Feb 15, 2025 01:20 AM
https://sustainability.stanford.edu/news...tudy-finds
EXCERPTS: The researchers analyzed the impact of 2023’s historic series of atmospheric river storms, which dumped more than 140% of California’s 20th-century average annual precipitation in just three months. Those rains, combined with torrential rainfall from an August storm that began as Hurricane Hilary, nearly refilled surface reservoirs and shallow aquifers depleted by decades of drought and groundwater extraction, the Feb. 14 study in Science shows.
But even a year of extreme precipitation failed to replenish aquifers located 50 meters or more below the surface. Unlike the shallow aquifers, these deeper aquifers regained only about 25% of the groundwater they had lost since 2006. [...] “It appears that a single epic storm season is not enough to restore the groundwater depletion accumulated over the recent droughts. It will take many more wet years for the deep aquifers to fully recover...”
[...] Given the efficiency and the resolution of the new method, the authors hope that water managers use their new approach to assess ways to ensure more precipitation can be diverted to seep back into the underground reservoirs, which are estimated to be able to store as much as 17 times the volume of water as California’s major surface reservoirs.
Another open question is whether, after prolonged droughts and historic overuse, the porous aquifers have not collapsed to the point where they are unable to hold as much water as they once did. Ellsworth noted that land in the southern San Joaquin Valley has sunk tens of feet over a period of decades due to aquifer depletion.
“The loss of aquifer storage capacity can be irreversible,” Mao said. “We hope that our method can help water agencies to fill gaps in their monitoring data, refine hydrologic modeling, and inform decisions about water use and conservation.” (MORE - missing details)
EXCERPTS: The researchers analyzed the impact of 2023’s historic series of atmospheric river storms, which dumped more than 140% of California’s 20th-century average annual precipitation in just three months. Those rains, combined with torrential rainfall from an August storm that began as Hurricane Hilary, nearly refilled surface reservoirs and shallow aquifers depleted by decades of drought and groundwater extraction, the Feb. 14 study in Science shows.
But even a year of extreme precipitation failed to replenish aquifers located 50 meters or more below the surface. Unlike the shallow aquifers, these deeper aquifers regained only about 25% of the groundwater they had lost since 2006. [...] “It appears that a single epic storm season is not enough to restore the groundwater depletion accumulated over the recent droughts. It will take many more wet years for the deep aquifers to fully recover...”
[...] Given the efficiency and the resolution of the new method, the authors hope that water managers use their new approach to assess ways to ensure more precipitation can be diverted to seep back into the underground reservoirs, which are estimated to be able to store as much as 17 times the volume of water as California’s major surface reservoirs.
Another open question is whether, after prolonged droughts and historic overuse, the porous aquifers have not collapsed to the point where they are unable to hold as much water as they once did. Ellsworth noted that land in the southern San Joaquin Valley has sunk tens of feet over a period of decades due to aquifer depletion.
“The loss of aquifer storage capacity can be irreversible,” Mao said. “We hope that our method can help water agencies to fill gaps in their monitoring data, refine hydrologic modeling, and inform decisions about water use and conservation.” (MORE - missing details)