Nonhydrostatic XBeach Simulation of Wave Transformations in a Fringing Reef Environment: Validation using Field Observations
Date
2024
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Abstract
Modeling wave transformations in nearshore fringing reef environments is an evolving field, especially for engineering applications. This study focuses on wave transformation at Waimānalo Beach, a location that features a shallow fringing reef and sloping seafloor. To study the wave characteristics at the site, the nonhydrostatic version of XBeach (nonhXB), a two-dimension, depth-integrated numerical model is implemented. The offshore boundary wave conditions are provided by the Simulating Waves Nearshore (SWAN) model. The bathymetry for the nonhXB model is prepared using US Army Corps of Engineers (USACE) 1-m resolution LiDAR data, while the bathymetry for the SWAN model is prepared with the NOAA 3-m resolution Continuously Updated Digital Elevation Model. This study adopts an approach by integrating in-situ field observations at Waimānalo Beach, as a method of calibrating the nonhXB model setup for the site. Waves at two nearshore locations were measured using pressure transducers. The results of the field survey reveal infragravity (IG) waves present at both pressure sensor locations. Using spectral input from a nearby offshore wave buoy, the ability of nonhXB to model IG waves was explored. It was found that the simulated results aligned reasonably well with those of the field observations, including IG waves. Finally, the study examined how bottom roughness affects the presence of the IG waves. It was concluded that increasing the bottom roughness decreases the magnitude of the IG waves, as well as the probability of waves breaking at the site.
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Engineering, Bottom roughness, Field survey, Infragravity waves, Nonhydrostatic XBeach
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73 pages
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