Gravity measurements are attracting attention for monitoring groundwater storage changes due to their sensitivity to subsurface mass variations. Changes in groundwater storage through recharge or extraction lead to mass redistribution within the subsurface, which induces subtle variations in surface gravity. These variations can be detected using gravimeters. Recently, high-precision superconducting gravimeters (SGs) have been emerged as a new approach to groundwater monitoring. The SGs can detect gravity variations as small as 0.1 μGal, allowing to track subtle gravity changes induced by groundwater fluctuations. The SGs are well-suited for detecting long-term and gradual mass changes associated with groundwater, and can provide insights into aquifer heterogeneity. These characteristics highlight their substantial potential in hydrogeological investigations. This paper presented the fundamental principles and key advantages of SGs, and explored their applicability to groundwater monitoring through a review of selected case studies. Additionally, it reviewed essential aspects of data processing and correction, and proposed future directions for the broader application of SGs. Although the successful application of SGs to groundwater studies requires the isolation of groundwater signals through precise data corrections with various auxiliary observations (e.g., groundwater levels), interdisciplinary collaboration can facilitate this process. This, in turn, enables the early detection of groundwater changes and supports sustainable groundwater resources management.

Keywords: Groundwater storage, Monitoring, Superconducting gravimeter, Data corrections, Groundwater signals