Build a Cedar Island Marsh

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By Linda Cicoira Scientists are planning to build a marsh on the southern end of Cedar Island in an effort to slow movement caused by sea level rises. They also found a layer of pebbles under Chincoteague Island believed to be 300,000 years old.

“Virginia has the second fastest rate of sea level rise in the country,” Christopher Hein, an assistant professor of Virginia Institute of Maine Science (VIMS) Department of Physical Sciences, recently told Chincoteague officials who were eager to learn what could eventually happen to Chincoteague and Assateague islands and if anything can be done to slow the changes.

“The barrier islands in Virginia are more dynamic than anywhere else in the world,” Heine continued. “Their reactions are from sea level rise,” Hein said of the lands that protect the Eastern Shore.

The approach on Cedar Island is to try to naturally manage the changes. According to minutes of the meeting, Hein said he is working with an engineering firm on the cost to develop a marsh about a quarter-mile wide. Spoils from nearby channels would be used for the fill. 

“There are federal navigational channels there that need dredging and non-federal channels that local boaters and the Eastern Shore Navigable Waters Committee want to dredge,” he said.

Cedar Island was divided into lots in the 1980s and sold to those dreaming of a private paradise. But the houses that were built there were washed away.

“It has moved 30 feet in the past 30 years,” Hein said. “If they’re hit by a big storm maybe it will move 50 feet,” he speculated. “The average of the entire system it is about 25 feet over 30 years …  A beach on a barrier island can erode, losing sand and become narrower.”

“Once it gets narrow enough, the same storm that used to take sand away, can go up and over the island and push sand to the back side to help itself stay above water,” he continued. “It’s island cannibalism reusing its own sand to help stay above water.”

Hein referred to Ocean City, Md. He stated “because of the private and public infrastructure they shouldn’t be moving anywhere … when you have dense development with all the houses and then try to have an over-wash where the waves throw sand, those houses stop the waves and stop the sand from moving. You end up with half as much sand or no sand making it from the front side to the back side. It either stops or is pushes back on the beach.”

“You have a developed island, Chincoteague, and then a federally developed island, Wallops, and you have a federally managed island, Assateague,” he said. “Chincoteague Inlet, which is constantly moving, is unique among the Virginia barriers” as it is “stabilized with rock and brick … It’s the only place with an old barrier island, Chincoteague, and … a new barrier island, Assateague, that has grown in front of it. It cut itself off from the open ocean years ago.”

Wallops has grown wider, and Tom’s Cove hook has grown narrower as Chincoteague Inlet has grown wider. This has been the focus of his group for the last year. “Part of the land is trapping an enormous grove of land that should be going to Wallops, Assawoman, Metompkin and Paramore” islands, he said.

VIMS collected sediment cores. “From the thickness of the cores, they can tell how thick fishing point is. They can see how much sand is trapped in that part of Assateague at that time.”

He reviewed a picture with the lower shorelines back to 1859 with the lighthouse that wasn’t built close to the beach. He showed the growth comparing the images with those of modern times and back many years when Ridge Road was a beach. 

Virginia recently provided funds to develop a hydrodynamic model for Chincoteague to predict future movements. Hein’s group will study sand on Chincoteague this summer to determine its age and history.

Building a marsh near Tom’s Cove will be a big challenge due to the risk to shellfish, he said. On Wallops, “they can keep nourishing the beach, but it will still wash away,” he said referring to the money spent to build up the beach near the NASA launchpad.

Projections for sea level rise “are nearly a foot by 2050,” he continued. “The way the currents are, they should fall within the high end of the projections.” 

The beach will steadily roll west even if they build marsh, said Councilman Gene Wayne Taylor. He doesn’t think it will stop migration. 

“It would slow it down,” said Hein. “This is one of those areas that is chaos. It is the most complicated area. It has to be looked at in a strategic and integrated way rather than each individual interaction.”

Paramore Island has some of the highest elevations on the Eastern Shore with 250-year-old dunes, he said. 

Hein offered a review of Hogg Island from the 1865 shoreline. “It has changed more than seven times its own width.”

“It seems like the islands move every week,” the scientist continued. “Most of the barrier islands formed about 6,000 years ago and are constantly moving. They tend to be long and the longest is 100 miles in southern Brazil in South America.”

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