Sep 9, 2015

2014 State of Nuisance Tidal Flooding

by
William V. Sweet and John J. Marra
,
NOAA
  • States that NOAA water level gauges document an increasing frequency of tidal flooding around much of the U.S., which is driven primarily by local relative sea level rise
  • Updates the number of days during 2014 with a “nuisance” tidal flood, which surpasses the local NOAA elevation threshold for minor impacts (e.g., road closures and diminished storm‐water drainage capability) established for emergency preparedness reasons
  • Examines conditions during 2014 at 27 long‐term gauges across the U.S. and compare to flood frequencies recorded during 2013 as well as those expected to occur in 2014 based upon continuation of annual flood trends derived over the 1950‐2013 period
  • Finds that during the 2014 meteorological year (May 2014 – Apr 2015), the mid‐Atlantic coast was most impacted
  • Finds that between Sandy Hook, NJ and Savannah, GA long‐term accelerating trends continued unabated with several locations reporting 20 or more days of flooding and an increase from 2013
  • Finds that along the West Coast (La Jolla and San Francisco) where local sea level rise has been less over the last couple decades, there were >5‐10 days of nuisance flooding, which is close to the trend‐expected values
  • Finds that less‐than‐expected flooding occurred along the Northeast Atlantic and Gulf Coasts. With the strengthening of El Niño predicted over 2015, nuisance flooding may become especially problematic along the West and East Coasts based upon historical patterns
  • Projects that—with respect to the steady continuation of the 1950‐2013 trends—nuisance flooding during 2015 will be further amplified because of El Niño‐related conditions, with a >25% increase at Sandy Hook, NJ, Atlantic City, NJ, Baltimore, MD and Wilmington, NC, a >50% increase at Lewes, DE, Washington D.C., La Jolla, CA and a 75‐125% increase at Montauk, NY, Norfolk (Sewells Point), VA and San Francisco, CA
  • Predicts this could result with the highest number of nuisance flood days on record at Sandy Hook, NJ, Lewes DE, Washington D.C. and Norfolk, VA