A new outlook from federal oceanographic scientists reaffirms projections that coastal towns in Delaware will see more sunny-day flooding in the future.
Sunny-day or nuisance flooding can cause public inconvenience, such as road closures, merely as a result of a high tide, with no storm in sight. It can happen during a full moon or when wind or currents change. It’s happening more often, particularly along the east coast, as a result of climate change-related sea level rise.
Lewes saw nine days of sunny-day flooding last year. Reedy Point near Delaware City saw three. But the number of flooding days Reedy Point experiences each year could rise to 100 by 2050, according to the annual high-tide flooding outlook the National Oceanic and Atmospheric Administration (NOAA) released earlier this month. By that point, Lewes could see up to 135 days of high-tide flooding per year, according to the report.
“It’s sea level rise,” said Phil Barnes of the University of Delaware’s Institute for Public Administration. “I mean, the fact that this is happening with more frequency, that’s sea level rise. This is what it looks like.”
NOAA also lists sinking land and the loss of natural coastal barriers as causes for the increase in frequency and severity of high-tide flooding.
The recent report found annual high-tide flooding frequencies are not just increasing but are accelerating at the majority of locations along the east and gulf coasts that NOAA tracks.
“By 2030, long-term projections show 7 to 15 days of high-tide flooding for coastal communities nationally,” said Nicole LeBoeuf, acting director of NOAA's National Ocean Service, during a press call Tuesday. “By 2050, that number rises to 25 to 75 days, suggesting that high-tide flood levels may become the new high tide in some locations.”
LeBoeuf says sunny-day flooding is defined as 1.75 to 2 feet above the normal high tide.
“As sea level rise continues,” she said, “damaging floods that decades ago happened only during a storm now happen more regularly even without severe weather."
“You see where this is going,” she added. “We all need to pay attention.”
Lewes is projected to see between 7 and 12 days of sunny-day flooding this year. Twenty years ago, its average was four days a year.
Barnes, who has studied coastal resiliency needs in Sussex County, says the projections in NOAA’s recent report are not detailed enough to help local officials plan for adapting to the sea level rise.
“I wouldn't know what to do with 100 days of sunny-day flooding in Lewes,” he said. “That number without context for an entire municipality has little value other than making a case that this is going to get worse.”
Barnes notes municipalities can see the increase in flooding for themselves.
"They’re experiencing it,” he said. “So I don’t think that a local official needs a dataset from NOAA to tell them that it's flooding more often and will continue to flood more often. ”
A survey the state Department of Natural Resources and Environmental Control conducted last year found more than half of Delawareans say they’ve personally observed local impacts of climate change. Forty-seven percent say they’ve personally experienced sea level rise—a 25-point increase from 2009.