along the 'shoreline,' we knew that probably wasn't true."
Topographic images then showed the elevations in the surrounding area. The land in and around the suspected ancient lake was flat and low, typical of a lakebed, and it rose like the lip of a plate near the dark lines that indicated a shoreline.
Looking more closely, the BU team found other bits and pieces of shoreline.
They put the data into a powerful computer loaded with special geology software. The program ran for three days, processing satellite images and researchers' findings, before it spat out an image of what the lake might have looked like, given the location and size of the tributaries, the shoreline fragments, and other geographic considerations. The resulting image showed a deep lake about the size of Massachusetts.
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