GLOBAL ASSESSMENT OF MANAGED AQUIFER RECHARGE SUCCESS FOR MITIGATING LAND SUBSIDENCE

Groundwater depletion, driven by rising demand and changing climatic patterns, poses severe challenges worldwide, including land subsidence, threatening ecosystems, agriculture, and infrastructure. Excessive groundwater extraction may exacerbate these issues, making sustainable water management critical. Managed aquifer recharge (MAR) is a technique to replenish groundwater and potentially mitigate land subsidence. However, the global environmental impacts and effectiveness of MAR as a strategy for subsidence hazard mitigation remain underexplored. In this study, we assessed the effectiveness of MAR at 12 sites across 10 countries. We employed Interferometric Synthetic Aperture Radar (InSAR) measurements between 2015 to 2023 to analyze the vertical land motion (VLM) at these sites and compared the land motion to changes in groundwater storage using groundwater level data. Our results show uplift with average rates between 0.1 to 5 mm/yr at 6 MAR sites (Orange County, USA; Phoenix, Arizona; Geneva, Switzerland; Lucca, Italy; Turku, Finland; Perth, Australia ), while the other sites (Central Platte, USA; Sidfa, Egypt; Koksijde, Belgium; El Carracillo, Spain; Cape Town, South Africa; Haridwar, India) exhibited subsidence of more than 1 mm/yr. A comparison of the average VLM with the MAR recharge volume across all sites shows a correlation value of 0.4, suggesting active recharge drives the changes in the land elevation at MAR sites. To understand the broader context of these observations, we compiled precipitation and Gravity Recovery and Climate Experiment (GRACE) datasets to understand the influence of climatic variation on groundwater volume changes. These results indicate that at sites where the land is subsiding, low precipitation levels contribute to the decline in total water storage and, thus, decreased groundwater levels, and vice versa. The findings suggest that MAR can mitigate subsidence in areas experiencing groundwater depletion, providing insights into optimal water storage practices and guiding future sustainable water management strategies amidst current climate change challenges.