Shifting Sands Part of Jockey's Ridge Evolution
Jockey's Ridge State Park boasts the tallest natural sand dunes on the East Coast, but the claim to fame doesn't loom as large as it once did. The dunes now measure 21 meters above sea level, down more than a third from when the state park was formed in 1974 and by half from the 42-meter height some 60 years ago. "The dunes are essentially flattening as winds move the sand to the south," says Dr. Helena Mitasova, an associate professor in the Department of Marine, Earth and Atmospheric Sciences.
"The large dune is a relatively recent and short-term phenomenon."
An expert in coastal topography and landscape evolution, Mitasova has studied Jockey's Ridge for several years. By reviewing hand-drawn and aerial maps dating to the 19th century and using aerial laser scanning to produce high-resolution, 3-D digital models of the area, her research team has determined that the park is undergoing a natural evolution. Geologists who took core samples of the area previously determined that it had cycled between sand dunes and a maritime forest twice in the past millennium. "The large dune is a relatively recent and short-term phenomenon," Mitasova says. The dunes doubled in size between World War I and the early 1950s before shrinking back in recent decades. One of Mitasova's graduate students, Katie Weaver, is studying the vegetation around the dunes to determine if that contributed to their changing stature. Mitasova and Dr. Margery Overton, a professor in the Department of Civil, Construction and Environmental Engineering, have used aerial laser scanning to map the beach and dunes along much of the Outer Banks. They developed techniques to determine the stable "core" of the areas and the surrounding "envelope" of shifting sands. The method allows them to track the extreme changes in the volume of beach and sand, which helps with coastal management strategies. By applying the analysis to Jockey's Ridge, Mitasova's team has determined that the dunes are shifting to the south by 3 to 6 meters a year. "The main dune is now lower than the west dune," she says.
The state scooped out part of the southern edge of Jockey's Ridge in 2003 because it was poised to bury nearby homes, and crews deposited the sand to the north of the main dune. Mitasova says that strategy seems to be replenishing the dunes without interfering with the area's evolutionary cycle. "It's a question of, do we preserve the feature or the process," she says. "Our research is helping to design strategies to preserve this unique landform as a living, ever-changing feature."
Agencies providing funding for research cited in this story include: