Hydrology

Gravity measures changes in the aquifers. It is useful for monitoring the sustainability of water supply and utilisation.
Quad Geometrics

Gravity

It is well known that the amount of ground water influences gravity. When the target is deeper, this requires a correction or will be present as noise in the data. However, hydrological information can be valuable, particularly in the large parts of the world with scarce fresh-water resources. The sensitivity of ground gravity measurements to ground water variations is high, but it is a challenge to cover large areas with microgravity data in an economic way.

Satellite measurements (GRACE) have high precision, but the lateral resolution is not better than a few hundred of kms. Such data can give a broad picture for a land or a continent, but not for practical use in smaller scale.

Jacob et al. (2010), Wilson et al. (2012), and Christiansen et al. (2011) all reported successful hydrology monitoring.

Subsidence

Subsidence can be a measure of ground water changes in areas of drought or aquifer over-exploitation (e.g. Murray and Lohman 2018).