Water has been near the top of the headlines lately, and will continue to generate debate as the drought in California and much of the West reaches unprecedented proportions. And as water sources turn dry and municipalities claim a larger share of the resource, agriculture will need to adjust.
The recent National Institute for Animal Agriculture (NIAA) conference focused on the theme of “Water and the Future of Animal Agriculture. The program kicked off with a presentation from hydrologist Jay Famiglietti, PhD, a professor of earth-systems science and civil and environmental engineering at the University of California, Irvine, and the senior water scientist at the NASA Jet Propulsion Laboratory at the California Institute of Technology.
Famiglietti and NASA scientists have spent 30 years developing satellites, monitoring systems and computer models for tracking and predicting water trends. In 2002, NASA launched a pair of satellites known as the Gravity Recovery and Climate Experiment, or GRACE. The two GRACE satellites, orbiting 310 miles above the earth, act as a kind of scale, measuring changes in the volume of water in a region by measuring subtle changes in gravitational pull.
Through these studies and others, Famiglietti estimates total water storage in California has declined by 8 trillion gallons per year over the past three years. According to an article on the GRACE website, High Plains aquifers have lost a volume of water nearly equal to that in Lake Tahoe over the past decade.
Overall U.S. water supplies have declined since 2002 in much of the West, Southern Plains and Southeast. In California, with the ongoing drought persisting and surface water mostly depleted, the state is shifting toward nearly 100 percent reliance on groundwater, Famiglietti says, which in some cases is not renewable or takes many years to recover. Globally, groundwater accounts for about one-third of all water withdrawals.
Scientists have developed models for sorting out data from the GRACE satellites to subtract out surface water, allowing them to monitor changes in groundwater supplies, Famiglietti says. In California, they have noted a trend in which groundwater recovers somewhat in years when surface water is available and declines when surface water is depleted. Over the long-term though, the declines are greater than the recovery in wet years.
Changes in climate patterns, and water cycles generally have resulted in wet regions around the world getting wetter and dry regions getting dryer, Famiglietti says. He believes that for agriculture to remain productive, we need to change the dialog on water, and shift away from the “us versus them” conflict between agriculture and other users that tends to emerge when water supplies become scarce. We need better-defined processes for deciding how to allocate water for various uses and need to learn to produce food with less water.
In some cases, he says, we might need to shift some types of agricultural production away from areas experiencing long-term water shortages into areas with more sustainable supplies.
A video of Famiglietti’s presentation is available on the NIAA website.