NASA - Groundwater Pumping From CA Central Valley Lowering Ground By Up To Two Inches Per Month
FRESNO, Calif. (AP) — Vast areas of California's Central Valley are sinking faster than in the past as massive amounts of groundwater are pumped during the historic drought, state officials said Wednesday, citing new research by NASA scientists. The data shows the ground is sinking nearly two inches each month in some places, putting roads, bridges and vital canals that deliver water throughout the state at growing risk of damage.
Sinking land has occurred for decades in California because of excessive groundwater pumping during dry years, but the new data shows it is happening faster as the state endures its fourth year of drought. "We are pumping at historic levels," said Mark Cowin, head of the California Department of Water Resources. He added that groundwater levels are dropping to record levels — up to 100 feet lower than previously recorded.
Scientists at NASA's Jet Propulsion Laboratory did the research using images taken over time from satellites and airplanes. California is the nation's leading agriculture state, but drought has put one-fifth more land out of production this year than last year.
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The NASA data shows land near the city of Corcoran sank 13 inches in eight months, and part of the California Aqueduct dropped eight inches in four months last year. The aqueduct spans hundreds of miles and provides water to million people and about vast areas of farmland. Farmers in the Central California Irrigation District have spent $4.5 million to raise the walls on a canal and intend to pay $2.5 million to raise a bridge above the water.
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http://www.usnews.com/news/us/articles/2015/08/19/report-groundwater-pumping-in-california-has-land-sinking
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This photograph shows 30 feet of subsidence in 52 years between 1925 and 1977.
What's even worse is the fact that the subsidence has altered drainage patterns in the area to the point where it became impossible to drain away fertilizer salts that accumulated in the soil from years of irrigation, basically poisoning the ground and making it impossible to grow anything there.
[font size=5]NASA: California Drought Causing Valley Land to Sink[/font]
[font size=3]As Californians continue pumping groundwater in response to the historic drought, the California Department of Water Resources today released a new NASA report showing land in the San Joaquin Valley is sinking faster than ever before, nearly 2 inches (5 centimeters) per month in some locations.
The report, Progress Report: Subsidence in the Central Valley, California, prepared for DWR by researchers at NASA's Jet Propulsion Laboratory, Pasadena, California, is available at:
http://water.ca.gov/groundwater/docs/NASA_REPORT.pdf
“Because of increased pumping, groundwater levels are reaching record lows -- up to 100 feet (30 meters) lower than previous records,” said Department of Water Resources Director Mark Cowin. “As extensive groundwater pumping continues, the land is sinking more rapidly and this puts nearby infrastructure at greater risk of costly damage.”
Sinking land, known as subsidence, has occurred for decades in California because of excessive groundwater pumping during drought conditions, but the new NASA data show the sinking is happening faster, putting infrastructure on the surface at growing risk of damage.
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Total subsidence in California's San Joaquin Valley for the period May 3, 2014 to Jan. 22, 2015, as measured by Canada's Radarsat-2 satellite. Two large subsidence bowls are evident, centered on Corcoran and south of El Nido.
Credits: Canadian Space Agency/NASA/JPL-Caltech
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