Washington, D.C. and Coastal Cities: Capital Lowering Toward Ocean

As we all know, sea levels are rising. But recent research shows that Washington, D.C. is sinking toward the ocean more rapidly than some other areas, according to a study recently published in the journal GSA Today.

The District of Columbia's land is expected to fall six inches or more during the next 100 years, say researchers from the University of Vermont, U.S. Geological Survey and elsewhere, in a release.
A long-held theory existed that the Chesapeake Bay area was sinking, but their research confirms it, noted Ben DeJong, the report's lead author, in a release.

For the last 60 years, Chesapeake Bay area tide gauges have shown that sea level "is rising at twice the global average rate and faster than elsewhere on the East Coast," the University of Vermont release noted. According to an existing hypothesis, land in the area had been pushed up by the weight of a prehistoric ice sheet, and has been settling every since the sheet melted some 20,000 years ago, the release noted.

In the study, scientists drilled 70 boreholes, some as deep as 100 feet, in the coastal plain of Blackwater National Wildlife Refuge on the Chesapeake's eastern shore, said the release.

The team then examined sediment layers in the deep cores, using "a suite of techniques" to calculate the age of the sand, other rocks, and organic matter, the release confirmed.

Then they combined data with maps and made 3-D portraits of "current and previous post-glacial geological periods" in the region, stretching back millions of years, said the release.

The scientists say in the release that their model of subsidence is "bullet-proof."

Along with the existing predictions from The Intergovernmental Panel on Climate Change that global sea level will rise 1 to 3 feet by 2100 due to global warming, an extra six inches will make a difference in low-lying Washington, notes DeJong in the release.

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