Over the last thirty years, Saudi Arabia has drilled its soil in search of a resource far more precious than oil: water. The Wadi as-Sirhan Basin's engineers and farmers have used little-known reservoirs to farm grains, fruits, and vegetables in the Saudi desert.
This artificially colored series of images taken in 1987, 1991, 2000, and 2012 shows farming's evolution in the basin. Recently planted surfaces are in green, dry vegetation and fallow land are rust-colored, and dry and bare surfaces (principally desert) are pink and yellow.
No one knows how much water lies under the desert; estimates vary from 60 to 208 cubic miles. Hydrologists have stated that, from an economic perspective, it will only be realistic to pump this resource for a period of fifty years.