Water is scarce in arid Saudi Arabia. Now the king has hired a team of German scientists to search for groundwater trapped in aquifers beneath the massive kingdom's sands. Their pioneering work could provide solutions for other desert countries.

German geologist Randolf Rausch, 59, is showing his visitors the desert. He walks nimbly across the narrow crest of a sand dune, pointing his toes outward like a ballet dancer. The wind blows away his tracks immediately and tugs at his green Tyrolean hat.

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Rausch has been working for GTZ International Services, part of Germany's federal GTZ development agency, in Riyadh for the last six years. The Saudi king has hired him and his visitors, who are from the Technical University of Darmstadt, to search for water in the desert. By drilling holes up to 2,000 meters (6,560 feet) deep, conducting pumping tests, and applying complex measuring techniques and computer models, they are trying to find out how much fossil groundwater remains stored between layers of rock beneath the Arabian Peninsula.

The Helmholtz Center for Environmental Research (UFZ) in the eastern German city of Leipzig is also involved in the large-scale project. "Using the supercomputers at the UFZ," says Rausch, "we can simulate groundwater currents from the last ice age until today."