The Riverwalk along the Cape Fear waterfront is Wilmington’s biggest tourist attraction. It’s lined with hotels, restaurants and other businesses. But this is a tidal river, and every now and then, when the tides are at their highest, during what’s known as the “spring tide” or “king tide,” Water Street lives up to its name.

“People who have businesses on Water Street may regret the name of the street because it is all too often flooded by high tide, and that is only going to get worse,” says Larry Cahoon, a UNC Wilmington professor who has analyzed Wilmington’s tide gauge data for nearly 25 years.

Cahoon said that as sea levels rise, tides will become higher, meaning these occasional floods will occur more frequently.

Floods also plague the Battleship USS North Carolina Monument, on the other side of the river.

“It’s getting worse every day,” said Christopher Vargo, the facility’s deputy director. “When I started here 12 years ago, there would be flooding when there was a high tide, a full moon, a south wind blowing up the river, or a heavy rain. But now there’s flooding practically every high tide. It’s pretty dramatic.”

Flooding at the riverside tourist attraction has increased from 20 days per year in 2011 to 175 days in 2020, according to Data on the Battleship website.

Sea level rise is accelerating

Sea levels have risen by about a foot along the entire East Coast in the last century. And the trend is accelerating: Federal scientists predict it will rise another foot in the next three decades. The National Oceanic and Atmospheric Administration, or NOAA, said in a new report published this month that the country experienced a record number of flood days last year.

“Events like hurricanes get a lot of attention, but flooding from tidal waves is one of the most tangible impacts of long-term sea level rise. It reminds us that while we are preparing for impacts today, the United States must also prepare for a wetter future,” said Nicole LeBoeuf, director of NOAA’s National Ocean Service.

By 2050, coastal communities nationwide will see an average of 45 to 85 flood days per year, NOAA predicts. That’s ten times the current rate. And in some places, there could be even more.

“This means that Americans along our coast face disruptive and destructive flooding every four to eight days, regardless of the weather conditions,” LeBoeuf said.

According to NOAA, 34 communities nationwide broke or set records for flood days last year. They include Charleston, South Carolina (17 days); Duck on the Outer Banks (22); Atlantic City (26); and the Battery at the tip of Manhattan (24). On average, coastal communities in the Southeast experienced about 10 flood days between May 2023 and April 2024.

It’s worth noting that NOAA only counts the more severe flooding – about 2 feet above high tide. But flooding can be a problem even at lower tide levels. This means that many coastal areas experienced even more days of high tide flooding than NOAA counts.

In 2000, Wilmington averaged one day of flooding per year. In recent years, it has ranged from two to five. By 2050, it is expected to be 40 days per year, says NOAA oceanographer Wiliam Sweet. Other North Carolina communities could be even worse off. Forecasts suggest up to 110 flood days per year in Dare County and up to 70 for Emerald Isle and Beaufort.

“Decades of sea level rise are catching up with us again. In some parts of North Carolina, the water levels are frankly almost at the top,” said NOAA oceanographer William Sweet.

Two main factors contribute to sea level rise, says Larry Cahoon of UNC Wilmington.

“One is the expansion of seawater as it warms. Warm water is less dense than cold water, and when you heat it up, it literally expands,” Cahoon said. “It’s easy to demonstrate. You put a pot of water on the stove and turn the heat up, and it overflows before it boils. The other factor is that we’re melting ice much faster than we used to.”

Melting ice layers

NASA Satellite data shows Billions of tons of continental ice are lost each year, even when accounting for seasonal changes in ice area. According to NASA, this equates to a net loss of 150 billion tons per year in Antarctica and about 270 billion tons in Greenland.

This causes sea levels to rise, leading to higher tides and more flooding in coastal communities, especially during the highest tides of the year. These “spring tides” occur when the sun, Earth and moon are in a line and the moon is closest to the Earth. The next window of opportunity for these particularly high tides is mid-September.

Another factor leading to flooding is the subsidence of coastal land in some areas of the East Coast, Cahoon said.

In North Carolina, flooding occurs from Duck, Oregon Inlet and Rodanthe on the Outer Banks south to Beaufort and Wilmington and as far as Carolina Beach, where NOAA documented 60 days when streets were flooded during high tides last year – not including storm-related flooding.

“If you go to Carolina Beach and drive down what’s called Canal Drive, you’ll notice that this road has a significant amount of water in it during a spring tide. In fact, there are water protection zones designated along the road because people insist on driving through the water and the waves from the cars damage the lawn and things like that,” Cahoon said.

The flooding at Carolina Beach was the subject of a Washington Post report in JuneReporter Brady Dennis and his colleagues set up time-lapse cameras at five locations during a spring tide. Videos show the water rising over banks and levees and even coming up through sewers. Dennis spent hours watching the water rise.

“As the flood approaches, there’s this kind of wild … tipping point is a good way to describe it, when it just reaches a point where the water has nowhere to go and the sewers or groundwater come up, water rushes into low-lying areas and floods the street,” Dennis said. “I would say in 20 to 30 minutes, the street was just filled with water and was about a foot or more high.”

Flooded roads are an inconvenience for motorists and homeowners. But flooding during high tides has other long-term consequences as well. It can repeatedly result in expensive insurance claims for property owners. Pollution from chemical runoff, overflowing sewers and garbage can cause health problems. The disruptions can hurt businesses financially. And intruding salt water can damage roads, corrode pipes and equipment and threaten agriculture.

Even a few inches of water can have destructive effects, said NOAA oceanographer Analise Keeney.

“Ultimately, we need to plan for where that water is going because we know sea levels are rising. Sea levels ultimately lead to more salt water coming onto our coasts and into our infrastructure, which can destroy things over time,” Keeney said.

Solutions can be expensive. In many flood-prone communities, new construction and homes must be raised. The state’s flood insurance program may require the same for existing homes rebuilt after flooding.

In Wilmington, the USS North Carolina is closing part of its parking lot and raising the level of the rest of the site by three feet. It is part of a $4 million project called “Living Water” The work is scheduled to be completed in January. And repeated flooding has forced the Army Corps of Engineers to consider abandoning its machine yard on Eagles Island, near the Cape Fear Bridge.

Experts say more governments, businesses and homeowners in coastal areas need to think about how to adapt. Rob Moore of the Natural Resources Defense Council is calling for better planning that takes sea level rise into account.

“You have to ask yourself what the future is going to look like. And what changes do we need to make to building codes, zoning ordinances and land use regulations? How do we make the right decisions today that will last in a future that is dramatically changed by climate change,” Moore said.

Moore said that in the past, before climate change became so obvious, we humans could assume that the future would largely resemble the past and we would not need to change our behavior.

That’s no longer true, Moore said.