An Update on Land Subsidence & Aquifer Storage Change Monitoring in the Tucson AMA

Pima County Regional Flood Control District Monthly Brown Bag Series
By Rob Carruth – USGS Water Science Center

12:00 Wednesday, April 13 | 201 N. Stone – 9th Floor, Room C

Land-surface elevation change is monitored at a network of benchmarks throughout the Tucson AMA by measuring changes in land surface elevation over time (approximately annually) with targeted GPS surveys and more broadly throughout the AMA with Interferometric Synthetic Aperture Radar (InSAR). The InSAR data are used by ADWR to produce a land-surface elevation-change map over the same time period as the targeted GPS surveys conducted by the USGS.

Aquifer storage change is monitored by measuring changes in gravity over time at the same network of benchmarks. Gravity is affected by mass and distance; a change in mass or a change in elevation will cause a change in gravity. Groundwater depletion is a mass change and land-surface elevation change is a distance change. By removing the effect of change in distance, changes in gravity are used to determine changes in aquifer storage.

 

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