Mid-Atlantic
The Chesapeake Bay Bridge.

VA - VA Tech Study: Sinking Ground in Parts of Chesapeake Bay Area Will Worsen Flooding

New research by Virginia Tech scientists shows that sections of the Chesapeake Bay are sinking at rates of nearly a quarter an inch — or 7 millimeters — a year.

Further, up-to-date knowledge of where the ground in the Chesapeake Bay area is sinking and by how much is not included in the official planning maps that authorities use to assess the local flooding risk from rising sea levels, the researchers said.

This poses a significant challenge to present and future management efforts as it could under or overestimate flooding risk to coastal communities along the stretch of Virginia shoreline, said Manoochehr Shirzaei, an associate professor of radar remote sensing engineering and environmental security in the Department of Geoscieces, part of the Virginia Tech College of Science, and a member of the Virginia Tech National Security Institute.

The new findings from the Virginia Tech Earth Observation and Innovation Lab appear in the Journal of Geophysical Research, with scientists having measured how much the land along the Chesapeake Bay’s shoreline has sunk using interferometric imaging with synthetic aperture radar from Earth orbit to detect elevation. The latter technique can measure year-to-year changes in local ground elevation as small as a millimeter, said Sonam Futi Sherpa, a doctoral student in the Department of Geosciences and lead author of the study.

Sonam Futi Sherpa. Photo by Steven Mackay for Virginia Tech.

The study uses data from 2007-20. The researchers further estimated potential inundation through the 21st century coming from land elevation changes, sea level rise, and storm surge.

“Although we found that most of the bay is sinking by less than 2 millimeters a year, in several areas, we discovered subsidence rates of 4 to 5 millimeters per year and more,” Sherpa said.

In addition to Sherpa and Shirzaei, Chandrakantha Ojha of the Department of Earth and Environmental Sciences at the Indian Institute of Science Education and Research contributed to the study.

The region, of course, hosts the largest naval base in the world, Naval Station Norfolk, and has a dense population of more than 1.7 million people alongside wildlife, Shirzaei said. Its attraction as a tourist destination is also among the highest in the state.

Sherpa further points to Chesapeake Bay’s Hampton Roads, which includes Norfolk, Newport News, and Virginia Beach, as hot spots of land subsidence occurring at a relatively high rate, exacerbating the effects of sea level rise and storm surge. Located in the bay midway between Montross and Reedville near the Potomac River, the area is subsiding because of groundwater pumping and erosion, the study found.

New research by Virginia Tech scientists shows that sections of the Chesapeake Bay are sinking at rates of nearly a quarter an inch — or 7 millimeters — a year.


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