Land subsidence caused by groundwater pumping has been a problem for decades in the San Joaquin Valley, but an increased reliance on aquifers during the last decade has resulted in subsidence rates in excess of a foot per year in some parts of the region.

In a report released in February 2017, NASA satellite-based and aircraft-based radar mapping prepared for the Department of Water Resources shows how this subsidence is putting state and federal aqueducts and flood control structures at risk of damage. Over time, long-term subsidence has destroyed thousands of public and private groundwater well casings in the San Joaquin Valley.

This special free briefing sponsored by the California Department of Water Resources and the Water Education Foundation highlighted the array of technologies available for subsidence measurement and monitoring, including information and technical support being provided by DWR. Going forward, groundwater sustainability agencies must address managing subsidence in their management plans pursuant to the Sustainable Groundwater Management Act. The briefing was held at the Alice Peters Auditorium (PB 191) in the University Business Center at Fresno State.

Topics discussed included:

• Update on valley groundwater conditions
• Update on SGMA program activities
• Techniques for monitoring land subsidence, including radar remote sensing, extensometers, and GPS data
• Gaps in subsidence monitoring today
• DWR technical assistance and resources for SGMA compliance