TRE ALTAMIRA InSAR Subsidence Data

Technical Report: InSAR land surveying and mapping services in support of the DWR SGMA program

The tutorial video on DWR’s SGMA Data Viewer and updated subsidence information is available at https://youtu.be/HxUNAprX078. DWR has updated the Sustainable Groundwater Management Program’s SGMA Data Viewer to include updated subsidence information to help Groundwater Sustainability Agencies (GSAs), water managers, and others implement the Sustainable Groundwater Management Act (SGMA). DWR is providing these standardized, statewide datasets to assist GSAs in the creation and ongoing development and implementation of Groundwater Sustainability Plans. The new information is available on the SGMA Data Viewer mapping application (https://sgma.water.ca.gov/sgmadataviewer#landsub) under the land subsidence heading and includes historical subsidence information from 1949 to 2005 and updated satellite based remote sensing InSAR data from June 2015 to June 2018. For additional subsidence related information please visit the DWR Groundwater Data and Tools webpage (https://water.ca.gov/Programs/Groundwater-Management/Data-and-Tools) and the California Natural Resources Open Data Platform (https://data.cnra.ca.gov/dataset?q=subsidence).

The SGMA Data Viewer provides access to groundwater related datasets that are organized by the requirements of SGMA and the Groundwater Sustainability Plan (GSP) regulations for the purpose of supporting GSP development and implementation.

The data range that a raster represents is indicated in the last 17 digits of the service name. Example 1, Total subsidence between June 13, 2015 and January 1, 2022: SAR/Vertical_Displacement_TRE_ALTAMIRA_Total_Since_20150613_20220101 Example 2; Annual Subsidence (rate) between January 1, 2021 and January 1, 2022: SAR/Vertical_Displacement_TRE_ALTAMIRA_Annual_Rate_20210101_20220101 **The image services carry the raw pixel values in addition to the RGB symbology values. To expose the raw pixel values in ESRI ArcMap or ArcGIS Pro, set the Processing Templates Function to ‘None’ in the raster layer properties. ** This TRE ALTAMIRA dataset represents measurements of vertical ground surface displacement in more than 200 of the high-use and populated groundwater basins across the State of California between January of 2015 and January of 2022. Image resolution (X,Y) is 0.0011335842, 0.00089982004 degrees, or approximately 100 meters. Vertical ground surface displacement estimates are derived from Interferometric Synthetic Aperture Radar (InSAR) data that are collected by the European Space Agency (ESA) Sentinel-1A satellite and processed by TRE ALTAMIRA, under contract with to the California Department of Water Resources (DWR) as part of DWR’s SGMA technical assistance to provide important SGMA-relevant data to GSAs for GSP development and implementation. Sentinel-1A InSAR data coverage for the entire study area began in June 13, 2015. Included in this dataset are rasters for total vertical displacement relative to June 13, 2015, as well as rasters for annual vertical displacement rates with earlier coverage for some areas, both in monthly time steps. The Department of Water Resources makes no warranties, representations or guarantees, either expressed or implied, as to the accuracy, completeness, correctness, or timeliness of the information in this dataset, nor accepts or assumes any liability arising from use of these data. Neither the Department nor any of the sources of this information shall be responsible for any errors or omissions, or for the use or results obtained from the use of this information. A Groundwater Sustainability Agency is not required to use these data, and their use does not guarantee the adequacy of a Groundwater Sustainability Plan that relies on such data. This is an official DWR Image Service, published on 6/17/2022 by Ben Brezing of the DWR Sustainable Groundwater Management Office, who may be contacted at Benjamin.brezing@water.ca.gov. Date of acquisition: Between January of 2015 and April of 2024. Date of production: 2024 Date of delivery of product: Delivered from TRE ALTAMIRA to DWR in March of May 2022. Processing steps: See Technical Report: InSAR Land Surveying and Mapping Services to DWR supporting SGMA - October 2021 update, TRE ALTAMIRA, 2021. Pixel value definitions: Vertical ground surface displacement in feet for time period specified above. Positional accuracy: See: InSAR Data Accuracy for California Groundwater Basins - CPGS Data Comparative Analysis - January 2015 to October 2020, Towill Inc., 2021