Shifting Sands

Right now on the Outer Banks, there is a newly-emerged sandbar dubbed Shelly Island that is growing impressively off Cape Point, the jutting corner of the Outer Banks known for its vast wild beach and frenzied currents. Thanks to its spectacular location, the expansive island has become a media sensation, attracting hordes of delighted beachgoers, beach drivers, beachcombers, surfers, kite boarders, kayakers or just curiosity-seekers. 

People are absolutely loving it,” exclaims Dave Hallac, the superintendent of Cape Hatteras National Seashore, which includes Cape Point in Buxton. “It’s a phenomenon.” 

But sand is a fickle thing on the Outer Banks. Any old timers worth their salt could easily recite a list of dramatic appearances and disappearances of sand, sometimes in the same day at the same place. Storms fill pools with sand, strip sand from tree roots, carve away chunks of beach at one spot and bury buildings at another. Sometimes all it takes is a brisk, steady wind for a few days, and the sandy landscape is transformed. A nor’easter can make the prettiest beach into a moonscape overnight.

Our narrow strip of world we call the Outer Banks is really just a very long, slowly moving sandbar. 

shelly island
Cape Hatteras National Seashore superintendent Dave Hallac first saw signs of the emerging Shelly Island last winter. By the summer, the stretch of sand located off Cape Point was gaining notoriety nationwide as being the Outer Banks’ newest island. Photo courtesy CBS

Hallac says he started noticing a shoal last winter poking up just off Cape Point. That wasn’t particularly surprising, he says. But then every time he went back to the cape, the sandbar “kept growing and growing and growing.”

By mid-July, it had morphed into a curved island, about a mile long and 300 yards wide. Even those who’ve been going to the Point for decades, he says, marvel at the unique spectacle.

According to Stan Ulanski, a professor of geology and environmental science at James Madison University, Shelly Island is not an unexpected development, considering where it emerged.

“Cape Point is and has been a dynamic coastal feature, changing over time and in spatial dimensions,” he commented recently in the Island Free Press. “The new island is the result of nearshore processes, such as wave interaction and longshore currents, not the result of offshore features, including the Gulf Stream.”

While Shelly Island is dazzling crowds with its astounding growth, just up the road in Buxton, the beachfront is currently undergoing replenishment of the tons of sand that has washed away in recent decades, leaving just a skinny strip of beach to buffer waves. During major storms, the eroded area routinely suffers major ocean overwash and often, damage to motels and other structures.

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Aerial views of the emergence of Shelly Island. Photo courtesy NASA

Similarly the towns of Duck, Southern Shores, Kitty Hawk, and Kill Devil Hills have collaborated on a beach nourishment project which began in late May and is expected to be completed in October.

For a place built on sand, the Outer Banks seems to be losing where it wants it, while gaining it where it doesn’t. At the same time that sand is being pumped onto our beaches, sand is being pumped out of inlets and boat channels. Hatteras Inlet and Oregon Inlet have been plagued with shoaling, especially since Hurricane Isabel in 2003. Dredging projects have had to be done more frequently and at more places to keep passages clear for ferries and charter fishing vessels.

Even the tallest living sand dune on the East Coast at Jockey’s Ridge State Park won’t stay put. In fact, the estimated 30 million tons of sand in the 426-acre park moves around a lot. Since the park was established in 1975, the once-single 140-foot tall dune has evolved into three shorter dunes that range between 80 feet to 90 feet in height. And with the winter’s predominant northeast winds a bit stronger than the summer’s southwest winds, all that sand is being shoved toward the south as much as six feet a year.

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The estimated 30 million tons of sand that make up Jockey’s Ridge is always on the move, migrating to the south by as much as six feet a year. Photo courtesy Frogsview Blog

Shifting sands from the park is now threatening to encroach on Soundside Road, the public street that runs along the south side of the park. Joy Greenwood, the park’s superintendent, says the park is planning a project in the winter of 2018-2019 to haul away sand that is piling up on southwest corner. A similar effort was done in 2004, when 10,000 dump truck loads of sand were removed from the southwest corner.

