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Detection and Measurement of Land-Surface Deformation, Pajaro Valley, Santa Cruz and Monterey Counties, California, 2015–18

Open-File Report 2021-1101
Water Availability and Use Science Program
Prepared in cooperation with the Pajaro Valley Water Management Agency
By: , , , and 
https://doi.org/10.3133/ofr20211101

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Abstract

Land-surface deformation (subsidence) caused by groundwater withdrawal is identified as an undesirable result in the Pajaro Valley Water Management Agency’s Basin Management Plan and California’s Sustainable Groundwater Management Act. In Pajaro Valley, groundwater provides nearly 90 percent of the total water supply. To aid the development of sustainable groundwater management criteria, the U.S. Geological Survey, in cooperation with the Pajaro Valley Water Management Agency, performed an analysis of land-surface deformation (subsidence and uplift) in Pajaro Valley for 2015–18, using Interferometric Synthetic Aperture Radar and continuous Global Positioning System methods. Land-surface deformation results were then compared with subsurface geology and groundwater altitudes to better understand the hydromechanical response of the coastal aquifer system. The results indicate the land surface is generally stable with only small magnitudes (less than 1 inch) of seasonal land-surface deformation (subsidence in the summer and uplift in the winter) during 2015–18. During this time, the largest magnitude of land-surface deformation was less than 2 inches of subsidence and was localized in one area just north of the city limits of Watsonville, California. Groundwater altitudes during 2015–18 demonstrated seasonal variability and annual to multi-annual increases after reaching historical lows by the mid-1990s. The small magnitudes of land-surface deformation coupled with groundwater-altitude increases in most areas indicate that the subsidence likely is largely elastic and recoverable. The Corralitos-Pajaro Valley groundwater basin contains fine-grained (clay) sediments that have the potential for permanent aquifer-system compaction and resultant land subsidence. However, groundwater altitudes throughout the Pajaro Valley have increased above historical lows, and observed increases in groundwater altitudes coincided with changes in groundwater management activities. Observed relations between groundwater management activities and groundwater altitudes indicate that management of groundwater supplies could minimize the potential for permanent land-surface deformation in Pajaro Valley.

Suggested Citation

Brandt, J.T., Earll, M.M., Sneed, M., and Henson, W., 2021, Detection and measurement of land-surface deformation, Pajaro Valley, Santa Cruz and Monterey counties, California, 2015–18: U.S. Geological Survey Open-File Report 2021–1101, 16 p., https://doi.org/10.3133/ofr20211101.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments  
  • Abstract  
  • Introduction  
  • Mechanics of Pumping-Induced Land Subsidence  
  • Interferometric Synthetic Aperture Radar (InSAR) 
  • Groundwater Altitudes  
  • Relation of Geology and Groundwater Altitudes to Land-Surface Deformation  
  • Summary and Conclusions  
  • References Cited 
Publication type Report
Publication Subtype USGS Numbered Series
Title Detection and measurement of land-surface deformation, Pajaro Valley, Santa Cruz and Monterey counties, California, 2015–18
Series title Open-File Report
Series number 2021-1101
DOI 10.3133/ofr20211101
Year Published 2021
Language English
Publisher U.S. Geological
Publisher location Reston, VA
Contributing office(s) California Water Science Center
Description Report: vi, 16 p.; Data Release
Country United States
State California
County Monterey County, Santa Cruz County
Other Geospatial Pajaro Valley
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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