scholarly journals Enhanced surf zone and wave runup observations with hovering drone-mounted LiDAR

2021 ◽  
Author(s):  
Julia W. Fiedler ◽  
Lauren Kim ◽  
Robert L. Grenzeback ◽  
Adam P. Young ◽  
Mark A. Merrifield
Keyword(s):  
Surf Zone ◽  
Laser Scanner ◽  
Pressure Sensors ◽  
Phase Speed ◽  
Wave Transformation ◽  
Wave Crest ◽  
Wave Runup ◽  
Terrestrial Lidar ◽  
Nearshore Processes ◽  
Aircraft System

AbstractWe demonstrate that a hovering, drone-mounted laser scanner (LiDAR) paired with a survey-grade satellite and inertial positioning system measures the wave transformation across the surf zone and the resulting runup with accuracy almost equal to a stationary truck-mounted terrestrial LiDAR. The drone, a multi-rotor small uncrewed aircraft system (sUAS), provides unobstructed measurements by hovering above the surf zone at 20 m elevation while scanning surfaces along a 150 m-wide cross-shore transect. The drone enables rapid data collection in remote locations where terrestrial scanning may not be possible. Allowing for battery changes, about 17 minutes of scanning data can be acquired every 25 minutes for several hours. Observations were collected with a wide (Hs = 2.2 m) and narrow (Hs = 0.8 m) surf zone, and are validated with traditional land-based survey techniques and an array of buried pressure sensors. Thorough post-processing yields a stable ( = 1.7 cm) back beach topography estimate comparable to the terrestrial LiDAR ( = 0.8 cm). Statistical wave properties and runup values are calculated, as well as bathymetry inversions using a relatively simple nonlinear correction to wave crest phase speed in the surf zone, illustrating the utility of drone-based LiDAR observations for nearshore processes.

The coastal refraction-diffraction wave propagation model

1995 ◽  
Vol 17 (4) ◽  
pp. 6-12
Author(s):  
Nguyen Tien Dat ◽  
Dinh Van Manh ◽  
Nguyen Minh Son
Keyword(s):  
Wave Propagation ◽  
Field Data ◽  
Surf Zone ◽  
Propagation Model ◽  
Wave Transformation ◽  
Diffraction Effect ◽  
Linear Wave ◽  
Diffraction Wave ◽  
Linear Wave Propagation ◽  
Wave Propagation Model

A mathematical model on linear wave propagation toward shore is chosen and corresponding software is built. The wave transformation outside and inside the surf zone is considered including the diffraction effect. The model is tested by laboratory and field data and gave reasonables results.

Field Observations of Irregular Wave Transformation in the Surf Zone

2001 ◽  
Author(s):  
Nadia Sénéchal ◽  
Philippe Bonneton ◽  
Hélène Dupuis
Keyword(s):  
Surf Zone ◽  
Wave Transformation ◽  
Field Observations ◽  
Irregular Wave

scholarly journals Extended Elliptic Mild Slope Equation Incorporating the Nonlinear Shoaling Effect

2016 ◽  
Vol 23 (s1) ◽  
pp. 44-51 ◽  
Author(s):  
Qian-lu Xiao ◽  
Chun-hui Li ◽  
Xiao-yan Fu ◽  
Mei-ju Wang
Keyword(s):  
Dispersion Relation ◽  
Nonlinear Wave ◽  
Surf Zone ◽  
Wave Dispersion ◽  
Structure Design ◽  
Coastal Engineering ◽  
Wave Transformation ◽  
Flume Experiments ◽  
Mild Slope Equation ◽  
Wave Shoaling

Abstract The transformation during wave propagation is significantly important for the calculations of hydraulic and coastal engineering, as well as the sediment transport. The exact wave height deformation calculation on the coasts is essential to near-shore hydrodynamics research and the structure design of coastal engineering. According to the wave shoaling results gained from the elliptical cosine wave theory, the nonlinear wave dispersion relation is adopted to develop the expression of the corresponding nonlinear wave shoaling coefficient. Based on the extended elliptic mild slope equation, an efficient wave numerical model is presented in this paper for predicting wave deformation across the complex topography and the surf zone, incorporating the nonlinear wave dispersion relation, the nonlinear wave shoaling coefficient and other energy dissipation factors. Especially, the phenomenon of wave recovery and second breaking could be shown by the present model. The classical Berkhoff single elliptic topography wave tests, the sinusoidal varying topography experiment, and complex composite slopes wave flume experiments are applied to verify the accuracy of the calculation of wave heights. Compared with experimental data, good agreements are found upon single elliptical topography and one-dimensional beach profiles, including uniform slope and step-type profiles. The results indicate that the newly-developed nonlinear wave shoaling coefficient improves the calculated accuracy of wave transformation in the surf zone efficiently, and the wave breaking is the key factor affecting the wave characteristics and need to be considered in the nearshore wave simulations.

scholarly journals A Normalization scheme for Terrestrial LiDAR Intensity Data by Range and Incidence Angle

