More than half of the infrastructure in major East Coast areas including Hampton Roads is threatened by high rates of sinking land, according to new research from Virginia Tech and the U.S. Geological Survey.
The phenomenon, known as subsidence, exacerbates the growing impacts of rising sea levels and amplifies coastal regions’ exposure to critical infrastructure damage, authors wrote in a study published this week in the Proceedings of the National Academies of Sciences, titled “Slowly but surely.”
Norfolk, Chesapeake, Hampton, Portsmouth and Virginia Beach are among those most at risk, along with New York City, New Jersey and Baltimore.
“Through this study, we highlight that sinking of the land is not an intangible threat,” Virginia Tech associate professor Manoochehr Shirzaei said in a news release. “It affects you and I and everyone – it may be gradual, but the impacts are real.”
Subsidence is largely a natural process. The earth is responding to glacial forces from thousands of years ago, adjusting to the retreat of great ice sheets that once covered the surface.
At the same time, humans have withdrawn massive amounts of groundwater faster than they can be replenished, which accelerates the sinking.
The Chesapeake Bay region in particular suffers from another contributing factor called compaction. Sediments in the bay loosen and strain under the pressure of more layers over time.
Southeastern Virginia experiences one of the highest rates of subsidence on the East Coast, in some places as much as 6 millimeters per year. That’s coupled with a similarly high rate of sea level rise.
The Virginia Tech research team last year analyzed the differing rates of subsidence along the coast, revealing that Hampton Roads is sinking at about twice the rate that sea levels are rising.
Their new study homes in on threats to infrastructure in 14 states on the East Coast.
Researchers looked at things like airports, hospitals, schools, roads, railways, train stations, post offices and levees.
Between 77-99% of interstate highways along the coast and a similar percentage of primary and secondary roads are exposed to some level of subsidence, according to the research.
It also specifically mentions “a critical section of roads in Hampton and Norfolk” where sinking rates are high.
Then there’s a more surprising finding: While sinking land is widespread in coastal communities, the researchers found that it isn’t always linked to severe exposure for property and infrastructure in every place. But Hampton Roads’ risk is clear.
The researchers say it’s important for local officials to identify and monitor critical infrastructure on land that’s sinking more quickly.
