Minor changes in precipitation may have major impact on groundwater supplies in arid regions

December 6, 2010

By Cathryn Delude
Correspondent, Civil & Environmental Engineering

People living in the great expanses of flat, dry regions of the world that lack natural freshwater lakes depend on episodic rainstorms to replenish the groundwater they use for domestic and agricultural purposes. New work by researchers in CEE shows that even minor variations in precipitation caused by climate change could cause major, often counterintuitive changes to fragile groundwater supplies in these areas.

For example, if the future brings drier winters but wetter summers to the Texas High Plains, annual rainfall could increase 10 percent but recharge — the water that soaks deep into the ground to replenish groundwater — would drop 10 percent, largely because the area’s rain-fed cotton crops would soak up the summer rain. Likewise, 20 percent less precipitation, falling mainly in summer, could reduce groundwater recharge by 75 percent, but because of the rain’s timing, c