Ground subsidence in the Houston–Galveston region
Groundwater withdrawal caused up to roughly 3 meters of land subsidence across the greater Houston–Galveston area during the 20th century. Texas created the Harris–Galveston Subsidence District in 1975 to regulate withdrawal, and USGS monitoring documents continued local subsidence in the region.
What is documented here
The Houston–Galveston region is one of the most thoroughly documented subsidence areas in the United States. Decades of groundwater pumping compacted the clay-rich aquifer system under the region. In places, the land surface dropped as much as three meters over the 20th century — enough to permanently submerge shoreline land along Galveston Bay. The problem was serious enough that Texas created a dedicated regulatory agency, the Harris–Galveston Subsidence District, in 1975.
Regulation slowed subsidence dramatically in the areas that converted to surface water. But the story is not over: USGS and District monitoring documents continued subsidence where groundwater use remains high, particularly toward the north and west. Rates vary from neighborhood to neighborhood, so regional averages say little about a specific site. The ground under one facility can behave very differently from ground two miles away.
For anyone who designs foundations, routes infrastructure, or prices risk here, the practical question is not whether the region subsided — it did. The question is what the ground under a specific parcel did recently. The public Sentinel-1 radar archive can answer that question at screening level, with no commissioned survey.
What the satellite archive holds here
The public Sentinel-1 radar archive, sampled at a representative point in this region. These numbers describe measurement availability — how often the satellites pass, and over what period — not ground movement. We compute movement per site, after the feasibility check.
- Radar acquisitions
- 264
- Revisit
- ~12 days
- Observed span
- 2022-01 → 2026-06
- Satellite tracks
- 3
Coverage stats as of 2026-07-14 · full Sentinel-1 archive extends back to 2015
What satellite radar can — and cannot — tell you
It can
- — Reconstruct a millimeter-scale movement history for stable radar reflectors (rooftops, pavement, rock, bare ground) on a specific site, from archive data
- — Show if the movement slows, stays steady, or accelerates — the trend shape that matters for decisions
- — Give you a dated record of what the ground did before a purchase, a design, or a dispute
It cannot
- — Measure surfaces that change between passes: dense vegetation, active construction, water
- — Replace geotechnical instrumentation, borings, or engineering judgment — it shows you where to look, not how to design
- — Tell you why the ground moves — it documents that it moves and how fast, as an input to the engineer who determines why
The honest economics: a commissioned InSAR study typically costs $10,000–30,000 and takes weeks. A self-serve report on one site costs $749, one time. The feasibility check before it is free — if the satellites cannot measure the site reliably, you pay nothing, and we say so.
Common questions
Is Houston still sinking?
Yes — parts of it. Regulation largely stopped the historic subsidence in areas that switched to surface water. But USGS and Harris–Galveston Subsidence District monitoring documents continued subsidence in parts of the metropolitan area, particularly to the north and west. Rates vary strongly from place to place.
How do I find out if a specific site in the Houston area is affected?
Public monitoring covers the region with borehole extensometers and GPS stations at specific locations, and those locations can be far from your site. Satellite radar (InSAR) reads any single site against the Sentinel-1 archive and produces a site-specific movement history at screening grade — a start point for engineering judgment, not a replacement for it.
What data does this page's coverage summary come from?
The coverage statistics describe what the public Sentinel-1 radar archive holds over this region — how many satellite passes, how often, and over what period. They describe measurement availability, not ground movement. We compute movement per site, after the feasibility check.
Check a site in the Texas region
Draw your site, and you get a free feasibility report from the Sentinel-1 radar archive in about one minute. It tells you how many passes cover the site, how often, over what period — and if the satellites can measure it at all. If they cannot, the report says so.
Check your site freeTelluric readings come from satellite radar and are screening-grade: use them to decide where to inspect. They do not replace geotechnical instrumentation or engineering judgment. Read the methodology.