Breaking Wave Imaging Using Lidar and Sonar

Bryan, Oscar; Bayle, Paul M.; Blenkinsopp, Christopher; Hunter, Alan J.

doi:10.1109/joe.2019.2900967

Cited by 3 publications

(3 citation statements)

References 45 publications

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“…The presence of air bubbles associated with wave breaking processes prevents sound waves to reach the surface, hence making this method inappropriate for surf zone applications (Birch et al, 2004). In this case, bottom-mounted acoustic sensors would typically measure the lower bound of the surface roller structure (see illustration in Figure 1) or air pockets, which can be used in order to characterize breaking wave-induced air plumes in large scale experiments (Bryan et al, 2019).…”

Section: Direct Measurements Of Surf Zone Wavesmentioning

confidence: 99%

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

et al. 2020

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In the surf zone, non‐hydrostatic processes are either neglected or estimated using linear wave theory. The recent development of technologies capable of directly measuring the free surface elevation, such as 2‐D lidar scanners, allow for a thorough assessment of the validity of such hypotheses. In this study, we use subsurface pressure and lidar data to study the non‐linear and non‐hydrostatic character of surf zone waves. Non‐hydrostatic effects are found important everywhere in the surf zone (from the outer to the inner surf zones). Surface elevation variance, skewness, and asymmetry estimated from the hydrostatic reconstruction are found to significantly underestimate the values obtained from the lidar data. At the wave‐by‐wave scale, this is explained by the underestimation of the wave crest maximal elevations, even in the inner surf zone, where the wave profile around the broken wave face is smoothed. The classic transfer function based on linear wave theory brings only marginal improvements in this regard, compared to the hydrostatic reconstruction. A recently developed non‐linear weakly dispersive reconstruction is found to consistently outperform the hydrostatic or classic transfer function reconstructions over the entire surf zone, with relative errors on the surface elevation variance and skewness around 5% on average. In both the outer and inner surf zones, this method correctly reproduces the steep front of breaking and broken waves and their individual wave height to within 10%. The performance of this irrotational method supports the hypothesis that the flow under broken waves is dominated by irrotational motions.

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Section: Direct Measurements Of Surf Zone Wavesmentioning

confidence: 99%

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

et al. 2020

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“…A Reson SeaBat 7125 multibeam echo-sounder was deployed to obtain pilot measurements of the bubble clouds generated by wave breaking 11 and non-intrusive, regular measurements of the submerged beach profile. The echo-sounder was mounted on a vertical arm fixed to the overhead trolley of the mechanical profiler.…”

Section: Methodsmentioning

confidence: 99%

“…The availability to researchers of large-scale measurements of nearshore hydro and morphodynamics at the spatio-temporal resolution achieved during DynaRev is very limited. Potential uses for the datasets obtained during the DynaRev test program are wide-ranging and include: the assessment of dynamic cobble berm revetment performance 6 , the investigation of nearshore processes such as the formation and dynamics of nearshore sandbars 7 , the response of sandy coasts to a rising sea level 8 , morphology change in the swash zone 9 , wave-by-wave sediment transport rates 10 , air entrainment in breaking waves 11 and the development of numerical models 12 .…”

Section: Background and Summarymentioning

confidence: 99%

High-resolution, large-scale laboratory measurements of a sandy beach and dynamic cobble berm revetment

et al. 2021

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High quality laboratory measurements of nearshore waves and morphology change at, or near prototype-scale are essential to support new understanding of coastal processes and enable the development and validation of predictive models. The DynaRev experiment was completed at the GWK large wave flume over 8 weeks during 2017 to investigate the response of a sandy beach to water level rise and varying wave conditions with and without a dynamic cobble berm revetment, as well as the resilience of the revetment itself. A large array of instrumentation was used throughout the experiment to capture: (1) wave transformation from intermediate water depths to the runup limit at high spatio-temporal resolution, (2) beach profile change including wave-by-wave changes in the swash zone, (3) detailed hydro and morphodynamic measurements around a developing and a translating sandbar.

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3D Ocean Water Wave Surface Analysis on Airborne LiDAR Bathymetric Point Clouds

et al. 2021

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Water wave monitoring is a vital issue for coastal research and plays a key role in geomorphological changes, erosion and sediment transportation, coastal hazards, risk assessment, and decision making. However, despite missing data and the difficulty of capturing the data of nearshore fieldwork, the analysis of water wave surface parameters is still able to be discussed. In this paper, we propose a novel approach for accurate detection and analysis of water wave surface from Airborne LiDAR Bathymetry (ALB) large-scale point clouds data. In our proposed method we combined the modified Density-Based Spatial Clustering of Applications with Noise (DBSCAN) clustering method with a connectivity constraint and a multi-level analysis of ocean water surface. We adapted for most types of wave shape anatomies in shallow waters, nearshore, and onshore of the coastal zone. We used a wavelet analysis filter to detect the water wave surface. Then, through the Fourier Transformation Approach, we estimated the parameters of wave height, wavelength, and wave orientation. The comparison between the LiDAR measure estimation technique and available buoy data was then presented. We quantified the performance of the algorithm by measuring the precision and recall for the waves identification without evaluating the degree of over-segmentation. The proposed method achieves 87% accuracy of wave identification in the shallow water of coastal zones.

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Breaking Wave Imaging Using Lidar and Sonar

Cited by 3 publications

References 45 publications

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

High-resolution, large-scale laboratory measurements of a sandy beach and dynamic cobble berm revetment

3D Ocean Water Wave Surface Analysis on Airborne LiDAR Bathymetric Point Clouds

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