Land Subsidence and Groundwater Monitoring
We use satellite InSAR to map land subsidence across entire regions - from aquifer depletion under farmland and cities to natural ground settlement. Our work reveals where the ground is sinking, how fast, and how the pattern has changed over years, across areas far too large for ground surveys.
Where InSAR Adds Value
| Situation | What satellite InSAR provides |
|---|---|
| Pumping-induced subsidence | Detect basin-wide sinking |
| Seasonal groundwater change | Separate the recoverable elastic response |
| Long-term aquifer loss | Identify permanent, inelastic compaction |
| Sinkhole risk in karst terrain | Detect slow precursor deformation |
Groundwater Extraction and Aquifer Depletion Subsidence
When water is pumped from an aquifer faster than it recharges, the fine-grained sediments between the water-bearing layers compact and the surface sinks - often across tens or hundreds of kilometres, and frequently over farmland and vegetated terrain where conventional surveys are sparse. Groundwater withdrawal is the single largest cause of land subsidence worldwide, and much of it is permanent: as the pore space collapses, the aquifer loses storage capacity that does not return even when water levels recover. Independent country-wide InSAR studies have shown how widespread this permanent, inelastic depletion has become. Satellite InSAR is particularly well suited to this wide-area, regional subsidence. It measures the full footprint of a sinking basin, separates the fastest-subsiding ground from stable ground, and tracks how the pattern responds to drought, pumping, and recovery over many years.
The record also distinguishes two behaviours that matter for management. Seasonal rise and fall, as aquifers charge and discharge, is largely elastic and recoverable; a steady long-term downward trend signals inelastic compaction and permanent storage loss. Being able to see both in the same time series makes InSAR a practical tool for groundwater management, managed aquifer recharge verification, and documenting subsidence hazard at a regional scale. Our published work includes InSAR analysis of ground deformation from natural-resource and groundwater activity in the Western Canada Sedimentary Basin and three-dimensional surface-velocity mapping of the Cerro Prieto basin in Mexico.
Natural Ground Subsidence
Not all subsidence is driven by pumping. Ground settles through the natural compaction and oxidation of soft or organic soils such as peat, through hydrocompaction of loosely deposited sediments when they are first wetted, and through the dissolution of soluble rock that produces sinkholes in karst terrain. These movements can be slow and easy to miss until they affect buildings, roads, or utilities - or, in the case of karst, appear suddenly. Satellite InSAR provides wide-area screening for natural ground settlement, showing where movement is concentrated and, over karst, where slow precursor sagging may precede collapse. Because it needs no instruments, it supports hazard mapping in areas where no ground network exists.
Subsidence from Industrial Activity
Subsidence is also caused by resource extraction and underground operations. We cover these on dedicated pages: surface settlement over mining is addressed under mining ground deformation monitoring, and reservoir and production-related subsidence under oil and gas ground deformation monitoring. The same satellite measurements underpin all of them - the difference is the setting and the questions being asked.
What a Subsidence Program Delivers
A subsidence program delivers a basin-wide velocity map showing the rate of settlement across the whole area of interest; a displacement time series for every measurement point, so movement can be read at an individual well, town, or structure; a separation of seasonal from long-term signal; and, where two viewing geometries or GNSS are available, a split into vertical and horizontal motion. Results are supplied as GIS layers for groundwater and planning workflows and can be refreshed as new radar acquisitions arrive. C-band satellites give the wide-area coverage, while L-band improves reliability over heavily vegetated ground, and the historical archive extends the picture back over past decades.
Why Satellite InSAR for Land Subsidence
Land subsidence is a wide-area problem, and satellite InSAR is built for wide areas. It needs no ground instruments, covers entire basins and municipalities at once, and draws on a multi-year archive to show how subsidence has evolved - not just a single snapshot. It performs well over rural and vegetated terrain where ground networks are thin. Because our small-baseline processing needs coherence only between nearby acquisitions, it recovers subsidence over vegetated and rural ground that persistent-scatterer-only services leave blank, and it does not rely on a dense permanent-GNSS network for calibration, so it works even where geodetic infrastructure is sparse. Our methods are grounded in peer-reviewed research published in international remote-sensing journals. Integration with GNSS to recover the broadest, longest-wavelength signals, independent validation, and regulatory reporting are available on request. Land subsidence is one of our four core monitoring services, alongside mining, landslide, and oil and gas monitoring.
Frequently Asked Questions
What causes the land subsidence InSAR can measure?
Most commonly groundwater extraction and aquifer depletion, along with natural settlement of soft or organic soils, hydrocompaction, and sinkholes in karst terrain. Subsidence from mining and oil and gas operations is covered on our dedicated pages.
How large an area can be monitored?
Whole basins, aquifers, and municipalities. Satellite InSAR is designed for regional coverage, which is its main advantage over point-based ground surveys for subsidence.
Is groundwater subsidence reversible?
Often only partly. Seasonal rise and fall of the surface is largely recoverable, but sustained overdraft compacts the aquifer permanently and reduces its storage capacity. InSAR time series show which part of the movement is seasonal and which is a permanent long-term trend.
Does it work over farmland and vegetated ground?
Yes. Distributed-scatterer and small-baseline processing, and longer-wavelength L-band radar, are chosen specifically to keep measurements reliable over rural and vegetated terrain where survey points are sparse.
Can you show how subsidence changed over time?
Yes. The multi-year satellite archive lets us reconstruct past movement and track how subsidence responds to drought, pumping, and recovery, not just measure the current rate.