Even though Jockey’s Ridge is one block from the ocean, its sand is 90 percent quartz, not the ground-up seashells that comprise the sand on the ocean beach, Greenwood explains. That means that Jockey’s Ridge’s geologic origins – amazingly – come from sand blown ages ago from the North Carolina mountains.

But Jockey’s Ridge is the exception. According to veteran coastal geologists Orrin H. Pilkey, Stan Riggs and six others, authors of The North Carolina Shore and Its Barrier Islands: Restless Ribbons of Sand, on barrier islands such as the Outer Banks, the beach is the source of sand for the entire island.

The beach is a complex formation that seeks equilibrium, they write. So where one part of the system builds with sand, another part of the system takes it away.

“Defined as the zone of active sand movement, and extending from the toe of the dune to an offshore depth of 30 to 40 feet, the beach is always changing,” the authors wrote. “The natural laws that govern the beach control a beautiful, logical environment that builds up when the weather is good and strategically (but only temporarily) retreats when confronted by big storm waves. Beaches do such logical and predictable things that they almost seem to be alive.”

Beach behavior, they say, is influenced by four factors: wave energy; the quality and quantity of sand; its shape and location; and the rate of sea level change. When one factor changes, all the rest adjust to keep the balance.

shifting sands
Hurricane Irene caused a breach at New Inlet in 2011. While a temporary bridge was built, since then sand has filled the inlet back in. Construction of the new 2.4-mile Rodanthe Bridge is slated to begin in 2018 along the stretch that is susceptible to erosion and breaches. Photo Left courtesy outerbanks.org; Photo Right courtesy Heidi Gross

Storms often flatten dunes and beaches, but beaches are naturally resupplied from the adjacent shoreface, inlets, deltas and capes. Sand is also carried parallel to the beach by longshore currents. But human interference in the sand transport cycle – whether from dredging inlets (removing sand supply) or by building dunes, breakwaters and jetties (blocking sand travel) can sometimes starve beaches. And anything that affects the sand resupply can create beach erosion, on both ocean and sound sides.

Beach erosion, however, also can be a result of the beach’s geology, the geologists say. For instance, the very high erosion rate along sections of Kitty Hawk and Rodanthe is mostly because of the underwater nearshore structure, which directs wave energy to strike the beach. Some shoreline in Pea Island, Buxton, Hatteras and Ocracoke with high erosion rates had once been inlets, making them likely to be inlets again. And rising seas and increased storm intensity from climate change, along with the continued use of hard structures such as seawalls and sandbags on developed shorelines, will only worsen the rate of erosion. For that reason, beach nourishment will be a continued necessity in resort beach communities.

In a white paper released in 2008 by members of the North Carolina Coastal Geology Cooperative Research Program, North Carolina’s Coasts in Crisis: A Vision for the Future, scientists put the modern Outer Banks in perspective.

Our barrier island system started taking shape about 3,500 years ago, close to where it is still located. It wasn’t until the 15th century that the Outer Banks took the form it more or less has today. Until the 1930s, sand did what sand naturally does – migrating with currents, blowing around in winds, tossed back and forth by waves. Then in the 1930s, the government built dunes, and that was the beginning of the end to the cycle of sand transport and renewal, of the natural equilibrium.

 Later came bridges, roads, buildings and parking lots. Sand started being a problem – piling on roads, clogging inlets and channels. Or disappearing from shorelines, leaving houses and roads inches from crashing waves. As the researchers point out in the paper, the sand was responding to natural forces, and coastal development got in the way. Whatever the interpretation, in the 21st century, sand is important to quality of life on the Outer Banks.

And to our future – because where the sand is, and is not, means everything on the Outer Banks.

“Barrier islands are built by storms and are dependent upon storm events to maintain their short-term health and long-term evolution,” the paper says. “No guaranteed permanency exists for any ecosystem, landform, or built structure on the coast.”♦

 

Catherine Kozak

Catherine Kozak has worked as a writer and reporter on the Outer Banks since 1995. She lives in Nags Head and enjoys running in the woods with her dog, Rosie.

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