2018 ◽  
Author(s):  
Sandeep Sasidharan
Keyword(s):  
Incidence Angle ◽  
Autonomous Vehicle ◽  
Laser Scanner ◽  
Spectral Information ◽  
Intensity Data ◽  
Automatic Registration ◽  
Terrestrial Lidar ◽  
Intensity Information ◽  
Laser Scanners ◽  
Normalization Scheme

Automatic registration, classification and segmentation of Terrestrial Laser Scanner (TLS) data are of great interest in Geoinformatics & Autonomous vehicle research. Along with dense and accurate 3D geometric data, laser scanners also collect return intensity information. Inclusion of this spectral information has potential to improve the working of the above mentioned processes. However, these intensity values need to be normalized, prior to their use, as they are subject to a large number of errors. This paper presents a technique to carry out normalization of intensity values using the range and incidence angle corrections. The developed approach has been tested on a large number of data and results are found satisfactory.

scholarly journals Estimation of Irregular Wave Runup on Intermediate and Reflective Beaches Using a Phase-Resolving Numerical Model

2020 ◽  
Vol 8 (12) ◽  
pp. 993
Author(s):  
Jonas Pinault ◽  
Denis Morichon ◽  
Volker Roeber
Keyword(s):  
Time Series ◽  
Best Practices ◽  
Numerical Models ◽  
Laboratory Data ◽  
Irregular Waves ◽  
Wave Transformation ◽  
Model Parameters ◽  
Wave Runup ◽  
Data Set ◽  
Promising Alternative

Accurate wave runup estimations are of great interest for coastal risk assessment and engineering design. Phase-resolving depth-integrated numerical models offer a promising alternative to commonly used empirical formulae at relatively low computational cost. Several operational models are currently freely available and have been extensively used in recent years for the computation of nearshore wave transformations and runup. However, recommendations for best practices on how to correctly utilize these models in computations of runup processes are still sparse. In this work, the Boussinesq-type model BOSZ is applied to calculate runup from irregular waves on intermediate and reflective beaches. The results are compared to an extensive laboratory data set of LiDAR measurements from wave transformation and shoreline elevation oscillations. The physical processes within the surf and swash zones such as the transfer from gravity to infragravity energy and dissipation are accurately accounted for. In addition, time series of the shoreline oscillations are well captured by the model. Comparisons of statistical values such as R2% show relative errors of less than 6%. The sensitivity of the results to various model parameters is investigated to allow for recommendations of best practices for modeling runup with phase-resolving depth-integrated models. While the breaking index is not found to be a key parameter for the examined cases, the grid size and the threshold depth, at which the runup is computed, are found to have significant influence on the results. The use of a time series, which includes both amplitude and phase information, is required for an accurate modeling of swash processes, as shown by computations with different sets of random waves, displaying a high variability and decreasing the agreement between the experiment and the model results substantially. The infragravity swash SIG is found to be sensitive to the initial phase distribution, likely because it is related to the short wave envelope.

scholarly journals Studi Hindcasting Dalam Menentukan Karakteristik Gelombang dan Klasifikasi Zona Surf Di Pantai Uluwatu, Bali

2018 ◽  
Vol 5 (1) ◽  
pp. 119
Author(s):  
Karina Santoso ◽  
I Dewa Nyoman Nurweda Putra ◽  
I Gusti Bagus Sila Dharma
Keyword(s):  
Wave Height ◽  
Calculation Result ◽  
Significant Wave Height ◽  
Surf Zone ◽  
Wind Data ◽  
Wave Transformation ◽  
Breaking Wave ◽  
Significant Wave ◽  
The World

Bali is one of the islands where there are many surf zones with various characteristics. In addition, Bali is also a heaven with a classy wave for the surfers of the world. One of the most challenging places to surf in Bali is Uluwatu Beach. Uluwatu Beach is ranked the 3rd best surf spot in the world version of CNN Travel in 2012. Wind causes sea waves, therefore wind data can be used to estimate the height and direction of the waves. Wave Hindcasting with Sverdrup, Munk and Bretschneider (SMB) method is calculated based on wind data for 10 years (2001 - 2010) from BMKG Ngurah Rai Station - Denpasar to obtain a significant wave height and period. In this research, it is necessary to approach through Hindcasting procedure, wave transformation analysis and surfing Terminology in determining the type of breaking wave and classification of surf zone in Uluwatu Beach area. Wave calculation result in Uluwatu Beach dominated by wave that coming from west side with significant wave height (Hs) of 0.98 m and significant wave period (Ts) of 5.21 s. The wave height due to the influence of wave refraction and shoaling is 0.976 m. The breaking wave height obtained from the calculation is 1.04 m at a depth of 0.849 m. From the result in this research, it can be concluded that the breaking wave type that occurred at Uluwatu Beach is plunging type according to the calculation result from its Irribaren number (0.4 <Ni <2.3). The classification of the surf zone at Uluwatu Beach based on its breakup type of wave is thought to be a good zone for surfers on intermediate level.

scholarly journals Morphodynamics Assessment by Means of Mesoforms and Video-Monitoring in a Dissipative Beach

