Numerical modeling of the effect of variable wind direction on migration of sand dunes at Jockey’s Ridge, North Carolina

Jockey’s Ridge State Park in the Outer Banks of North Carolina hosts the largest sand dunes in the eastern US. These dunes are migrating southward, causing massive quantities of sand to threaten nearby infrastructure including houses and roads. Numerical models could help improve forecasts for dune migration and have been previously applied to Jockey’s Ridge assuming a unidirectional wind field. However, a major knowledge gap remains for predicting dune migration under seasonal winds that vary in magnitude and direction. To address this gap, I rebuilt a reduced-complexity model for sand dune development (Werner, 1995; Pelletier et al., 2009) and extended the model to account for winds in any direction. I found that in model scenarios seeded with random initial topography, bimodal wind directions favor (1) the formation of dunes as connected ridges instead of isolated, crescentic barchans dunes; and (2) slower dune migration. I then ran a hindcast for Jockey’s Ridge from 1999 to 2008 to compare model predictions with and without variable wind directions to observed migration patterns. These comparisons show that the model with variable wind directions predicts more westerly migration and taller dunes compared to observed topographic evolution and predictions from existing models. This work establishes a foundation for future efforts to relate dune migration to wind fields at Jockey’s Ridge and provides actionable predictions for managing dune migration in the coming decades.