Survey to determine how much sand lost to Michael

PANAMA CITY BEACH — By a preliminary scan, Hurricane Michael is thought to have siphoned off between 1 million and 2 million cubic yards of sand from Panama City Beach's shores. That’s about the carrying capacity of 60,000 to 130,000 dump trucks.

But officials are still not yet sure what the total impact will be.

Next week, coastal engineers will conduct a survey on the 18.5-mile stretch of beach. Lisa Armbruster, the beach consultant for the Bay County Tourist Development Council, said the sand will be measured every 1,000 feet, from the dunes to 50 feet of water. The data collected will be compared to the annual survey conducted in May.

It will be important to discover how far from the shore the sand was pulled, Armbruster said. If it was taken too far, it’s unlikely that the tides will bring it back. The results of the survey are expected by the end of this month.

Armbruster said the beach erosion could have been far worse, but there was about four-and-a-half feet of storm surge on Panama City Beach during the storm.

“We were very lucky to have been just west of the eyewall,” she said.

The most recent beach renourishment — a $14.5 million project that scattered 840,000 cubic yards of sand over 3.5 miles last May — played a big role in the beach’s response to the storm.

"The beach performed very well,” she said.

Hurricane Michael was a living lesson for Jaap Nienhuis’ students. Nienhuis teaches courses on coastal change at Florida State University. While his curriculum discusses how things like sea level rise and tidal motions can shape coastlines, a hurricane’s effect on coastlines also came up this semester because of Hurricanes Florence and Michael.

They saw videos and images of Florence, which slammed the Carolinas in September. But Michael hit right in their backyard.

“It’s good to see firsthand what a hurricane can do in different places,” Nienhuis said.

His class took a field trip recently to Alligator Point and Mashes Sands, about 80 miles east of Mexico Beach.

Mashes Sands is a natural system with little development. Nienhuis said that although there was erosion there after Hurricane Michael, natural systems like barrier islands, mangrove forests and reefs are preferable defenses.

“Natural coasts tend to be gently sloping and relatively flat. There’s a lot of space for the waves to move around and decrease in their power, and a lot of space for plants to grow and attenuate waves,” he said.

On the other hand, Alligator Point is developed with hardened shorelines such as sea walls, which can be a first defense against long-term beach erosion but can “increase exposure” in a severe storm setting, he said. When the force of a strong wave is suddenly halted by a seawall, it could cause the wall to crumble and create more hazards than just flooding. Houses and roads were hit hard.

“Basically, that has allowed waves to be more impactful in the beach environment,” Nienhuis said.

Beach renourishment is an erosion control that acts like a natural system would, but it can be a costly fix that would have to be repeated every five or 10 years. When planning for beach erosion, Nienhuis said it’s important to look to the past to see what will happen in the future.

“If the coast is naturally eroding, hurricane impacts will be severe,” he said.

Hannah Morse is a reporter for The Palm Beach  Post.