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Sea levels rise every year, increasing the risk of flooding worldwide. A study now shows that large areas on the American east coast are also slowly but surely sinking. This is also the case for densely populated cities such as New York, Baltimore and Norfolk, where ground movement not only increases the risk of flooding, but also the sometimes dilapidated infrastructure – buildings, pipes, streets, railways and runways of major airports – threatens.
“The problem is not just that the land is sinking,” said lead author of the study Leonard Ohenhen of Virginia Tech University. “The problem is that the hotspots of the land that are sinking correspond to centers with a lot of people and infrastructure.” In the journal PNAS Nexus, the scientists discuss, among other things, the major New York airports JFK and LaGuardia, where the ground is sinking more than 2 millimeters every year.
For the entire American east coast, the researchers analyzed ground movements along a 100 kilometer wide strip using radar measurements and satellites. It shows that large parts of the area are sinking by more than 2 millimeters per year, and an area of 3,700 kilometers even by more than 5 millimeters per year. In New York, Baltimore and Norfolk it is 1 to 2 millimeters per year. The causes of the movements are mainly the compaction of the subsurface, the extraction of groundwater and mining.
The sinking ground, in combination with sea level rise, currently about 4 millimeters per year, could triple the risk of flooding in certain areas within a few decades, the scientists added.