The last time a hurricane reached the Grand Strand, it obliterated North Myrtle Beach’s sand dunes and ripped the Sea Cabin Pier in Cherry Grove in half.
That was just two years ago.
Repairs after Hurricane Isaias, which was “only” a Category 1 storm, cost millions of dollars. It wasn’t a hurricane that required major evacuations, but it was a sign of how a single storm, even one that isn’t a Hugo or a Katrina, can do massive damage to one of South Carolina’s most precious resources — the beach.
Protecting beaches is a crucial task for federal, state and local officials. Without the sand that defines the Grand Strand, Charleston’s barrier islands or Hilton Head, the state could lose billions of dollars in tourism. Anyone who grew up in South Carolina during the 1970s and 1980s can share how the near-total erosion of Folly Beach devastated that town’s economy and made it a place to avoid.
“The beaches are a very, very valuable resource for the state of South Carolina, for the country, but they’re under very significant and increasing pressures,” said Paul Gayes, executive director of Coastal Carolina University’s Center for Marine & Wetland Studies. “That’s a significant management challenge, and now the question is how long can we manage it as we have?”
In 2018, Folly Beach along with a 26-mile stretch of the Grand Strand underwent emergency beach renourishment to restore sand lost from Hurricanes Matthew, Irma and Florence. The damage was so bad that the Army Core of Engineers paid for the entire cost of renourishment. Normally, the federal entity would pay for just 65% of renourishment in the Grand Strand and 85% in Folly Beach. The remaining cost would be passed off to state and local governments.
Why do the sand dunes matter?
Sand dunes themselves are important ecological habitats for grasses and other forms of coastal wildlife, but humans have a more selfish reason for maintaining them.
Dunes protect the buildings and infrastructure that sit behind them, particularly by breaking up storm surges, Army Core of Engineers project manager Wes Wilson said.
As storms come in, they bring in particularly strong waves that sometimes have enough force to topple buildings, wash away cars and toss boats from marinas onto highways.
Sand dunes, for their part, take the first brunt of that force, Gayes said. The strength of the impact of the storm surge depends largely on how fast the waves are moving. If a dune can slow down a powerful wave by even a couple seconds, that can exponentially decrease the water’s force when it makes impact on whatever lies beyond.
“It takes a long time for a dune to recover,” he said. “It may take weeks and months, even years to build a strong, healthy dune system, but a storm can come in and remove that dune in six hours.”
The dunes are strong, but brittle. They sometimes can’t survive more than one major hit.
“If another storm comes in before it’s recovered, it’s not there to do the protective services that was there before,” Gayes said.
Protecting sand dunes and the beaches in front of them is a circular endeavor. Tropical weather and general erosion over time wash away the sand, and governments have to spend millions of dollars to put the sand back, repeatedly. The task sounds futile, but Wilson says it’s worth it.
“After a hurricane has hit, the beaches that have been renourished and have sufficient protection measures such as dunes in place, fare far better than those that have not,” Wilson said.
The process to actually put sand back can be an irritating one for homeowners and visitors unlucky enough to be at the beach when renourishment is happening.
“We always say it’s a short-term inconvenience for a long-term benefit,” Wilson said. “As the contractor’s working in front of your house for a day or two, they can be kind of loud and kind of noisy. But as soon as they move on, within a day or two, you’ve got a brand new beach in front of your home and reduce the risk of damages to not only your home, but the structures behind your home.”
What causes beaches to disappear?
There are a lot of reasons beaches erode. The most constant one is a sort of “river of sand” that is perpetually moving from north to south along the East Coast.
This movement causes some beaches to erode and others to grow, though as the sea level rises, the sand frequently disappears into the depths of the ocean, rather than flowing south to, say, Pawleys Island, Hilton Head or Florida.
“Over the long term, we are always losing sediment,” Gayes said. “That’s why we do renourishment, which is putting sand ‘back in the budget’ by artificial means.”
The more noticeable reason for beach erosion tends to be storms, experts say.
Isaias, for example, was particularly notable because of the damage its storm surges did to the low-lying sand dunes of North Myrtle Beach.
The storm surge’s strength came from both the power of the Category 1 hurricane itself but also the fact that it made landfall during the so-called “King Tides.” These appear several times a year and are known as the highest tides seen in the Grand Strand. When the King Tides reach North Myrtle Beach, particularly the Cherry Grove neighborhood, many roads flood, even without any rainfall or tropical weather.
The wind and storm surges that come with tropical storms and hurricanes break up the sand on the beaches and drag it back into the ocean, Gayes said.
Frequently, the sand will return on its own, but hurricanes can interrupt that process.
“It can move off shore enough that it won’t come back,” Gayes said.
This happened notably from 2016 to 2018, when a series of hurricanes — Matthew, Irma and Florence — tore up South Carolina’s beaches.
Their devastation was amplified by the fact that the hurricanes, particularly Matthew and Florence, were preceded by other tropical weather in the weeks leading up to them. That one-two punch left the beaches with no time to recover between storms.
“It’s not always a given storm that comes in that is the particular problem. It’s what’s happened a week or two weeks or 10 days before some of the big flooding events,” Gayes said. “If you’ve had a storm come in and kind of made the beach go away by moving material out of the upper beach and then the next storm comes in — it’s disproportionately more impactful.”
As a result, the Army Core of Engineers spent $60 million on an emergency beach renourishment spanning 26 miles of the Grand Strand and all of Folly Beach. Other parts of the state also had to do emergency renourishments, but the funding came from other sources, such as local accommodations taxes.
That renourishment required 3 million cubic yards of sand — the equivalent of 300,000 dump trucks — to be pumped from deep in the ocean onto the Grand Strand’s beaches alone.
Even a few years later, without any major storms, there is already some visible sand loss, Gayes noted. Garden City in particular, being on the edge of the renourishment project, has several blocks with at-risk structures as the ocean creeps in.
Not all storms do as much damage as Isaias, Florence, Irma and Matthew. A host of factors, from the speed at which a storm makes landfall, whether it’s a direct hit, the strength of the storm and even the direction it makes contact can all influence how badly the beaches are affected, said Victoria Oliva, a meteorologist for the National Weather Service’s Wilmington office.
“The storm surge is tied to the strength of the storm. The stronger the storm, the stronger the winds and the greater the surge,” Oliva said. “The greatest threat as far as surf goes is the stronger storms that are coming head on and pretty much coming head on for quite a while.”
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