In areas adjacent to the Delta-Mendota Canal (DMC), extensive groundwater withdrawal has caused areas of the ground to sink as much as 10 feet, a process known as land subsidence. In an effort to understand and manage land subsidence in the area, the USGS has put in place a land subsidence monitoring network.
Land Subsidence Monitoring Network
The Land Subsidence Monitoring Network is made up of a suite of tools and techniques that capture integrated measurements of land subsidence in the DMC and the Central Valley, including: Interferometric Synthetic Aperture Radar (InSAR); Continuous Global Positioning System (CGPS) Stations; Extensometers; and Piezometers.Explore the data map!
Interferometric Synthetic Aperture Radar (InSAR)
For the DMC study, scientists use persistent scatterer InSAR to better understand land surface movement. This technique requires 20 or more satellite images taken at different times. The images are then processed to reveal relative ground-elevation change over the time the images were taken. The processed images are displayed as maps, called interferograms, that scientists interpret to see land elevation change along the DMC. The InSAR data is then combined with available historical spirit leveling, extensometer, and GPS data to produce information that describes land subsidence and aquifer-system compaction over a period of time.
The interpreted persistent scatterer InSAR data will be used to create maps of changes in land-surface elevations along the DMC. The InSAR data will be combined with available historical leveling, extensometer, and GPS data to produce a time series of land subsidence and aquifer-system compaction.