“The 2018 State of High Tide Flooding and 2019 Outlook,” released by NOAA on Wednesday, showed that coastal communities experienced an average of five high-tide flooding days over the one-year period ending April 2019.
This means that coastal residents are increasingly wading through ankle deep water to get to their cars, driving longer routes to avoid flooded roads and seeing crucial infrastructure like septic tanks and stormwater systems impacted by floods.
The government agency cited El Niño and rising sea levels as reasons why “it no longer takes a strong storm or hurricane to cause flooding in many coastal areas” and warned that people living in coastal areas should expect even more in the future.
Of the 12 areas that broke records for the number of high-tide flooding days, Washington, D.C., saw 22 days of high-tide flooding; Wilmington, N.C., saw 14 days; and Annapolis and Baltimore, Md., had 12 days. Nicole LeBoeuf, the acting director of NOAA’s National Ocean Service, said a recent visit to Norfolk, Va., was “eye-opening” to how disruptive and costly high-tide flooding is to the region, reports Climate Wire.
What is high-tide flooding?
High tide flooding, sometimes referred to as “nuisance” flooding, is coastal flooding that occurs at high tide when water levels measured at NOAA tide gauges exceed heights associated with minor impacts. This kind of event does not need a hurricane or Nor’easter to cause flooding. It can occur on a calm, clear day.
High tide flooding is one of the most noticeable impacts of global sea level rise that we are experiencing today. Since 2014, NOAA has used tide gauges located across the country to assess the frequency of high tide flooding.
NOAA uses national flooding thresholds, which allows them to communicate the frequency of visible flooding that damages infrastructure. The agency’s Center for Operational Oceanographic Products and Services developed the platform based on existing flood thresholds established by the National Weather Service.
NOAA has now identified over 40 locations where high-tide flooding trends reveal “significant acceleration” along the West and East coasts. These locations will soon see coastal flooding events become a “chronic rather than sporadic” problem.
“Once communities realize they are susceptible to high tide flooding, they need to begin to address the impacts, which can become chronic rather quickly,” William Sweet, an oceanographer at NOAA’s Center for Operational Oceanographic Products and Services and lead author of the report, said in a statement, according to CNN.
From May 2019 to April 2020, high tide flooding will occur about twice as often as levels typically observed in 2000. El Niño conditions that are predicted to persist through 2019 are a factor for the increase, along with continued sea level rise, according to the NOAA report.
