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High-tide flooding happens twice as often in coastal areas as it did 30 years ago due to rising sea levels, according to a new report from the National Oceanic and Atmospheric Administration.
High-tide flooding happens twice as often in coastal areas as it did 30 years ago due to rising sea levels, and flood records are likely to be broken in the coming year, according to a new report from the National Oceanic and Atmospheric Administration.
“Breaking of annual flood records is to be expected next year and for decades to come as sea levels rise, and likely at an accelerated rate,” says the report released Wednesday, which details high-tide flooding in 2017 and forecasts a general outlook for 2018.
NOAA's findings look at the 2017 and 2018 meteorological years, which run from May 2017 to April 2018 and May 2018 to April 2019, respectively.
High-tide flooding, sometimes called sunny-day or nuisance flooding, which can swamp roads and storm drains, tied or set records last year at more than a quarter of the 98 coastal locations monitored by the federal agency.
Regionally, high-tide flooding was most common along the northeast Atlantic and western Gulf of Mexico due to active nor’easter and hurricane seasons. Cities most frequently affected included Boston (22 days), Atlantic City, New Jersey (22 days); Sabine Pass, Texas (23 days) and Galveston, Texas (18 days), all of which set new records for frequency of floods.
In the southern Atlantic and eastern Gulf of Mexico, new records included 14 days of flooding in Waveland, Mississippi and six days each in Fort Myers, Florida; Cedar Key, Florida and Dauphin Island, Alabama.
“Along the east coast, a troublesome trend continues,” William Sweet, an oceanographer at NOAA’s Center for Operational Oceanographic Products and Services, said on a call about the report. “Annual flood days are increasing at an accelerated rate. In particular, along the southeast Atlantic coast—from Norfolk southward—is experiencing the fastest rate of increase in flooding, a more than 150 percent increase since 2000 alone.”
NOAA expects that more records will shatter in the coming year, though the severity of flooding will vary from region to region and can be difficult to predict due to erratic weather patterns, including a climate cycle in the Pacific Ocean known as El Niño.
Conditions are favorable for El Niño, though it’s not officially predicted to occur, Sweet said.
“Typically, when it develops, we see higher flood frequency in about half of the locations we examine, particularly along the west and east coasts,” he said. “As a whole, flood frequencies in 2018 are predicted to be upwards of about 60 percent higher across U.S. coastlines as compared to a baseline of about 20 years ago, or the year 2000.”
But rising sea levels mean that cities are already feeling the impacts of increased flooding, even without extreme weather events.
“Now, more common high tides and wind events are causing street-level flooding,” Sweet said.
Local responses to these flood events often include street closures and other temporary measures to try to keep water from getting into buildings, such as sandbags or pumps.
“There’s a cost, and it’s important for communities to know what to expect,” Sweet said. “And that’s why we’re doing this.”
Endnote: Kate Elizabeth Queram is a Staff Correspondent for Government Executive’s Route Fifty and is based in Washington, D.C.
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