People flocking back to Pinellas County beaches after Hurricane Helene's wrath may find them wider in some places than they were before.
It appears that the storm surge was so massive that it completely wiped out the dunes on most of the beaches.
Hurricane Helene didn't affect the beaches like a typical storm. After Hurricane Idalia last year, what is called "scarping" left dunes with steep sides. Helene's storm surge was so powerful it appears to have flattened almost all the dunes. The sand was then deposited in beachside homes or onto Gulf Boulevard and nearby streets.
Storms like this cause extreme coastal change, said Cheryl Hapke, a professor of coastal geology at USF's College of Marine Science.
“What you probably didn't realize is how much lower they are,” she said of the appearance of the beaches. “So they basically are deflated. The dunes are completely flattened. Some of that material is pushed into the roads and streets, but some of it is pulled back by the receding waves and smeared out over the beach. You can also stir up sediment from the seabed offshore that can get pushed onto the beach during the storm ...”
What this means, she said, is there is little to no protection from high waves during the next storm.
“Dunes will rebuild themselves naturally over time, and those wide beaches will help. But that can take years,” Hapke said. “And I have a feeling that there's that sense of 'we're not safe anymore with our dunes missing' that will prompt some sort of emergency response. With no dunes there now at all, or in very few locations of the dunes left, any stormwater can just rush right in.”
Not every beach in Pinellas was affected the same way, she said.
“I did look at burial imagery for a lot of the area. And some areas like Sunset Beach really eroded. Other areas like St. Pete Beach do appear to be wider and in Upham Beach, I noticed that some of the T-groins that they have, there were a little bit more buried,” Hapke said. “I would never say that storms like these are good for beach, because now the beach is compromised because it's so flat and there's no dune to act as a defense. And so the areas landward of where the dunes used to be are really exposed to flooding should another storm come through.”
