The New York Times reports that, "Across Yemen, the underground water sources that sustain 24 million people are running out, and some areas could be depleted in just a few years. It is a crisis that threatens the very survival of this arid, overpopulated country, and one that could prove deadlier than the better known resurgence of Al Qaeda here."
"The government now supplies water once every 45 days in some urban areas, and in much of the country there is no public water supply at all. Meanwhile, the market price of water has quadrupled in the past four years, pushing more and more people to drill illegally into rapidly receding aquifers."
"For millenniums, Yemen preserved traditions of careful water use. Farmers depended mostly on rainwater collection and shallow wells. In some areas they built dams, including the great Marib dam in northern Yemen, which lasted for more than 1,000 years until it collapsed in the sixth century A.D."