Date of Award
4-30-2025
Document Type
Open Access Dissertation
Department
Geography
First Advisor
Jean T. Ellis
Sixth Committee Member
Doctor of Philosophy (Ph.D.)
Abstract
Historically, coastal dunes have been poorly understood from a societal perspective despite their protective role in attenuating incoming waves to reduce onshore flood risk. As developed coastlines promote strategies to design and maintain managed dune systems, it is necessary to ensure these strategies are optimized for dune health and resilience, particularly given the increasing threat of natural and anthropogenic stressors. This dissertation work aims to identify strategies that influence coastal dune management in South Carolina (SC), USA from an integrated approach, including a current use assessment, a mesoscale field-based study on strategy efficacy, and by incorporating a societal assessment and evaluation. First, a digitized inventory for sand fencing – a common and inexpensive management strategy emplaced for dune building – was created for the coastal zone of SC using Google Earth Pro (GE) imagery, with validation by location assessed using a high-resolution 2020 image. Results identified 8194 fences, an identification error of ≤1%, and an average placement error of 1.8 m. Statistical analysis and the integration of grey literature provided context on the utility of sand fences as a coastal management strategy across the state, suggesting 55.4% were associated with beach nourishment and 87% were installed following state-mandated recommendations.
Next, a field-based experiment was conducted for approximately one year at Debordieu Beach, SC to compare the development and storm response for two managed dune systems: one with sand fences and dune vegetation installed on a nourished dune with a graded stoss slope of ~21% and second “management zone” where the same materials were installed on a flat upper backshore with a gradual stoss slope of ~4%. Field surveys took place every ~6 weeks and included terrestrial LiDAR (TLS) topographic surveys for Digital Elevation Model (DEM) generation, vegetation surveys for Object-Based Image Analysis (OBIA), and sediment samples. Result from this study indicate that the initial rate of accretion was inhibited (0.54 m3/day vs 0.96 m3/day) for the site inclusive of a nourished dune slope during pre-storm conditions. Statistically significant (p< 0.001) accretionary and erosional hotspots indicated site-specific morphologic trends that continued during post-storm conditions in relation to scarp formation, onshore transport potential, and roughness element presence. Data from this study provide additional context on the potential trade-offs between nourished dunes, management zones, and management strategy efficacy when considering the protection of landward infrastructure.
Lastly, the study pivots to assess dune management from a societal lens by distributing an electronic survey instrument to 229 residents within the SC coastal zone to assess literacy to coastal dune hazard impacts (tropical cyclones and high tide flooding) and management strategies. Results from this study support that experiential variables (experience with hazard impact; prior loss and frequency of beach visits per year) were statistically significant (p< 0.05) in predicting respondent cumulative literacy scores as developed through the survey instrument. Further, when evaluating respondent familiarity, propensity to support, and ranking for success by coastal management strategies, results supported that each strategy type should be characterized individually, with experiential and sociodemographic variables being statistically significant (p< 0.05) by management strategy type.
Holistically, the results from this dissertation support that coastal dune management in SC (and additional coastal geographies) should be assessed at the local scale, with expectations for results to vary by location, given community experiences, motivations, policies, and preferences. The influence of hazard impact as a variable for increasing dune management literacy, proactive and reactive dune management strategy implementation, and overall dune resilience is worthy of further investigation. In this aspect, this research has introduced new theoretical and methodological contributions to the field of geography and provides impetus for ongoing investigation and motivation for community-based coastal management and implementation.
Rights
© 2025, Michelle Harris
Recommended Citation
Harris, M.(2025). Integrated Coastal Science and Dune Management: A South Carolina Perspective. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8077