Communities Under Water: Lessons Learned from Extreme Floods
VOLUME 29, NUMBER 4, FALL 2016
By Joey Holleman back to main story
Storm surge: “Powerful is an understatement”
Hurricane Matthew hit South Carolina with storm surge, the one variety of flooding the state had avoided in the October 2015 rain event, and that meant new lessons.
The first was that storm surge height is less important than inundation depth. Charleston Harbor registered a storm surge of just over six feet during Matthew, but that peak fortunately arrived close to low tide. The inundation depth—or height of water above local ground level—was one-to-two feet on the low-lying portions of the Charleston peninsula.
On the other hand, Matthew’s surge hit closer to high tide on Hilton Head Island, Hunting Island, and Edisto Beach, creating higher inundation levels. At Edisto, the National Weather Service reported a water line about four-feet high on a house across from the beach.
Matthew also offered a reminder of the power of surge, the wall of water created by hurricane winds and low pressure. The force pushed so much sand onto Edisto Beach’s Palmetto Boulevard it appeared the beach had moved a block or two inland.
Storm surge estimated at around nine feet took its toll on Hunting Island State Park. “The surge is real, and too often we don’t really see its impact,” says Phil Gaines, director of S.C. State Parks. “We focus on the dramatic visuals of twisted and downed trees.”
Powerful moving water rushed over dunes and through Hunting Island’s oceanfront campground, tearing the door off a bathroom and depositing sand so deep it nearly covered the toilet seats.
“Powerful is an understatement,” Gaines says. “Evacuation of staff and visitors is imperative.”
The park staff knew what to do from past hurricanes, but Matthew impressed the message on a new generation. Park employees left ahead of the storm, and they had equipment secure and ready to get back once the water began to subside, Gaines says. Three weeks after Matthew, all of the parks—with the exception of Hunting Island and the oceanfront campground at Edisto Beach—were open again.
back to main story
Last updated: 1/18/2017 10:39:40 AM