In a recent study, scientists found that a previously unmeasured source – 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.
In a recent study, scientists found that a previously unmeasured source – 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. This underground source accounts for about 10% of all the water that enters this highly productive farmland each year from every source (including river inflows and precipitation).
The Central Valley encompasses only 1% of U.S. farmland but produces 40% of the nation’s table fruits, vegetables, and nuts annually. That’s only possible because of intensive groundwater pumping for irrigation and river and stream flow captured in reservoirs. For at least 60 years, growers have been pumping more water from aquifers than can be replenished by natural sources, causing the ground level to sink and requiring wells to be drilled deeper and deeper.
As water grows more scarce in the Central Valley due to climate change and human use, a more detailed understanding of the natural movement of groundwater offers a chance to better protect the remaining resources.
In the recently published study led by scientist Donald Argus of NASA’s Jet Propulsion Laboratory in Southern California, researchers found that groundwater volume fluctuates more widely between dry and wet years than had been previously understood. In particular, the scientists observed a greater loss of groundwater during dry years than earlier studies had estimated. Argus and colleagues estimated that the Central Valley lost about 1.8 million acre feet (2.2 cubic kilometers) of groundwater per year between 2006 to 2021.
Read more at NASA
Photo Credit: Designtek via Pixabay