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 448 ◽  
Author(s):  
Juan Montes ◽  
Gonzalo Simarro ◽  
Javier Benavente ◽  
Theocharis Plomaritis ◽  
Laura del Río
Keyword(s):  
Surf Zone ◽  
Video Monitoring ◽  
Spatiotemporal Variability ◽  
Nearshore Processes ◽  
Time Period ◽  
Rocky Outcrop ◽  
Hydrodynamic Data ◽  
Wavelet Analyses ◽  
Macroscopic Analysis

In this study a video-monitoring system was used to analyze the presence of mesoforms during a time period of five years in the urban beach of La Victoria, Cádiz, Spain. This technique allowed the generation of plan views using an improved version of ULISES software. The presence and spatiotemporal variability of the most common mesoforms, such as bars and cusps, was identified in all the plan views. Furthermore, the morphodynamic state of the beach was investigated in combination with local hydrodynamic data. The cusp systems were also studied by means of wavelet analyses and different theories on cusps formation were tested. The presence of the investigated features was related to the wave energy and its seasonal variations. The behavior of the mesoforms demonstrated the important role of a subtidal rocky outcrop in the nearshore processes. The results also show that bars and cusps as indicators of the nearshore processes are a useful tool for the macroscopic analysis of surf zone dynamics in dissipative beaches.

A Study on Wave Transformation Inside Surf Zone

1966 ◽  
Vol 9 (1) ◽  
pp. 69-81 ◽  
Author(s):  
Kiyoshi Horikawa ◽  
Chin-Tong Kuo
Keyword(s):  
Surf Zone ◽  
Wave Transformation

On the interaction of surface and internal waves

1972 ◽  
Vol 52 (1) ◽  
pp. 179-191 ◽  
Author(s):  
A. E. Gargettt ◽  
B. A. Hughes
Keyword(s):  
Surface Wave ◽  
Internal Wave ◽  
Surface Waves ◽  
Internal Waves ◽  
Wind Waves ◽  
Phase Speed ◽  
Surface Current ◽  
Propagation Direction ◽  
Wave Crest ◽  
Critical Position

The steady-state interaction between surface waves and long internal waves is investigated theoretically using the radiation stress concepts derived by Longuet-Higgins & Stewart (1964) (or Phillips 1966). It is shown that, over internal wave crests, those surface waves for which cg0cosϕ0 > ci experience a change in direction of propagation towards the line of propagation of the internal waves and their amplitudes are increased. Here cg0 is the surface-wave group speed at U = 0, ϕ0 is the angle between the propagation direction of the surface waves at U = 0 and the propagation direction of the internal waves, and ci is the phase speed of the internal waves. If cg0cos ϕ0 < ci the direction of the surface waves is turned away and their amplitudes are decreased. Over troughs the opposite effects occur.At positions where the local velocity of surface-wave energy transmission measured relative to the internal wave phase velocity is zero, i.e. cg + U − ci = 0, there is a singularity in the energy of the surface waves with resulting infinite amplitudes. It is shown that at these critical positions two wavenumbers which were real and distinct on one side coalesce and become complex on the other. The critical positions are thus shown to be barriers to the propagation of those wave-numbers. It is also shown that there is a critical position representing the coalescence of three wavenumbers. Surface-wave crest configurations are shown for three numerical examples. The frequency and direction of propagation of surface waves that exhibit critical positions somewhere in an internal wave field are shown as a function of the maximum horizontal surface current. This is compared with measurements of wind waves that have been reported elsewhere.

Dispersion and nonlinearity of multi-layer non-hydrostatic free-surface flow

2013 ◽  
Vol 726 ◽  
pp. 226-260 ◽  
Author(s):  
Yefei Bai ◽  
Kwok Fai Cheung
Keyword(s):  
Deep Water ◽  
Surf Zone ◽  
Perturbation Expansion ◽  
Boussinesq Equations ◽  
Surface Flow ◽  
Second Order ◽  
Superior Performance ◽  
Wave Transformation ◽  
Intermediate Water ◽  
Governing Equations

AbstractNon-hydrostatic multi-layer models have become a popular tool in describing wave transformation from deep water to the surf zone, but the numerical approach lacks a theoretical framework to guide implementation and assist interpretation of the results. In this paper, we formulate a non-hydrostatic model in an analytical form for the derivation and examination of dispersive and nonlinear properties. Depth integration of the dimensionless continuity and Euler equations over each layer yields the conventional multi-layer formulation. A variable transformation converts the conventional form into an integrated series form, which provides separate descriptions of flux- and dispersion-dominated processes. Substitution of the non-hydrostatic pressure and vertical velocity in the governing equations by high-order derivatives of the horizontal velocity and surface elevation provides a direct comparison with the Boussinesq equations published in the literature. Implementation of a perturbation expansion extracts the first- and second-order governing equations with respect to the nonlinear parameter. Based on that, we derive analytical solutions of the linear dispersion and the second-order super- and sub-harmonics for up to three layers and optimize the solutions in terms of the layer arrangement. In relation to the Boussinesq equations at comparable orders of expansion, the two- and three-layer models provide slightly higher errors in shallow and intermediate water in terms of dispersion and super-harmonics, but show superior performance in describing sub-harmonics in deep water.

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