The rains hadn't stopped for days, leaving coastal waterways swollen with little capacity to handle the runoff that kept pouring into their watersheds from the historic deluge unleashed on Southeastern North Carolina by Hurricane Florence.
But it wasn't just the floodwaters coming down the river, heading toward the Atlantic, that were causing rivers to burst their banks and headaches for coastal communities. Florence had all but stalled over the Cape Fear region after making landfall at Wrightsville Beach on Sept. 14, 2018. Not only did that keep the rains falling on the already saturated ground, with upward of 30 inches drenching some inland areas before the storm finally moved inland and dissipated, but it also allowed the hurricane's winds to keep pushing water up coastal tributaries.
The result from the combination of massive quantities of rainwater draining into already full rivers and creeks and coastal storm surge was catastrophic flooding in many coastal areas.
In New Bern, more than 800 downtown businesses and homes were damaged or destroyed by flooding fueled by a 10-foot storm surge that pushed up the Neuse River from Pamlico Sound. On the Northeast Cape Fear River, the gauge at Burgaw reached 25.58 feet four days after Florence's landfall − exceeding the crest from 1999's Hurricane Floyd by more than three feet. Thousands had to evacuate, hundreds of structures were damaged or destroyed by floodwaters, and miles of highways, including long stretches of N.C. 53 and Interstate 40, had to be closed for extended periods.
Closer to Wilmington along the Cape Fear River, the flooding overwhelmed a dam at Sutton Lake, with the ensuing deluge of water washing away of chunk of nearby U.S. 421, cutting one of the last links between the Port City and inland areas. The floodwaters and storm-related power outages, which impacted 90% of New Hanover County, also resulted in more than 22 million gallons of raw sewage flowing into local waterways.
Across North Carolina, Florence was responsible for 42 deaths and more than $16.7 billion in damages. According to state figures, nearly 75,000 structures were flooded and more than 5,200 people had to be rescued from the rising waters.
Emergency officials call flooding the silent killer, because it often stealthily sneaks up on people − especially at night − without the warnings associated with the howling of hurricane-force winds or the pounding of storm-driven waves.
Now, a new modeling approach being developed by North Carolina researchers is looking to offer officials a more complete picture of the flooding threat facing coastal communities.
But even as the research aimed at understanding the risk of flooding improves, is North Carolina potentially moving in the wrong direction when it comes to protecting and enhancing its most effective natural flood-control tool?
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A new look at modeling the threat
With multiple threats from river, surface and storm surge flooding, gauging the threat facing coastal communities can be challenging − especially when the different factors mix together.
But modeling compound flooding is tricky. While there's a very good model used to measure and analyze the risk from storm surge (ADCIRC), and another computer program that models and measures the risk from riverine flooding (HEC-RAS), the two often struggle to account for impacts captured by the other.
Enter a new modeling feature under development by researchers from the Renaissance Computing Institute (RENCI), University of North Carolina-Chapel Hill (UNC), and UNC Institute of Marine Sciences (IMS). Funded through a National Oceanic and Atmospheric Administration (NOAA) grant, the project aims to develop an approach that will offer better insights into the interactions between river channels and floodplains.
"Right now, there's no single model that can handle everything," said lead researcher Dr. Shintaro Bunya, a scientist at UNC-IMS. "That is what we're trying to change."
Using the most recent topographical information and other development and watershed data along with the latest forecasting information, the idea is to provide the best picture possible of the flooding threat facing coastal communities during a storm event.
Bunya said the new model could offer emergency officials and coastal communities better and more real-time information on the risks they face. That, in turn, could help reduce the chance of communities being caught off guard during compound flooding events and improve the timing and need for evacuations.
While still in the testing stage, the model has already shown its chops during a real-world simulation of another Florence-like event along the Neuse River.
Responding to flooding concerns
Whether it was Hurricane Floyd in 1999, Hurricane Matthew in 2016, or Florence in 2018, flooding has again and again shown itself to be the biggest potential threat associated with large tropical storm systems taking aim at the Tar Heel State.
But it isn't just coastal areas of North Carolina, worried about bigger and stronger tropical systems fueled by climate change, that face a growing threat from flooding. As the increase in greenhouse gasses warms the atmosphere and modifies traditional weather patterns, forecasters predict the state could see fewer but heavier rain events. Already, parts of Western North Carolina are subject to flash flooding events from heavy rains bands or the remnants of supercharged tropical systems charging north from the Gulf Coast − threats that are likely to increase in the coming years.
Along with improved modeling and other federal-led initiatives, North Carolina is also taking steps to be proactive instead of simply reactive to the growing threat.
In 2021, the state launched the Flood Resiliency Blueprint that represents the largest statewide flood mitigation investment in state history. The initiative aims to offer a river basin-wide approach to identify projects and strategies that should be implemented to increase community resiliency to flooding.
