Yes, satellites can help estimate large-scale groundwater changes indirectly. GRACE-type missions detect changes in gravity caused by redistributed mass; they do not photograph an underground aquifer or select an exact drilling point.
Water changes a region’s mass
Gravity depends on mass. When a region gains or loses substantial water, its gravitational signal changes slightly. Twin GRACE spacecraft measured changing separation as they traveled through Earth’s gravity field. Combining observations over time produces regional information about moving mass. [1]
Total water is not automatically groundwater
A gravity signal can include surface water, soil moisture, snow, ice and water stored underground. Scientists must account for other components to estimate groundwater change. NASA’s California analyses show how satellite measurements can inform groundwater assessment in a broad region. [2]
Why this cannot choose a backyard well
Imagine weighing a closed box that contains several containers. A lower total weight tells you something left the box, but not which small container lost it. The satellite problem is more complex, but the analogy explains why additional measurements and models are needed. Regional mass change is not a map of individual water-bearing fractures.
The useful role is monitoring change
The method helps assess patterns that are difficult to see from scattered wells alone. Ground observations remain important for water levels, aquifer properties and local decisions. A claim that a satellite image guarantees water at a precise depth needs much more evidence than a regional gravity trend. Satellite hydrology is valuable precisely when its spatial and interpretive limits are respected.
Gravity and radar: two different indirect methods
GRACE is not the only satellite approach relevant to groundwater. Stanford researchers used interferometric synthetic aperture radar, or InSAR, to measure changes in ground-surface elevation and relate those changes to water levels in studied confined aquifers. Their study compared inferred water levels with monitoring wells in Colorado’s San Luis Valley. [3]
| Method | Directly observed signal | Needed interpretation |
|---|---|---|
| GRACE-type satellite gravity | Changes associated with redistributed mass | Separate water-storage components to estimate regional groundwater change. |
| InSAR satellite radar | Surface displacement between observations | Relate deformation to aquifer behavior and check it against ground data. |
| Monitoring well | Water level at a particular observation point | Use aquifer properties and additional observations to understand stored volume. |
Neither satellite method is an underground photograph. InSAR can provide a different kind of spatial information from gravity monitoring, but the connection between deformation and groundwater depends on local conditions. A map of estimated change is therefore not interchangeable with a guarantee that a new borehole will produce water.
Frequently asked questions
Can GRACE see water through rock?
It measures gravity effects, rather than taking a photograph through rock.
Can it locate the best place for a well?
Regional gravity data cannot alone select an exact drilling site.
Are well measurements still needed?
Yes. They provide local information and help check regional estimates.
Keep exploring
How does gps know your location. How do satellites stay in orbit.
Sources and evidence
- NASA JPL — GRACE-FO science ↗
Mass redistribution and twin-satellite gravity measurements.
- NASA JPL — California groundwater loss ↗
Regional groundwater interpretation of GRACE observations.
- Stanford — Radar observations and groundwater ↗
InSAR surface deformation compared with groundwater levels in confined aquifers.
Sources consulted: 12 October 2026. Written with AI assistance and checked against the linked references; not independently reviewed by a subject specialist. Sources do not endorse this article. See our editorial policy.
Revision: Expanded with a comparison table or worked example to clarify common misunderstandings; original URL retained.