Sea-level study brings both good news and bad news to localities across Hampton Roads

A new study of local sea-level trends by researchers at the Virginia Institute of Marine Science brings both good and bad news to localities concerned with coastal inundation and flooding along the shores of the Chesapeake Bay.

John Boon, the study’s lead author, says the good news is that “absolute sea level in the Chesapeake Bay is rising only about half as fast as the global average rise rate.” The bad news, says Boon, is that “local subsidence more than makes up for it.”

Boon, an emeritus faculty member at VIMS, has previously warned of the long-term impacts of sea-level rise in Hampton Roads, particularly in light of the increased likelihood of coastal flooding during hurricanes and nor’easters.

In their report, Boon and co-authors, VIMS Professor John Brubaker and Assistant Research Scientist David Forrest, stress the distinction between absolute sea level—a measure of the volume and mass of ocean water, as compared to relative sea level—the level of the ocean surface measured relative to land (and more specifically a tide gauge).

The authors note that for the Chesapeake Bay, relatively moderate rates of absolute sea-level rise, when combined with locally high rates of land subsidence and an increasing coastal population, add up to a significant and growing threat. 

They call for continued operation of the local tide gauge network and addition of new mapping tools such as LIDAR to aid in smarter coastal planning and improved emergency-response measures.

The VIMS study was funded by the Norfolk District of the U.S Army Corps of Engineers and reviewed by officials with the National Oceanic and Atmospheric Administration (NOAA) and the Maryland Geological Survey.i