Coastal flooding in US will continue to increase as seas rise, report says – USA TODAY

Not all flood alerts are the same. Here's what you should take seriously. USA TODAY

It doesn't take a storm to inundate the coast with potentially ruinous floodwaters.

"Nuisance" or "sunny day" high-tide flooding is becoming more commonplace in the U.S., and a federal report released Tuesday by the National Oceanic and Atmospheric Administration warns that such flooding will worsen in the decades to come as seas continue to rise.

Americas coastal communities and their economies are suffering from the effects of high-tide flooding, and its only going to increase in the future, said Nicole LeBoeuf, acting director of NOAAs National Ocean Service.

As sea-level rise continues, damaging floods that decades ago happened only during a storm now happen more regularly, such as during a full-moon tide or with a change in prevailing winds or currents, according to NOAA.

Although not mentioned in the report Tuesday, seas are rising in part because of climate change: According to an online NOAA fact sheet, "The two major causes of global sea level rise are thermal expansion caused by warming of the ocean (since water expands as it warms) and increased melting of land-based ice, such as glaciers and ice sheets."

In a call with reporters Tuesday, LeBoeuf saidthat "climate change and carbon emissions are a factor at play when we look at how tides are rising.

In 2019 alone, 19 locations along the east coast and Gulf coast set or tied records where rapidly increasing trends in high-tide flooding have emerged, NOAA said.

Evidence of a rapid increase in sea-level rise related flooding started to emerge about two decades ago, and now is very clear, the report said. NOAAs National Weather Service is issuing record numbers of watches (and) warnings for coastal flooding. This will become the new normal unless coastal flood mitigation strategies are implemented or enhanced.

Last year, the Southeast saw a threefold increase in flooding days compared to 2000. For example, Charleston, S.C., had 13 days where flooding reached damaging levels, compared to the two days that were typical in 2000.

Rob Kramer removes debris from a drain as tidal flooding inundated many downtown streets in Charleston, S.C., on Oct. 27, 2015, in Charleston, S.C. Just weeks after historic rains drenched the state, more flooding along the South Carolina coast brought another round of astronomical high tides often called king tides.(Photo: Paul Zoeller, AP)

And along the western Gulf coast, percentage increases were the highest, greater than fivefold. In Texas, Sabine Pass and Corpus Christi had 21 and 18 flooding days in 2019, and in 2000 those locations would typically only experience about one and three days, respectively.

"As a Chesapeake Bay resident, I see the flooding firsthand, and it is getting worse," said William Sweet, a NOAA oceanographer with the National Ocean Service and lead author of the report. "Records seem to be set every year. Communities are straddled with this growing problem."

By 2030, long-term projections show seven to 15 days of high-tide flooding for coastal communities nationally. By 2050, it rises to 25 to 75 days, suggesting high-tide flood levels may become the new high tide.

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Coastal flooding in US will continue to increase as seas rise, report says - USA TODAY