When we talk about “sea level rise,” most people immediately think of melting polar ice and warming oceans. But along much of the United States’ Atlantic coast, especially in and around the Chesapeake Bay, that narrative only tells part of the story. Emerging science shows that land subsidence, the sinking or lowering of the land surface, has been and continues to be a dominant driver of relative sea level change and coastal flood risk in many regions. It is time to appreciate that the ground sinking beneath us can matter more than the ocean rising above us.
The Chesapeake Bay Story – A Legacy of Sinking Land
In the southern Chesapeake Bay region, scientists have documented persistent land subsidence since the 1940s, with measured rates between 1.1 and 4.8 millimeters per year. These amounts may sound small, but they accumulate over decades, and when combined with rising ocean levels, they explain why this part of the Atlantic coast currently exhibits some of the highest relative sea level rise rates in the United States.
In fact, new data from the U.S. Geological Survey corroborates older studies in the region, concluding that “land subsidence causes more than half of the observed relative sea level rise,” not melting ice thousands of miles away at the poles.
Subsidence happens when the Earth’s surface lowers over time. In the Chesapeake Bay area, a mixture of factors contributes to this sinking: historical groundwater pumping, aquifer compression, and natural geological adjustments after the last ice age all play roles. But the key point is this: the land itself is slipping down, and as it does, tides and flood waters appear to rise faster than they otherwise would.
A Global Perspective – Deltas Sinking Faster Than the Seas Rise
As described in a January 14, 2026 article published Nature, Global Subsidence of River Deltas, land subsidence is a global issue, in a study that spanned 29 countries “we find that contemporary subsidence surpasses absolute (geocentric) sea level rise as the dominant driver of relative sea level rise for most deltas over the twenty-first century.”
Although the Chesapeake Bay is an estuary, not a river delta, the point remains significant for coastal planners and environmental lawyers alike: relative sea level rise is a compound phenomenon, and subsidence can dominate the geologic formation that is the coastal plain abutting the Piedmont Plateau, even when global sea levels may be rising due to climate change.
Human Activity and Subsidence – Beyond Groundwater
Historically, environmental policy has linked land subsidence in the U.S. to groundwater withdrawals and extractive activities. For example, the Houston Galveston region, a frequently cited extreme case, lost more than 9 feet of land elevation over roughly 50 years due largely to intensive groundwater pumping and petroleum extraction. The community eventually changed water management: switching to surface water supplies, limiting coastal groundwater wells, and implementing aquifer recharge strategies, measures that slowed subsidence, and flood vulnerability.
But new research makes clear we have underestimated another major human influence: stormwater management practices.
While earlier flood control efforts in the 19th century focused on conveying water through pipes and beginning in the 20th century, constructing a separate sewer system dividing sanitary waste from stormwater, modern Stormwater management emerged in the U.S. in the 1970s as a regulatory response to The Clean Water Act, focusing on how rainfall runoff is conveyed, stored, and treated to prevent flooding, erosion, and water quality degradation. Historically, stormwater infrastructure (detention basins, inlets, pipes) intercepts and reroutes rainwater that had soaked into the ground.
By altering the natural hydrology of landscapes, reducing infiltration and directing water quickly to drains and outfalls, stormwater systems can lower the time water spends in soil and diminish groundwater recharge. While stormwater policy goals such as runoff reduction, and erosion control are important, we now understand that these engineered changes also modify subsurface water balances in ways that can worsen subsidence. Moreover, the misguided expansion of traditional rain water falling on the surface management to now include “pollutant treatment” has dramatically altered surface water hydrology, having the unintended consequence of exacerbating land subsidence. This is an emerging area of research at the intersection of hydrology, land use planning, and environmental law.
Defense Interests and the Real – World Costs
Recognizing the practical implications of subsidence isn’t academic. The U.S. Navy has observed subsidence rates around its key facilities that rival or exceed sea level rise itself. In the Hampton Roads region of Norfolk, Virginia, home to the largest naval base in the world, land is sinking at an estimated 0.236 inches per year, a rate roughly double local sea level rise figures. These trends exacerbate flood risk and have driven infrastructure hardening and strategic adaptations. Similarly, places like the U.S. Naval Academy in Annapolis are experiencing measurable land subsidence that worsens tidal flooding, prompting multi million dollar coastal defense measures.
At least three recent studies conducted for the U.S. Navy at both of those facilities, while not completely released to the public, conclude “land subsidence has contributed as much or more than half of the relative sea level rise measured along portions of the Chesapeake Bay (i.e., it is not melting polar ice caps).”
Measurement and Emerging Evidence
Subsidence isn’t just theorized, it’s measured. A suite of techniques, including extensometers, GPS, satellite radar interferometry, and long term leveling records provide precise data on how land elevations change over time. These methods have been deployed in critical coastal environments for decades, offering a rich dataset for lawyers, regulators, and planners who assess compliance with resilience planning laws, infrastructure standards, and hazard mitigation regulations.
It is now becoming clear that altering the rain with stormwater management is the largest single contributor to land subsidence.
Turning Data into Policy
For environmental lawyers, these scientific realities raise important questions about regulatory focus. Should coastal policy continue to prioritize sea level rise mitigation (e.g., greenhouse gas reductions), even though there is no rational basis for it, without parallel attention to subsidence causing practices (e.g., land use laws from stormwater management regulation to unduly burdensome offstreet parking requirements that result in unnecessarily large impervious areas)? Evidence reveals that, in many regions, subsidence is a more immediate and larger driver of relative sea level risk than climate driven ocean rise. Addressing subsidence calls for revisiting misguided stormwater practices and infrastructure design, alongside climate mitigation.
Final Thought
Land subsidence isn’t just an arcane geological term. It is a substantial, measurable, and often human driven contributor to coastal flood exposure. In the Chesapeake Bay and beyond, sinking ground that is land subsidence, is much more of a part of rising seas than carbon emissions.
And until policy and practice reflect that reality of land subsidence, from stormwater ordinances to offstreet parking regulations, people will continue to build sea walls, literally and figuratively, for a threat (sea level rise) while underestimating the more formidable one (land subsidence).
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