Sand dunes provide a first line of defense for beach communities.
But following back-to-back hurricanes, the dunes along the coastlines experienced significant damage, where its line of defense washed away.
Cheryl Hapke is a researcher at the University of South Florida College of Marine Science.
She said Hurricane Helene reshaped the Gulf Coast. And because of its erosion of the dunes, Milton had no resistance.
“There’s the likelihood that (dunes) may have stopped some of (Milton’s) water from being able to flow into the streets in the community,” Hapke said. “They were already leveled by Hurricane Helene in most areas, there was nothing to stop. There was nothing to protect.”
Now, as the water returns to the ocean, she said surge channels have formed. That’s when coastal waves erode rocky shorelines, creating narrow inlets.
“Those water levels from Milton were able to flow into the beaches and erode the beaches,” she said. “We see features on the beaches that we did not see in Helene.”
The future of beach nourishment is rebuilding dunes wider and taller to stop surges in future hurricanes, according to Hapke.
And even then, it’s important to know that beach sand is a nonrenewable resource. Hapke said when building back it’s possible people need to be less reliant on beach nourishment.
“It’s going to become more and more expensive, nourishing a beach is almost a Band-Aid in response to storms and sea levels rise,” she said.
A key difference between Helene and Milton is how they caused flooding, according to University of South Florida School of Geosciences Coastal Research Laboratory Director Ping Wang.
“Milton’s flooding is caused by rainfall,” Wang said. “Helene’s flooding is caused by the storm surge (and) caused by the ocean.”
Wang said Milton’s damage to the coastlines was not as bad as Helene’s.
“Helene caused tremendous beach and dune erosion and the damage along the coast,” he said. “Milton did not quite ’cause as much damage along the coast like the beach, it didn’t flood the Barrier Island as bad as it flooded the inland area.”
Wang said that Helene generated the largest storm surge measured in the past 80 years.
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