Increasing consumption of water for agriculture and food production, as consequence of feeding an ever growing world population, is causing geographical expansion of “Peak Water” around the world. Lack of sufficient water for irrigation and food production is already turning vast regions of land to “virtual deserts” that gradually and eventually will develop to permanent deserts through an accelerating degradation of soil quality and erosion of top fertile soils.

Also, the increasing decoupling of “surface water – groundwater” through the action of “Peak Water” in combination with degradation in soil quality, i.e. decreasing organic content “mineralisation”, will force increasing water-consumption for irrigation with gradual development of “Virtual deserts”. Furthermore, excessive use of surface water and groundwater pumping in combination with global warming will enhance expansion of dry land.

http://www.theguardian.com/global-development/2013/jul/06/food-supply-threat-water-wells-dry-up