M.S. - Ocean and Resources Engineering
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Item Nonhydrostatic XBeach Simulation of Wave Transformations in a Fringing Reef Environment: Validation using Field Observations(2024) White, Charlotte E.; Huang, Zhenhua; Ocean & Resources EngineeringItem THE RELATIONSHIP BETWEEN HYDRODYNAMIC AND MORPHOLOGIC CHANGES AT SUNSET BEACH(2024) Shepherd, Merritt Anne; Stopa, Justin E.; Ocean & Resources EngineeringItem A COMPARATIVE STUDY OF THE TSUNAMIS FROM THE 2021 AND 2023 LOYALTY ISLANDS Mw 7.7 THRUST-FAULT AND NORMAL-FAULT EARTHQUAKES(2024) Robert, William Henry; Cheung, Kwok F.; Ocean & Resources EngineeringItem EXPERIMENTAL INVESTIGATION OF THIN-WALLED CYLINDRICAL CANTILEVER BEAMS UNDERGOING VORTEX-INDUCED VIBRATIONS(2024) Encke, Clara Vanessa; Gedikli, Ersegun Deniz; Ocean & Resources EngineeringItem AN AUTONOMOUS SAMPLER FOR IN-SITU VERTICAL BENTHIC BIOGEOCHEMICAL FLUXES DETECTION(2024) Lamoonkit, Jomphol; Briggs, Ellen; Ocean & Resources EngineeringItem Fluid-Structure Interaction Analysis of an Oscillating Wave Surge Energy Converter using LS-Dyna(2023) Pappas, Kyle; Gedikli, Ersegun D.; Ocean & Resources EngineeringItem Using Nonhydrostatic XBeach to Simulate Wave Transformations in Fringing Reef Environments(University of Hawaii at Manoa, 2023) Chase, Jonathan; Huang, Zhenhua; Ocean & Resources EngineeringNearshore modelling in application for engineering disciplines is still in a state ofdevelopment due to high computational requirements and is difficult to calibrate consistently with field measurements. The scope of this study is to assess the feasibility and limitations of using the Nonhydrostatic version of XBeach (NonhXB, a two-dimensional (2D), phase resolved, depth integrated numerical model) to study the effects of nearshore wave transformations in a fringing reef environment. This study focused on finding the optimal grid size to simulate the breaker zone characteristics in a fringing reef environment by comparing NonhXB results alongside a dataset from a large scale wave flume test. The purpose of this study is to recommend a set of parameters which can be used to quantify the probability of wave breaking and provide a reasonable estimate of the breaker zone width; these parameters include grid resolution, breaker steepness parameter, reform steepness parameter and eddy viscosity. These recommended parameters should be further clarified by field observations in future applications.Item Seasonal Wave Climate Anomalies On The North Shore Indicative Of Erosion Conditions(University of Hawaii at Manoa, 2022) Storey, Andrew; Stopa, Justin E.; Ocean & Resources EngineeringIn recent years, ocean inundation has impacted local infrastructure at Sunset Beach, O`ahu especially when the beach is highly eroded. The objective of this thesis is to explain and identify potential drivers of erosion. Given a lack of sediment observations at Sunset Beach, this study uses a combination of numerical modeling, buoy observations, sediment characteristics, US Army Corps of Engineers Honolulu District’s remote sensing observations, and anecdotal evidence from local community observers to identify the erosion drivers. The seasonal cycle of the wave environment which drives the beach dynamics is dramatic, with large waves in December-March and small waves in May-August. This study relates seasonal wind, wave, and water level anomalies to the recent erosion and negligible erosion years using the various datasets. The wave and wind fields have the largest deviations from the climatological seasonal cycle in the May-August preceding the dramatic erosion which occurs during September-December. The largest and most significant changes are related to the local trade winds variability varying +14% to -23% from the climatological reference. These findings suggest the summer conditions help (or hinder) the beach recovery to endure (or suffer) the average erosive wave conditions experienced in the winter months.Item Detecting Spinner Dolphin (Stenella longirostris) Clicks In Noisy And Low Sampling Rate Hydrophone Recordings(University of Hawaii at Manoa, 2021) Manabe, Kei; Nosal, Eva-Marie; Ocean & Resources EngineeringDevelopment of automated detection algorithms for cetacean vocalizations is important to facilitate marine mammal research. This thesis focuses on click train detection in cases in which sampling rates are too low to capture the full bandwidth of the clicks, and in which impulsive noise confounds current detection methods. We develop an algorithm to detect/classify odontocete click trains based on the regular timing of clicks; the method relies on the slowly- varying nature of Inter-Click Intervals (ICIs) within a click train. The algorithm is refined and evaluated using simulated data. It is motivated and applied to recordings of spinner dolphins collected in Hawaii. Performance is quantified using receiver-operating and precision-recall curves for both simulated and real data. While the method shows promise (including the ability to separate multiple clicking animals) for click trains with stable ICI and in relatively low-noise conditions, the performance on the spinner dolphin dataset is marginal.Item Morphodynamic Changes Due To Calm/moderate Wave Forcing: A Case Study Of Waikīkī Beach(University of Hawaii at Manoa, 2021) Kalksma, Julianne; Stopa, Justin E.; Fletcher, Charles H.; Ocean & Resources EngineeringSea level rise, erosion, and the wave climate influence Waikīkī Beach on the South Shoreof O‘ahu which is a popular beach in metropolitan Honolulu. In response to recent erosion events and on-going beach nourishments, weekly surveys have been collected for the past 3 years, from April 2018 through December 2020, to better understand coastal morphology. Local studies found detailed two-dimensional morphological structures; however, no direct relationships between the offshore driving ocean conditions and Waikīkī Beach have been established. Consequently, the purpose of this study is to relate the offshore wave conditions to sand movement. We use a wave hindcast to quantify relationships between the sand volume and various wave parameters. We find that the two dominant wave parameters driving changes in the sand volume are the wave direction from swells generated in the Southern Ocean (Dps) and Easterly wind wave height (Hse) relative to many other parameters of the wave climate. Both wave sources are active throughout the year and we are unable to discern seasonal beach changes. We find the antecedent wave condition influences the beach state and the previous 50 weeks might affect the present beach state. The spatial relationship between the wave parameters demonstrates clear geophysical oscillations in the sand motion which supports that Dps and Hse are influencing the nearshore dynamics and resultant beach morphology.