NOAA: ‘nuisance flooding’ on the rise with sea level

Much of the US is experiencing the effects of rising sea levels with an increase—especially along the East Cost—in “nuisance flooding.”

According to a new NOAA technical report by scientists at the agency’s Center for Operational Oceanographic Products and Services (CO-OPS), Annapolis and Baltimore, Md. have seen the highest percent increase in nuisance-level flooding since the 1960s. (925 percent and 922 percent, respectively). New Jersey’s Atlantic City (682 percent increase) and Sandy Hook (626 percent) are also in the top five, along with Philadelphia (650 percent). Event frequencies are accelerating, reports NOAA.

“As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding,” said William Sweet, oceanographer at CO-OPS and the report’s lead author, in a statement. “Flooding now occurs with high tides in many locations due to climate-related sea level rise, land subsidence and the loss of natural barriers.

“The effects of rising sea levels along most of the continental U.S. coastline are only going to become more noticeable and much more severe in the coming decades, probably more so than any other climate-change related factor.”

Nuisance flooding is defined as a daily rise in water level above the minor-flooding threshold set by NOAA’s National Weather Service. This type of flooding can overwhelm stormwater drainage, close coastal roads and deteriorate infrastructure due to the corrosiveness of salt water.

Cities such as Charleston, SC, Washington DC and San Francisco are also on NOAA’s list of places experiencing the highest percentage increase in nuisance flooding days.

“In 1950, such events would have the probability of recurring every couple of years, whereas today, they occur so frequently due to decades of [sea level rise] that they are no longer classified as an extreme event,” according to the report from NOAA, which has been measuring water levels around the US for more than a century.