California has long suffered from
land subsidence.
Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. The principal causes are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, and thawing permafrost (National Research Council, 1991). Three distinct processes account for most of the water-related subsidence--compaction of aquifer systems, drainage and subsequent oxidation of organic soils, and dissolution and collapse of susceptible rocks.
The short way of saying that is California is sinking. Slowly, but surely, sinking.
A new study, using the newest in technologies has allowed scientists to get a better understanding of how much subsidence is going on and at what rate. The good news is that we have some pretty amazing technology. The bad news is that California is sinking faster than before and the
drought is the main culprit:
The state's sinking isn't new: California has long suffered from subsidence, and some parts are now a few dozen feet lower than they were in 1925, according to the U.S. Geological Survey.
But the state's worst drought on record — 97 percent of the state is facing moderate to exceptional drought — has only accelerated the trend. To quantify this accelerated sinking, researchers at the Department of Water Resources and NASA's Jet Propulsion Laboratory in Pasadena, California, compared satellite imagery of California over time. Thanks to images taken from both satellites and airplanes using a remote-sensing technique called interferometric synthetic aperture radar (InSAR), which uses radar to measure elevation differences, researchers can now map changes in the surface height of the ground with incredible precision. For the current study, the team stitched together imagery from Japan's satellite-based Phased Array type L-band Synthetic Aperture Radar and Canada's Earth Observation satellite Radarsat-2, as well as NASA's airplane-based Uninhabited Aerial Vehicle Synthetic Aperture Radar.
There are places that have sunk 13 inches in eight months! Most of the stresses on our water supply is agricultural.
The unquenchable thirst for groundwater in certain regions is largely a result of agriculture: Most of the state's agricultural production resides in the fast-sinking regions around some of the state's most endangered river systems — the San Joaquin and Sacramento rivers. As the heat and lack of rainfall have depleted surface-water supplies, farmers have turned to groundwater to keep their crops afloat.
None of this is surprising in as much as we know the drought in California is bad news with serious lifestyle consequences. However, what this study presents is another reason it is crucial we invest in our infrastructure—the other big reason of course,
earthquakes.