ISLE OF PALMS — The city has stepped-up monitoring of beach erosion near Breach Inlet because the dunes in that area are seriously damaged.
“It’s a great concern,” said Mayor Dick Cronin.
The scarred shoreline is particularly noticeable between 1st and 3rd avenues, but it extends up to 5th Avenue.
“If it keeps eroding and breaks through the primary dune then we have a problem,” Cronin said.
From September 2010 to November 2012, the IOP beach from Breach Inlet to 6th Avenue lost 122,400 cubic yards of sand, according to a report prepared by consultant Coastal Science & Engineering.
The amount of eroded beach would fill more than 10,000 standard-sized dump trucks.
An estimated 58,000 cubic yards of sand was lost in the same section of beach in the year leading up to July of 2013, CS&E reported.
The changes have not gone unnoticed by locals. Erosion has created cliff-like escarpments where dunes once stood.
“The ocean seems higher at this end,” said Ted Lamm, who was visiting his mother at her beachfront home.
Council recently authorized $20,800 for CS&E to more closely monitor the erosion. That option was picked over more costly measures that would move the city closer to an engineered solution to the problem.
Based on historical data, experts think the sand lost on the beach near Breach Inlet will return over time, but exactly when that will happen is unknown.
“We feel like the beach is going to come back naturally,” said Steve Traynum, a CS&E coastal scientist.
From September 2009 to March 2010, the beach from 6th Avenue to Breach Inlet gained 42,000 cubic yards of sand, according to CS&E.
The consultant reported that changes to the inlet have caused the usual north-to-south offshore flow of sand to bypass the south end of IOP. That means a source of sand to replenish the beach has been lost.
A new, secondary inlet channel that runs along the IOP beach and growing offshore shoals are contributing to the erosion, CS&E says.
“It’s a combination of the channel and an overall build-up of the shoals on the seaward side of Breach Inlet,” Traynum said.
“The channel is having an immediate impact to the beach near 1st and 2nd avenues, while the larger-scale build-up of the shoals is what is likely forcing the channel closer to the beach,” he said in an e-mail.
One option presented to council, an inlet realignment project, would push sand back to IOP. But for now that is not being pursued.
Erosion on IOP near Breach Inlet is unusual because historically the inlet area has been considered the sand-rich end of the island. When Hurricane Sandy passed offshore in late October 2012, high surf from the storm was a contributing factor to significant dune erosion near the inlet.
Council authorized the erosion monitoring effort after also considering whether to spend $50,000 to study the options for a fix and the probable cost of construction. Another option evaluated was spending up to $250,000 to do the engineering work necessary to secure government permits for a beach repair project, said City Administrator Linda Tucker.
IOP also has battled erosion from 53rd Avenue to Dewees Inlet, where a $10 million beach nourishment project was done in 2008. It was financed largely by Wild Dunes property owners, with tax money paying $3 million.
Before the project could get started, erosion damaged the 18th hole of a Wild Dunes golf course and waves washed into a carport for nearby condominiums. The year before, tens of thousands of sandbags that shored up eight beach-front properties and the resort’s Links course washed away in storm tides — littering the coast and marshes for miles.
In contrast to IOP’s erosion battles, Sullivan’s Island has grown shoreline because of the effect of the Charleston Harbor jetties, which block the natural north-to-south flow of sand and cause it to stack up at the harbor end of the island.
Sullivan’s has so much new beach that it has developed a management plan for the nearly 200 acres of new shoreline.
The jetties decrease sand flow to Folly Beach, where a $20 million beach nourishment project is planned. Dunes that protected front beach homes on the east end of Folly are about gone, and in some areas the shoreline is within 50 feet of East Ashley Avenue.
Erosion at the Isle of Palms near Breach Inlet has damaged dunes protecting homes. The city has stepped up monitoring of the area.×
Sand dunes have been eroded at the Isle of Palms near Breach Inlet. The city has stepped up monitoring of the area.×
A new channel at Breach Inlet shown in this aerial photograph has contributed to increased erosion of dunes at nearby homes on Isle of Palms.×
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