Flooding on Wingate-Bishops Head Road, Eastern Shore, Maryland, during a spring high tide, October 2007. (Photo by Wanda Diane Cole, for Sea Level Rise: Technical Guidance For Dorchester County, a report to the Maryland DNR Coastal Zone Management Division.)
Scientists from NOAA’s National Ocean Service have recently completed an analysis of “nuisance flooding” in 27 U.S. cities. Their report includes the number of nuisance flood days each location experienced in 2014, how nuisance flooding has changed since 1950, and how El Niño is likely to boost the number of nuisance flood days for many cities through spring 2016. (press release | full report) In this Q&A, oceanographers Billy Sweet and John Marra explain nuisance flooding and the risks it poses to U.S. cities.
Q. In a nutshell, what is nuisance flooding?
Nuisance flooding is minor, recurrent flooding that takes place at high tide. It occurs when the ocean has reached the “brim” locally. Because of sea level rise, nuisance flooding in the United States has become a “sunny day” event—not necessarily linked to storms or heavy rain.
Q. If the impacts are minor, why do we care?
During nuisance flooding, waves may overtop old seawalls, water may inundate low-lying roads, and storm-water drainage can be diminished. These impacts may not be life threatening, but they disrupt transportation, damage infrastructure, and strain city and county maintenance budgets. A nuisance flood can become a more severe problem if a local rainstorm, storm surge, or wave-overtopping event coincides with high tide.
When water levels reach the nuisance flood level, locally the ocean has reached the “brim” and minor flooding starts to occur. Impacts include overtopping of old seawalls, flooding of specific roadways and diminished storm-water drainage capability, among others. A more severe problem results if a local rainstorm, storm surge or wave overtopping event also happen concurrently during high tide.
Press link for more: William Sweet & John Marra | climate.gov