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The move comes as not only climate change increases the risk from flooding, but the topography of certain parts of the state's Coastal Plain compounds the challenge. Last month, a research paper published in the science journal Nature found swathes of the N.C. coast is subsiding and sinking just as sea levels rise. The coastwide average rate of sinking was estimated at about 0.06 inches per year, with a maximum sinking rate of 0.16 inches per year in parts of northeastern N.C.
Then this February, Gov. Roy Cooper signed an executive order laying out an aggressive plan to conserve, restore and grow the state's natural resources, including forests, wetlands and urban treescapes. The order calls for conserving an additional 1 million acres of natural lands, with a special focus on wetlands, by 2040. The order also sets a goal of restoring or reforesting 1 million acres of state forests and wetlands, also by 2040.
The governor's focus on wetlands wasn't by accident. Wetlands, which act like giant sponges, are vital cogs in the state's environmental ecosystem that provide important wildlife habitat, sequester and store atmosphere-warming carbon, help improve water quality by filtering out pollutants, and capture and contain runoff tied to heavy rain events.
Biologists and environmentalists say their role is becoming increasingly important as North Carolina's population booms, especially in and around urban areas and along the coast, and development pressures grow. According to the U.S. Census, the state's population hit 10.84 million in 2023 and is forecast to balloon to 14 million by 2050.
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Under increased threat?
But it could be argued not all arms of state government are moving to enhance and protect wetlands.
Last year, the conservative-led U.S. Supreme Court ruled that any wetland that doesn't connect at its surface to another body of water that has federal protection shouldn't itself receive federal protection. Previously, regulators had been allowed to take a broader view that said waters can be connected in many ways, including underground.
The Sackett case decision has ramifications for North Carolina's isolated and often dry wetlands, like pocosins, because the N.C. General Assembly included language in last year's Farm Bill that says state regulators can't adopt more stringent protections than those under federal law. The bill was vetoed by Democratic Gov. Cooper, but Republican supermajorities in both chambers of the legislature overruled his veto. While federal rules are the minimum requirements, states have the option of adopting additional protections and requirements, something California often does with its environmental regulations.
During hearings on the bill, proponents of the looser wetland protections said areas that aren't wet year-round have been over regulated by the state for years. Many farmers and developers claimed the environmental community was blowing the potential impact of the rule change out of proportion, noting that the vast majority of the state's wetlands would retain their protections.
They also said the old interpretation, which added protections to things like manmade drainage ditches, was unclear and made life difficult for property owners to determine what they could and couldn't do with their land, infringing on personal property rights and potentially limiting economic opportunities.
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Millions of wetlands under threat
According to a preliminary analysis by Environmental Defense Fund, an estimated 3.6 million acres of North Carolina wetlands may no longer have federal protection. That includes up to 555,000 acres of wetlands in the Cape Fear River watershed. Nationwide, between 15 million and 90 million acres − just smaller than the size of California − might have lost protection.
Dr. Adam Gold, a researcher with EDF’s Climate Resilient Coasts and Watersheds program in North Carolina, said the double loss of federal and state protections for North Carolina's isolated and ephemeral wetlands could herald a dire future situation for many coastal communities just as the dangers from flooding in a warming world are ramping up.
"It doesn’t take a catastrophic hurricane to cause flooding impacts with the increasing impacts of climate change," Gold said. "We need wetlands to keep doing their job to help reduce that flooding threat."
While the potential impacts of the loss of millions of acres of wetlands is fairly easy to decipher, the actual impact of the Supreme Court's decision − and the subsequent move by North Carolina − is harder to determine.
That's because the court's language was so vague, Gold said, because it's a decision that's not based on science.
That's created a lot of uncertainty − one of the reasons for the large range in how many wetlands could be impacted − and leaving everyone from property owners to regulators waiting for guidance.
"It's going to take some time to work though all of this, so we're all basically just waiting at this point," Gold said, noting litigation already has been filed challenging the federal government's interpretation of the court's ruling.
But Kelly Moser, senior attorney with the Southern Environmental Law Center (SELC), said there's little doubt that wetland losses in North Carolina have increased since the Sackett decision and adoption of the state's Farm Bill as regulators wait for more direction.
She said that from August 2023 through February, developers in North Carolina asked federal regulators for guidance on whether wetlands on their property were covered by the Clean Water Act 48 times. That compares to 141 times during the same time period in 2021-22.
According to the SELC, all 48 of the recent decisions were that the wetlands didn't warrant federal protection.
David Kelly, EDF's state director for North Carolina, said the state still has time to work out how to effectively and fairly manage its wetland resources to benefit both property owners and flood-mitigation efforts.
"Or we’ll have to be prepared to make a far, far, greater investment of taxpayer dollars towards wetlands conservation and restoration along with other costlier and less beneficial flood mitigation measures as the risks and consequences of flooding grow steadily worse," he said.
Reporter Gareth McGrath can be reached at GMcGrath@Gannett.com or @GarethMcGrathSN on X/Twitter. This story was produced with financial support from the Green South Foundation and the Prentice Foundation. The USA TODAY Network maintains full editorial control of the work.
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