NASA study offers new tool for groundwater management

Researchers from NASA's Jet Propulsion Laboratory (JPL) in Southern California and the U.S. Department of Energy's Lawrence Berkeley Laboratory in Northern California claim to have found a new method that may improve groundwater management.

The team studied California's Tulare Basin, an indispensable source of groundwater within the Central Valley. The underground water resource is subsiding drastically - the current rate is about one foot (0.3 meters) of sinkage per year.

The new method sorts out how much underground water loss comes from aquifers confined in clay and how much comes from soil that's not confined in an aquifer.

The research team combined data on water loss from NASA's Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellites with data on ground-level changes from a ESA (European Space Agency) Sentinel-1 satellite to monitor the hydrological variations within the Tulare Basin.

Ground-level changes in this region are often related to water loss because when the ground is drained of water, it eventually slumps together and sinks into the spaces where water used to be – a process called subsidence.

The team developed a simple numerical model of these two layers of soils in the Tulare Basin. By removing the long-term subsidence trend from the ground-level-change data, they produced a dataset of only the month-to-month variations. The new model revealed that on this time scale, virtually all of the ground-level change can be explained by changes in aquifers, not in the water table.

According to Kyra Kim, a postdoctoral fellow at JPL and co-author of the paper published in Scientific Reports, the new model can be repurposed to represent other agricultural regions where groundwater use needs to be better monitored.

Untangling puzzling patterns 💧Scientists found a new process that may improve groundwater management – a critical component to both life & agriculture in dry regions. The method pins down underground locations where water is being pumped for irrigation. https://t.co/MlyhRV18o6 pic.twitter.com/BcX1Z1cwWp

— NASA JPL (@NASAJPL) April 5, 2022

NASA and ISRO's (Indian Space Research Organisation) upcoming mission - Synthetic Aperture Radar (NISAR) - will measure changes in ground level at an even higher resolution than Sentinel-1. This mission is planned to launch in 2023.