Sensors reveal a "sunny day" flooding crisis on North Carolina coast

The sun was setting in a cloudless sky when salt water crept across Canal Drive, pooling over storm drains and glinting beneath mailboxes. No hurricane. No nor’easter. Just an ordinary high tide riding on a higher sea.

On days like this, parts of Carolina Beach can feel stranded. Researchers told the town council this week that salt water reached its streets on more than 60 days over the past year. Down East, some communities now see water on the road roughly one day in three.

Those counts come from the Sunny Day Flooding Project, a multiyear collaboration of scientists who lowered sensors into storm drains and paired them with time‑lapse cameras to capture what offshore tide gauges miss: tides forcing brine backward through aging pipes, a brief rainstorm trapped behind a swollen high tide, wind piling water onto a shallow sound.

Each “flood day” is any amount of water on the roadway. Even a thin briny film, the team says, corrodes cars and asphalt, carries petrochemicals and fecal bacteria back into nearby marshes, closes roads to ambulances and delivery trucks, and catches visitors unaware.

“It’s flooding a lot more on land than we previously thought, and it’s impacting people’s daily routines,” said Katherine Anarde, a coastal engineer at North Carolina State University.

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This week’s briefing drew in part on a peer‑reviewed study published in June by Anarde and University of North Carolina planning scholar Miyuki Hino. Using one year of data from three North Carolina towns, the study found land‑based sensors recorded 26 flood days in Beaufort, 65 in Carolina Beach and 128 in Sea Level. Federal tide‑gauge thresholds often missed the majority of those events or, in some cases, overestimated them. “Our study shows that [the tide‑gauge] approach does not accurately capture how often flooding takes place or how long those floods last,” Hino said.

For longtime resident Bob Ponzony, it’s more than an inconvenience. Standing beside his canal‑side home, he grew emotional as he listed the dolphins, manatees and crabs that frequent the waterway. When the street floods, he said, “all of the pollution from the cars and the bug spray and the trash cans washes back into the harbor. We’re stewards of that body of water.”

Carolina Beach leaders are wrestling with cost. “It is an eye opener. It is devastating, because there really is no solution,” Council member Jay Healy said after the presentation. A frequently discussed bulkhead project along a vulnerable stretch would cost about $4 million for 85 properties, or roughly $47,000 per lot. Sequencing pumps, higher roads and other defenses could push the bill toward $20 million and still would not be a permanent solution. During a flood, Healy warned, an ambulance might not reach a resident in distress.

Climate change is the backdrop. Rising seas mean tides that once lapped below the curb now reach into stormwater networks built decades ago for lower water. Local modeling shared Tuesday used federal projections: roughly 3 inches of sea‑level rise by 2030, about 7 inches sometime in the 2040s or 2050s, a foot between 2050 and 2070. Tides that today stop at the edge of the pavement will, within a decade or two, cover it more deeply and more often. Flood days that are now disruptive could grow into longer closures with greater health and economic risks.

Researchers emphasize there is no single fix. In Carolina Beach, tides and wind dominate; in rural Carteret County high groundwater and clogged ditches turn modest rains into street‑blocking pools. That variability, Hino said, means “no one size fits all solution.” Instead communities can “buy time” by sequencing strategies: maintain or replace one‑way valves that fail when reeds or oysters jam them open, add targeted bulkheads, install pumps, elevate roads or in some cases consider moving infrastructure out of harm’s way. 

Frequent tidal flooding matters has an inland impact as well. Vacationers from the Triangle and the Piedmont pour money into coastal economies. As flood days multiply, public dollars from across North Carolina are likely to help fund defenses or emergency response. More accurate measurements, the scientists argue, give towns evidence to compete for those resources and to weigh which investments protect both ecosystems and property values.

“With many things related to climate change, the best time to act was maybe 10 or 20 or 30 years ago, but the next best time to act is today,” Hino said. “You have a problem now, and you have got to start somewhere.”

For now the water keeps rising, one sunny day at a time.