The agricultural economy continues to grow in this fourth year of severe drought, thanks mostly to the state’s vast but declining reserves of groundwater, which will offset about 70 percent of the surface water shortage this year, the researchers said.
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And now, a drought driven by climate change is causing parts of California, quite literally and quite quickly, to sink as it burns.
Compared to urban California, it says, “farmers are more vulnerable, but they are also adapting”.
The report was done in conjunction with NASA and found in some places the ground is sinking almost two inches each month, putting infrastructure on the surface at growing risk of damage.
Local agencies not in agreement with DWRs identification of critically overdrafted groundwater basins will have an opportunity next week to ask questions and make comments at a public meeting in Fresno.
However, local officials have until 2020 and in some cases until 2022 to write their management plans, so it could take another decade or two before California has a handle on groundwater use, Cowin said. In some areas, the land has sunk between 3 and 7 inches along the California Aqueduct and more than a foot east of Avenal.
According to California Department of Water Resources head Mark Cowin, groundwater pumping is now at “historic levels”, while groundwater levels are now at all-time lows, about 100 feet lower than the last data on file.
For Chase Hurley, general manager of the San Luis Canal Co., the recent state moves don’t amount to much.
The good news is that cities and suburbs have adapted well to the drought so far, and would likely continue to manage with less water for several years to come.
“The transition will cause some increased fallowing of cropland or longer crop rotations”, said Jay Lund, director of the UC-Davis Center for Watershed Sciences, in a statement, “but will help preserve California’s ability to support more profitable permanent and vegetable crops during drought”.
Subsidence has already led to closing of thousands of wells in San Joaquin Valley and over time, the phenomenon has been shown to permanently reduce underground aquifer capacity by squeezing out storage space for water. One area in the Sacramento Valley was descending about half-an-inch per month, faster than previous measurements, according to a report released Wednesday by the Department of Water Resources.
“We’re not ready to take a draconian approach to correcting this issue”, Cowin says. Within an aquifer, water is held in permeable sediments, and when it’s pumped out, the grains in the sediments compact.
“The most important thing that can happen is for counties to pass or strengthen ordinances that limit over-pumping”, he said.
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The department will also be making $10 million available to counties with stressed groundwater basins, to beef up water conservation.
