Quinn Welsch<\/p>\n
(CN) \u2014\u00a0A new\u00a0study<\/a>\u00a0of groundwater in California\u2019s Sacramento Valley shows that the ground sank faster than expected during the\u00a02020-2022 drought<\/a>\u00a0due to heavy groundwater pumping, resulting in less water storage capacity in the aquifer.<\/p>\n The authors of the study published Monday in the Proceedings of the National Academy of Sciences say the damage to the aquifer may be long-term and irreversible.<\/p>\n Land subsidence occurs when excessive groundwater is withdrawn from rocks and sediment, causing the ground to sink, according to the\u00a0U.S. Geological Survey<\/a>. As groundwater is depleted, aquifers become more susceptible to compaction because the water no longer provides enough underground pressure to support the overlying land.<\/p>\n \u201cAs global demand for groundwater intensifies in response to climate change, its ability to act as a buffer against surface water variability becomes increasingly critical,\u201d the\u00a0authors write<\/a>. \u201cA growing concern, however, is that intensive exploitation of groundwater resources can damage aquifer systems and hence threaten future groundwater availability.”<\/p>\n The researchers used high-resolution satellite measurements to track ground deformation and groundwater levels in the Sacramento Valley from 2016 to 2022.<\/p>\n Their analysis found the land initially exhibited elastic deformation, allowing it to rebound. But during the 2020-2022 drought, subsidence accelerated beyond the normal rate of elastic deformation by up to\u00a0several decimeters, or about roughly a foot, per year.<\/p>\n The\u00a0Northern California Water Association<\/a>\u00a0considers the 2020-2022 drought the worst in the region\u2019s recorded history. The drought strained farmland, the environment and drinking water supplies, leading to increased groundwater pumping that the authors say likely drove the accelerated subsidence.<\/p>\n Stacy Larochelle, a professor of geophysics at the University of California Los Angeles, said that this subsidence could have other long term implications for the region.<\/p>\n \u201cWhen we lose permanent storage capacity and also the ability for the aquifer system to recharge, that means we\u2019re going to have less groundwater in the future,\u201d Larochelle, an author of the study, told Courthouse News. \u201cThat\u2019s a major problem under climate change because we\u2019re going to be relying on groundwater more.\u201d<\/p>\n Additionally, land subsidence could increase flood risk and damage irrigation canals, roads and other infrastructure.<\/p>\n The Sacramento Valley is one of California\u2019s largest\u00a0agricultural regions<\/a>, producing about 21% of the state\u2019s irrigated field crops. Stretching 150 miles across the northern Central Valley, it spans multiple counties from Redding to Sacramento.<\/p>\n Scientists have documented land subsidence in the San Joaquin Valley, farther south in the Central Valley,\u00a0since the 1970s<\/a>. The state\u2019s\u00a0Sustainable Groundwater Management Act<\/a>\u00a0designates its groundwater basin as\u00a0critically overdrafted<\/a>.<\/p>\n Larochelle said the new study shows the Sacramento Valley should receive the same designation.<\/p>\n Larochelle and her coauthors also say the abrupt increase in land subsidence during the drought could not have been predicted from groundwater records alone.<\/p>\n