LOS ANGELES, Jan. 24 (Xinhua) -- Water flowing deep underground from the Sierra Nevada into California's Central Valley provides 10 percent of all water entering the valley, according to a new NASA study.
The Central Valley encompasses only 1 percent of U.S. farmland but produces 40 percent of the nation's table fruits, vegetables, and nuts annually.
That is only possible because of intensive groundwater pumping for irrigation and river and stream flow captured in reservoirs, according to NASA.
In the new study led by scientist Donald Argus of NASA's Jet Propulsion Laboratory in Southern California, scientists found that water percolating through soil and fractured rock below California's Sierra Nevada mountains delivers an average of 4 million acre feet (5 cubic kilometers) of water to the state's Central Valley each year.
Researchers also found that groundwater volume fluctuates more widely between dry and wet years, and observed a greater loss of groundwater during dry years. They estimated that the Central Valley lost about 1.8 million acre feet (2.2 cubic kilometers) of groundwater per year between 2006 to 2021.
This new data could be used to better match usage with the available groundwater resources, according to NASA. ■
