Evaluating the Efficacy of Sand Fences on Dunes Impacted by Hurricanes

Erosion is present in over 90% of the world’s coastlines and poses a threat to infrastructure and natural systems. While the coastal zone is a morphologically dynamic environment, a range of engineering practices have evolved to stabilize it. Because the natural dune system serves as the first line of defense against storm activity and rising sea levels, it is often incorporated into restorative engineering practices. One popular and economical option is the utilization of sand fences. This option is readily available to homeowners and managers, with simple installation requirements. Typically measured for their ability to induce short-term dune growth, scant research has considered storm impact on sand fence installations, their persistence, and the resulting change to dune morphology. This study evaluates the geomorphic response from sand fences resulting from the impact of high energy events, specifically Hurricanes Florence and Michael, which impacted South Carolina in 2018. A combination of cost-effective field methods were applied to calculate dune volume at two sites along a mechanical dune. Measurements compared a site with eleven sand fences and an unmodified control site. Dune volume decreased after Hurricane Florence for both sites but accreted after Hurricane Michael for the fenced site. There was differential morphologic change post-storm between the control and fenced sites, with an overall smaller volumetric loss for the fenced site. Results from this study support the resilience of sand fences under high wind conditions as an effective strategy to aid in dune recovery and growth, suggesting that they can be emplaced prior to the storm season rather than reserved as a post-storm recovery technique. Field observations further suggest the addition of vegetation planted with sand fence installations for optimal dune growth