Microgravity monitoring of groundwater dynamics in a shallow aquifer in Al-Ain (Abu Dhabi Emirate, United Arab Emirates): an opportunity for understanding aquifer hydrodynamics in arid regions

Microgravity monitoring was performed at four water wells in Al-Ain City (Abu Dhabi Emirate, United Arab Emirates) to understand the hydrodynamic characteristics of the shallow groundwater aquifer. Measurements of microgravity and water level at Wells 1–4 started in March 2018 and ended in March 2019, omitting the month of June due to weather conditions. A combination of time-lapse measurements of microgravity and groundwater levels in the wells was used to estimate the changes in groundwater storage from April 2018 to March 2019. Spatiotemporal changes in microgravity at the four water wells showed amplitudes between − 343.5 and 978.1 µGal with respect to a local reference. Water levels changes ranged between 1.85 and 3.95 m in March 2019 relative to March 2018. The calculated average water storage changes based on microgravity (∆S_g) ranged from 0.28 to 1.58 m over the entire study period for a specific yield (S_y) ranging from 15 to 40%. The average volume storage changes (∆S_h) for the study period ranged from 0.3 to 1.6 million m³ (with 15% < S_y < 40%). The microgravity method is recommended for monitoring shallow groundwater aquifers where there are few piezometric wells.