LOS ANGELES, Nov. 28 (Xinhua) -- The metropolitan area of Hampton Roads on the U.S. east coast is sinking at highly uneven rates, with a few trouble spots subsiding seven to 10 times faster than the area average, according to a new study led by U.S. National Aeronautics and Space Administration (NASA).
Earlier estimates had suggested that the metropolitan area is subsiding evenly, however, a new study published this month in the journal of Scientific Reports found major differences in subsidence rates appearing only a few miles apart.
According to the new study, Hampton Roads, which comprises seven cities including Naval Station Norfolk, has had one of the highest rates of relative sea-level rise on the Atlantic coast of the United States over the past century.
Researchers from NASA's Jet Propulsion Laboratory in Pasadena (JPL) and Old Dominion University (ODU) developed a new strategy to document how the land surface had changed from 2007 to 2011 and integrate the processed Synthetic Aperture Radar (SAR) measurements with Global Positioning System (GPS) observations to find the variations in subsidence.
The result was the first high-resolution estimates of vertical land movement on Hampton Roads. It has a spatial resolution of about 30 meters, whereas earlier estimates were based on data from GPS stations located 10 to 15 miles (about 16 km to 24 km) apart, according to the new findings.
This phenomenon results from a combination of land subsidence, rising sea-levels, associated with global warming over long timescales and exacerbated by shifts of ocean dynamics on shorter timescales.
Co-author Ben Hamlington from ODU said in a news release, "Information regarding subsidence should be incorporated into land use decisions and taken into consideration for future planning."
The production of the new maps was a pilot project between JPL and ODU to assess the feasibility of using space-borne SAR data to map subsidence in Hampton Roads, according to lead author David Bekaert of JPL.
He noted that these techniques developed could also be used to map subsidence at other locations. In addition, the creation of local subsidence maps are necessary for the area in oreder to help reduce increased flood risks in the future.
