Expert says replacing dunes is Ocean City’s best protection against future storms – Shore News Today

Expert says replacing dunes is Ocean City’s best protection against future storms

Written by Cindy Nevitt

Thursday, February 28, 2013 12:00 am

Cindy Nevitt / Moving sand from beaches with an excess to those with a dearth is a cost-effective way of maintaining the profile of the shoreline.

OCEAN CITY — What nature takes decades to build and man needs years to imitate, Sandy took away in hours.

In a presentation before the Ocean City Environmental Commission Tuesday, Feb. 26 at the Bayside Center, two longtime employees of Stockton’s Coastal Research Center showed how the Oct. 29 super storm caused hundreds of feet of dune and shoreline retreat, undoing 25 years of beach replenishment projects in the city’s north end. The storm also took a heavy toll in the south end of town, where no federal beach fills have ever taken place.

Crist Robine, a coastal geologist and geotechnical coordinator at the center, and Steven Hafner, assistant director of the center at The Richard Stockton College of New Jersey, discussed the effects of Sandy on seven profile sites: Garden Road and Sixth, 20th, 34th, 56th and 59th streets, and Corson’s Inlet.

“The dune system is the most important feature on barrier islands for providing storm protection and natural habitat,” Hafner said. “Artificial dunes, where the sand is bulldozed into place and fenced and vegetated, are not as strong as natural dunes because they lack the root structure, but it’s not as long a process as when dunes accumulate naturally.”

Robine said Sandy caused 125 feet of dune retreat on the beach at Garden Road; a shoreline retreat of nearly 200 feet at Sixth Street; 155 feet of shoreline retreat at 59th Street, and 160 feet of dune retreat at Corson’s Inlet. The storm also caused “substantial damage and dune failure” at 56th Street, he said.

Only the beaches in the center of town, where sand from six north-end beach replenishment projects has drifted and accumulated to such an extent that the shoreline has advanced by as much as 500 feet, were able to weather Sandy’s assault, Robine said. The beach at 26th Street, he said, was “relatively unscathed” and the dunes at 34th Street “remained intact.”

As anti-dune sentiment from homeowners more concerned about their views than their properties’ protection has compromised the dune systems in many coastal towns, Hafner said barrier islands must work to re-establish dunes in order to protect themselves against future storms. This can best be accomplished by planting an 80/20 or 90/10 ratio of two sand-tolerant and disease-resistant grasses 8 to 10 inches deep in a zigzag pattern along a fence, and by eliminating access paths through the dunes. Such pathways allow water driven by Sandy-sized storms easy access through the dunes into homes and streets.

In addition to building and strengthening the dunes, beaches must be widened.

“The ultimate goal is to absorb the wave as it moves across the beach before it reaches the dune,” Hafner said.

Beach replenishments are one method of widening the strands, but they are costly and it can take three years to put the funding in place for such projects. A method called sand backpassing, where sand is trucked from beaches with an excess of sand to beaches with a need for sand, is an economical way of “recycling sand that is already in the system,” Hafner said. “We encourage communities to use trucks because it’s cheaper.”

“I think we’re going to see a lot more of it in the next decade, mainly of necessity,” he said. “Not as a replenishment project because there’s not enough sand there for that, but as maintenance.”

To further help shore towns protect themselves against storms, the geologists said the Coastal Research Center expects to complete a Dune Susceptibility Model for Cape May County by summer. The model will pinpoint each island’s deficiencies, allowing the towns to concentrate their efforts on shoring up those areas.