Ground subsidence in Hampton Roads and the southern Chesapeake Bay
USGS documents region-wide land subsidence of roughly 1 to 5 mm per year across the southern Chesapeake Bay region. The causes are aquifer compaction from groundwater withdrawal, plus glacial isostatic adjustment. This subsidence is a major component of the highest relative sea-level rise on the US Atlantic coast.
Source: USGS Circular 1392
What is documented here
The southern Chesapeake Bay region — Hampton Roads, with its ports, naval facilities, and low-lying cities — experiences the highest rates of relative sea-level rise on the US Atlantic coast. USGS attributes roughly half of that rise to the land itself: it sinks. Two mechanisms stack. The coastal-plain aquifer system compacts after decades of groundwater withdrawal. And slow, region-wide glacial isostatic adjustment continues as the crust responds to the last ice age.
USGS Circular 1392 documents subsidence of roughly 1 to 5 millimeters per year across the region — modest rates, but persistent, uneven, and additive with rising water. The economy of the region runs on waterfront infrastructure. At a specific facility, the difference between 1 and 5 mm per year compounds into decades of design life and flood-mitigation budget.
Public monitoring here rests on a handful of extensometers, tide gauges, and GPS stations. Between those points, site-specific screening from the Sentinel-1 radar archive can document what an individual terminal, levee reach, or development parcel did — a low-cost evidence layer for planning, design, and budget requests.
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
- 270
- 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
Why is relative sea-level rise so high in Hampton Roads?
The water rises and the land sinks at the same time. USGS attributes the nation-leading relative sea-level rise of the region substantially to land subsidence — aquifer compaction plus glacial isostatic adjustment, at roughly 1–5 mm per year depending on location.
Is subsidence uniform across the region?
No. Aquifer compaction concentrates around groundwater withdrawal, and local ground conditions vary — which is why USGS reports a range rather than one number. Site-to-site differences are exactly what regional figures cannot resolve.
How does a municipality or port use screening-grade data?
As documented evidence between formal surveys: which assets sit on ground that sinks faster than the regional average, if the movement is steady or accelerates, and where to target instrumentation and budget. It is an input to engineering decisions, not a replacement for geotechnical instrumentation.
Check a site in the Virginia 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.