The GRACE satellites have tracked water movement from the Central Valley since 2003
SAN FRANCISCO — In the past six years, the irrigation of crops in California’s Central Valley has pulled groundwater from aquifers there at rates that are unsustainable if current trends continue, scientists say.
The Central Valley, which covers about 52,000 square kilometers, is one of the world’s most productive agricultural regions, says Jay Famiglietti, director of the University of California Center for Hydrologic Modeling in Irvine. In 2002, farmers there produced more than 250 different crops worth a total of around $17 billion — an amount that adds up to around one-twelfth of the nation’s agricultural production, he notes.
But the productivity of those fertile fields is increasingly at risk: Satellite data suggest that more than 20 cubic kilometers of groundwater has been pumped from the valley’s aquifers since October 2003, Famiglietti reported December 14 at the fall meeting of the American Geophysical Union. That&rsquo