This dataset represents measurements of vertical ground surface displacement in Bulletin 118 groundwater basins between spring of 2015 and summer of 2017. Image resolution is 0.0008333 degrees, or approximately 92 meters in north-south direction, and 70-77 meters in east-west direction (low end of range applies to northern latitudes and higher end of range applies to lower latitudes). Vertical ground surface displacement rates are derived from Interferometric Synthetic Aperture Radar (InSAR) data that are collected by the European Space Agency (ESA) Sentinel-1A satellite and processed by the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL), under contract with to the California Department of Water Resources (DWR). JPL presented preliminary processing results in the Progress Report: Subsidence in California, March 2015 – September 2016, and submitted a later version of the processing results that are still preliminary to the California Department of Water Resources (DWR). These files provided by JPL to DWR are multiband floating point GeoTIFFs with each band representing a date. GeoTIFF pixel values are in inches equal to the cumulative vertical displacement from the first date. JPL processed Sentinel-1A InSAR data separately for three different geographic regions; The Sacramento Valley, the San Joaquin Valley, and the South Central Coast. DWR temporarily interpolated the JPL data to end-of-month values, merged the resulting rasters from all three regions into a single raster for each month, and clipped all rasters to Bulletin 118 groundwater basins. DWR derived rasters for total vertical displacement relative to May 31, 2015, as well as rasters for annual vertical displacement rates, both in monthly time steps.
Data are considered public domain. DWR makes no warranties or guarantees — either expressed or implied — as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data.
This is an official DWR Image Service, published on 2/9/2018 by Ben Brezing of the DWR Division of Statewide Integrated Water Management, who may be contacted at [email protected] or (916) 651-9291.
Date of acquisition: Between Spring of 2015 and Spring of 2017.
Date of production: 2017.
Date of delivery of product: Delivered from NASA JPL to DWR in September of 2017.
Processing steps: See Progress Report: Subsidence in California, March 2015 – September 2016, Tom G. Farr, Cathleen E. Jones, Zhen Liu, Jet Propulsion Laboratory, 2016.
Pixel value definitions: Vertical ground surface displacement in inches for time period specified above.
Positional accuracy: See Progress Report: Subsidence in California, March 2015 – September 2016, Tom G. Farr, Cathleen E. Jones, Zhen Liu, Jet Propulsion Laboratory, 2016.
