– Large swaths of the US East Coast are sinking “slowly but surely.”
Densely populated cities like New York are also affected. Not only is there an increased risk of flooding, but partially dilapidated infrastructure — buildings, pipelines, roads, railways and even runways at major airports — is at risk.
Year after year, sea levels rise, increasing the risk of flooding to coastal areas and their residents around the world. Now a study shows that, at the same time, large swathes of land along the U.S. East Coast are sinking — in some cases significantly.
Densely populated cities such as New York, Baltimore and Norfolk were also affected. There, landfall not only increases the risk of flooding, but also threatens the sometimes dilapidated infrastructure — buildings, pipelines, roads, railroads, and even runways at major airports.
“Land subsidence is not the only problem,” explains lead author Leonard Ohenhen of Virginia Tech University in Blacksburg. “The problem is that hotspots of sinking land overlap directly with centers of population and infrastructure.” The geographer and his colleagues give examples in the journal “PNAS Nexus» Major New York airports such as JFK and LaGuardia, where the annual reduction rate is more than two millimeters.
Along the entire US East Coast, the team evaluated ground motions over a 100-kilometer width using radar measurements from satellites for the period 2007 to 2020. The results: Large parts of the region are sinking by more than two millimeters per year, some – up to 3,700 square kilometers – by more than 5 millimeters, and in some places by more than 10 millimeters. In New York, Baltimore and Norfolk the rate is mainly one to two millimeters per year. The main causes are groundwater and mine extraction, underground compaction.
That combined with rising sea levels — currently about 4 millimeters a year — could triple the risk of flooding in some areas within a few decades, the team writes. Even in the absence of rising sea levels, continued land subsidence in some coastal areas may result in irreversible flooding and regular flooding.