Assessing Natural and Mechanical Dune Performance in a Post-Hurricane Environment

• Main Authors: Jean T. Ellis, Mayra A. Román-Rivera
• Format: Article
• Language: English
• Published: MDPI AG 2019-05-01
• Series: Journal of Marine Science and Engineering
• Subjects: coastal stabilization; dune recovery; hurricane impact; aeolian geomorphology; beach scraping
• Online Access: https://www.mdpi.com/2077-1312/7/5/126

The purpose of this study is to document the geomorphic evolution of a mechanical dune over approximately one year following its installation and compare it to the recovery of a natural dune following the impact of Hurricane Matthew (2016). During the study period, the dunes’ integrity was tested by wave and wind events, including king tides, and a second hurricane (Irma, 2017), at the end of the study period. Prior to the impact of the second hurricane, the volumetric increase of the mechanical and natural dune was 32% and 75%, respectively, suggesting that scraping alone is not the optimal protection method. If scraping is employed, we advocate that the dune should be augmented by planting. Ideally, the storm-impacted dune should naturally recover. Post-storm vegetation regrowth was lower around the mechanical dune, which encouraged aeolian transport and dune deflation. Hurricane Irma, an extreme forcing event, substantially impacted the dunes. The natural dune was scarped and the mechanical dune was overtopped; the system was essentially left homogeneous following the hurricane. The results from this study question the current practice of sand scraping along the South Carolina coast, which occurs post-storm, emplacement along the former primary dune line, and does not include the planting of vegetation.