A newly found imprint of a vast, ancient underground lake in Sudan's Darfur could restore peace to the region by providing a potential water source to an area ravaged by drought, a U.S. geologist says.

"What most people don't really know is that the war, the instability, in Darfur is all based on the lack of water," said Farouk el-Baz, director of Boston University's Center for Remote Sensing.

The potential water deposits were found with radar that allowed researchers to see inside the depths of the desert sands. The images, el-Baz said, uncovered a "megalake" of 19,110 square miles (30,750 sq km) -- three times the size of Lebanon.

International experts estimate 200,000 people have died in four years of rape, killing and disease in Darfur, violence the United States calls genocide. Sudan rejects that term and puts the death toll at 9,000.

Widespread environmental problems are a root cause of Sudan's violence, the U.N. Development Programme said in a report last month, noting that deserts had spread southwards by an average of 62 miles (100 km) over the past four decades.

Many refugees from Darfur settled in regions that were once the domain of nomads, straining water resources and sowing conflict between farmers and nomads, said el-Baz.

"So now, if you find water for the farmers ... in addition to that for the nomads ... for agricultural production, to feed them, to give them grain, then you resolve the problem completely," he told Reuters in an interview.

His initiative, called 1,000 Wells for Darfur, has gained the support of the Egyptian government, which has pledged to start building an initial 20 wells.

El-Baz, who expects groundwater deposits below the surface can be drilled for water, hopes for backing from other regional governments and has urged non-governmental organizations to get involved.

GROUND WATER

"As we began to look into this, we realized we were dealing with a vast low area, a depression. And then we began to look at the details of the depression and we actually found the terraces, meaning the edges of the lake, way up on the nearby mountains," he said.

"That's why we call it a megalake, because it is an incredibly large lake. It is the size of the state of Massachusetts, or Lake Erie."

Researchers said the ancient lake would have contained about 607 cubic miles (2,530 cubic km) of water when full during past humid climate phases.

"One thing is certain, much of the lake's water would have seeped through the sandstone substrate to accumulate as groundwater," el-Baz said in a report.

El-Baz, who worked on NASA's Apollo program as a supervisor of lunar science planning, conducted similar research in Egypt that led to the construction of 500 wells in an arid region of his native country.

That project helped irrigate up to 150,000 acres (60,700 hectares) of farmland where wheat and other crops are grown.

"As proven earlier in southwest Egypt, just northeast of Darfur, a similar former lake is underlain by vast amounts of groundwater," he said.