Food Security In The U.S. Threatened By Groundwater Depletion

United States food security might be threatened by an alarming depletion of groundwater across the Central Valley of California and the High Plains of the central U.S. due to irrigation.

The study elicited three main points:

- During the 2006-2009 drought, farmers from California's Central Valley used up enough water to fill the nation's largest man-   made reservoir, Lake Mead. This rate of depletion is unsustainable at the current rate of recharge.

- A third of the groundwater depletion in the High Plains area occurs in only four percent of the land area.

- Lastly, that some areas like the Texas Panhandle and western Kansas will no longer be able to support irrigated agriculture if the current trend continues

"We're already seeing changes in both areas," said Bridget Scanlon, senior research scientist at The University of Texas at Austin's Bureau of Economic Geology and lead author of the study. "We're seeing decreases in rural populations in the High Plains. Increasing urbanization is replacing farms in the Central Valley. And during droughts some farmers are forced to fallow their land. These trends will only accelerate as water scarcity issues become more severe."

The Central Valley of California and the High Plains of the central U.S. produce up to $56 billion worth of agricultural products, making the two regions the major producers of the U.S. food crop. The Central Valley is known as the "fruit and vegetable" basket of the U.S., while the High Plains are the "grain basket." As a result of irrigating crops, the two regions also account for half the groundwater depletion in the U.S.

Scanlon also suggested improvements that might lessen groundwater depletion in California's Central Valley. Instead of using flood irrigation systems, she said, farmers should turn to a more efficient sprinkle-and-drip system. And excess groundwater should be stored for future use in the very reservoirs that supply irrigation water.

The future for irrigated crops in the High Plains, however, doesn't look so promising.

"Basically irrigated agriculture in much of the southern High Plains is unsustainable," said Scanlon.