The dual threats of rising sea level and increased storminess on coastal communities are growing. However, the knowledge gap in the effectiveness of restored coastal dunes, as compared to natural ones, remains – potentially contributing to ineffective coastal management decisions. Incentives specific to the coastal environment, such as sand fencing or nourishment, should be implemented by decision makers to promote the resilience and effectiveness of coastal barriers to the most damaging impacts of climate change. Knowing what approaches work best for coastal protection is key. This study aims to identify the sedimentologic differences of natural and artificial (built) dunes at the Outer Banks, North Carolina, to better understand their relative erodibility. We hypothesize that natural dunes to have a more complex sedimentologic make-up, allowing for the establishment of more stable ecosystems. Therefore, these dunes will be more resilient to storm events (i.e., they will experience less erosion by waves). In contrast, we expect artificial dunes to provide instant flood protection upon construction but may ultimately serve as a less effective barrier to coastal hazards in part due to internal homogeneity. Using sediment core samples and ground-penetrating radar imagery, we observed significant differences in sedimentologic characteristics between natural and artificial dunes, which may explain, in part, the differences in dune response to storm impact their unique protective capacities. Furthermore, we found clear evidence for a rapidly emerging semi-artificial dune forming in front of a built dune from sand delivered through beach nourishment and reworking of that eroded from the artificial dune. This implies that the erosion of constructed dunes provides sediments that could be utilized by natural processes (e.g., wind, waves) to build a natural dune. Results like these will guide coastal engineers in developing suitable solutions to protect coastal communities by applying either a short-or long-term buffer. Essentially, these results guide future efforts towards mitigating the risks of global sea-level rise.
Christopher J. Hein
Strik, Melanie, "The Importance of the Sedimentology of Dunes in the Protection from Sea Level Rise" (2021). Geology Senior Theses. William & Mary. Paper 11.
Available for download on Saturday, May 13, 2023