Subsidence is a global problem and, in the United States, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence. More than 80 percent of the identified subsidence in the United States is a consequence of human impact on subsurface water.
There are concerns that fluctuating land-surface elevations due to subsidence and uplift in the valley could cause serious operational-maintenance and design construction problems for the California Aqueduct surface-water delivery system.
Surface-water imports via the California Aqueduct in the late 1960's and early 1970's, and the associated decrease in groundwater pumping, resulted in a steady recovery of water levels and a reduced rate of compaction. During the droughts of 1976-77, 1987-92, and 2007-09, diminished deliveries of imported water prompted increased groundwater pumping to meet irrigation demands. This increased pumping resulted in water-level declines reaching near historic lows and periods of renewed compaction. Following each of these droughts, recovery to pre-drought water levels was rapid and compaction virtually ceased.
Below are other science projects associated with this project.
Land Subsidence in the San Joaquin Valley
Below are multimedia items associated with this project.
- Overview
Subsidence is a global problem and, in the United States, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence. More than 80 percent of the identified subsidence in the United States is a consequence of human impact on subsurface water.
Sources/Usage: Public Domain.Map showing estimated regions of subsidence derived from interferograms for 2008–2010 and selected surface-water conveyance infrastructure in the San Joaquin Valley area of the Central Valley, California. (Public domain.) There are concerns that fluctuating land-surface elevations due to subsidence and uplift in the valley could cause serious operational-maintenance and design construction problems for the California Aqueduct surface-water delivery system.
Surface-water imports via the California Aqueduct in the late 1960's and early 1970's, and the associated decrease in groundwater pumping, resulted in a steady recovery of water levels and a reduced rate of compaction. During the droughts of 1976-77, 1987-92, and 2007-09, diminished deliveries of imported water prompted increased groundwater pumping to meet irrigation demands. This increased pumping resulted in water-level declines reaching near historic lows and periods of renewed compaction. Following each of these droughts, recovery to pre-drought water levels was rapid and compaction virtually ceased.
- Science
Below are other science projects associated with this project.
Land Subsidence in the San Joaquin Valley
The San Joaquin Valley is one of the most productive agricultural regions in the nation. Beginning around the 1920's, farmers relied upon groundwater for water supply. Over time, overpumping caused groundwater-level declines and associated aquifer-system compaction and land subsidence that resulted in permanent aquifer-system storage loss. - Multimedia
Below are multimedia items associated with this project.
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