Date of Award
12-2024
Document Type
Open Access Thesis
Degree Name
Master of Science (MS)
Department
Environmental Sciences
First Advisor
Mark Borrelli
Second Advisor
Paul Kirshen
Third Advisor
Kirk Bosma
Abstract
Beach profiles are a simple and affordable approach to monitoring changes in beach morphology. However, traditional methods offer limited resolution and dimension. Recent advancements in technologies, particularly structure-from-motion (SfM) and grain size detection models (GSDMs), can be integrated into conventional beach profiling techniques, enabling more detailed spatial and temporal analysis of slope and grain sizes. This research introduces a new technique for coastal monitoring, termed “3D Beach Profiles,” which integrates SfM technology to create high-resolution three-dimensional digital surface models (DSMs) and orthomosaics of beach surfaces. These digital surfaces enable the extraction of beach slopes with orders of magnitude more data than standard beach profiles and the estimation of grain size distributions using GSDMs. The proposed technique is simple and affordable compared to other high-resolution monitoring methods. To evaluate its feasibility and effectiveness, three mixed sand and gravel beaches along the Massachusetts coastline were surveyed seasonally over one year using the 3D Beach Profile method. The findings demonstrate that the technique effectively captures slope changes and estimates grain size distributions. The DSMs produced had an average resolution of 1.2 mm/pixel and an average elevation uncertainty RMSE value of 4.5 cm, comparable to RTK-GPS devices. Extracted 3D Beach Profiles consisted of thousands of points spaced millimeters apart vs tens of points spaced meters apart from two-dimensional beach profiles, capturing slope changes missed by standard beach profiles. Grain size estimates for sediment samples for D10, D50, D90, and mean grain size generated by the segmenteverygrain model had RMSE values under 15 mm compared to measurements by the Camsizer. On average, 80 grains were segmented per quadrat with sizes ranging from 5.50 to 112.08 mm. The 3D Beach Profiles method was particularly successful at Trunk River Beach, capturing storm-driven morphological changes and grain size variations related to slope changes. The surveys provided valuable insights into seasonal rates of change and raised questions about the drivers of these changes. The versatility of the 3D Beach Profiles technique presents opportunities for other coastal monitoring applications. The high-resolution data products generated by this method can better inform beach management decisions and deepen our understanding of coastal processes.
Recommended Citation
Roberts, Kalinda Ellen, "Evaluation of 3D Beach Profiles: A New Method for Monitoring Changes in Beach Morphology and Grain Size" (2024). Graduate Masters Theses. 868.
https://scholarworks.umb.edu/masters_theses/868
Comments
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