NOAA: High-tide flooding expected to occur for years to come

Published: Aug. 2, 2022 at 11:35 AM EDT
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High-tide flooding will continue to be a threat to coastal communities for years to come, NOAA announced during a media briefing held Tuesday.

The phenomenon occurs when tides reach anywhere from 1.75 to 2 feet above the daily average high tide and start spilling onto streets or bubbling up from storm drains.

NOAA said that coastal communities in three locations along the Atlantic and Pacific coasts saw record high-tide flooding last year.

It is a trend that the agency expects will continue into 2023 and beyond without improved flood defense.

However, they expect fewer of these flooding events than last year thanks to La Niña and the moon being in a cycle where it's further from Earth.

But zeroing in on South Florida, projections could look higher than in 2021.

For example, Miami had zero high-tide flooding events last year but three to six are projected in 2022. Port Canaveral in Central Florida had six of these events last year but eight to 14 are projected this year.

NOAA's projections show that these flooding events are expected to dramatically increase in the next 50 years with up to 60 occurrences each year in Miami and 75 in Port Canaveral.

The newly released information documents changes in high tide flooding patterns from May 2021 to April 2022 at 97 NOAA tide gauges along the U.S. coast.

It also provides a flooding outlook for these locations through April 2023 and projections for the next several decades.

NOAA said as sea level rise continues, damaging floods that decades ago would only happen during storms now happen more regularly like during full moons.

Coastal areas of South Florida — including West Palm Beach and Delray Beach — are susceptible, often multiple times a year, to high-tide flooding, also known as king tides. The high tides often flood roads and properties along the Intracoastal Waterway.

NOAA said Tuesday that U.S. coastal communities saw a record-breaking number of high-tide flooding days in 2022 at two stations.

On the Atlantic coast, Reedy Point, Delaware, saw six high tide flooding days in 2022, one more event than 2021.

Also on the Atlantic Coast, the water level station at Springmaid Pier, South Carolina, near Myrtle Beach, tied its 2021 record with 11 high-tide flooding days observed.

Scientists said that high-tide flooding conditions along both the East and Gulf coasts are accelerating.

"The East and Gulf coasts already experience twice as many days of high-tide flooding compared to the year 2000, flooding shorelines, streets and basements and damaging critical infrastructure," Nicole LeBoeuf, director of NOAA's National Ocean Service, said.

Scientists said that high tide flooding is increasingly common due to decades of sea level rise and driven, in part, by climate change.

"High-tide flooding is becoming more common and damaging in many parts of the U.S.," NOAA administrator Rick Spinrad, Ph.D., said. "As part of NOAA's work to build a Climate-Ready Nation, we will continue to provide coastal communities with the information needed to anticipate, prepare for and respond to increasingly frequent high-tide flooding."

NOAA projects that the high-tide flood frequency between May 2022 and April 2023 will average three to seven days, the same as the previous year, but an increase from the two to six days expected between 2019 and 2020.

"As sea level rise continues, damaging floods that, decades ago, happened only during a storm, are expected to happen more regularly, such as during a full moon or with a change in prevailing winds or currents," NOAA said in a written statement.

Community leaders around Florida, including Martin County, plan roads and other infrastructure projects with sea level rise in mind.

Public Works Director Jim Gorton said MacArthur Boulevard on Hutchinson Island, for example, will be the latest flood-prone area to get a lift to protect it from rising sea levels at a cost of about $6 million.

"MacArthur Boulevard, we've got a great project out there that's going to be constructed this year that's going to elevate the roadway to take it out of the flooding. That's at the very south end right near Bathtub Beach," Gorton said. "We're also going to put in a seawall that's going to be under the dune — you're not even going to know it's there — but when we have those huge wave events where we have erosion of the beach, there's going to be a seawall to keep it from eroding all the way back to the roadway."

Protecting Florida's coastal communities will likely continue to call for many more costly projects and upgrades.

NOAA has released an outlook on coastal high-tide flooding every year since 2014.

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