Under SGMA, land subsidence is considered a sustainability indicator. SGMA requires that GSAs investigate the connection and interaction between groundwater and land subsidence, and to demonstrate an absence of 'Significant and unreasonable land subsidence that substantially interferes with surface land uses'. Measurable objectives and minimum thresholds need to be established for land subsidence.
Chapter 2 - the Basin Setting of the Yolo Groundwater Sustainability Plan describes studies of land subsidence in the Yolo Subbasin. Some of the studies that are referenced in this section of the GSP are displayed below.
DWR InSAR Vertical Displacement
The California Department of Water Resources is utilizing satellite technology to detect changes in land surface elevation and report on land subsidence throughout the state. Data is updated quarterly.
2017 GPS Survey of the Sacramento Valley Subsidence Network
The California Department of Water Resources conducted a re-observation of subsidence in the Sacramento Valley Network in summer 2017. The Final Report was released in December 2018.
2016 Yolo Subsidence Network Observation Event
The WRA Board approved the Technical Committee's recommendation to allocate a portion of the FY15-16 project fund budget for an re-observation event of the Yolo County Subsidence Network in 2016. The observation data was collected in June 2016 with the leadership of Jim Frame, Frame Surveying & Mapping, from Davis. The WRA, Yolo County, Conaway Ranch and the Yolo County Flood Control & Water Conseration District provided the funding for this project. The project's proposed budget was $93,000, but ended up coming in under budget at $74,000.
2008 Update on Sacramento Valley GPS Height-Monitoring Project
The Yolo County Subsidence Network monitoring project was the template and inspiration for DWR to expand a monitoring project throughout the Sacramento Valley. Jim Frame, Frame Surveying and DWR staff are coordinating the surveying activities. In Yolo County, the cities of Davis and Woodland, Yolo County Flood Control & WCD, and UC Davis have committed staff or equipment to the project in addition to paticipation by local agencies in at least six counties in Northern California. Observations in Yolo County took place between May 2 to May 22, 2008. Click the link below for the final 2008 report.