Breaking Wave Height Research Articles

REDESIGN SHORE PROTECTION KAWASAN INDUSTRI KENDAL (KIK)

Abrasion incidents on the coastline in the KIK area continue to occur and cause the area boundaries to decline. so that appropriate coastal protection structures are needed. The aim of this research is to carry out re-planning in the Kendal Industrial Area (KIK) in the future area boundary plan. In carrying out this research, daily wind data for the period 2017 - 2023 is needed from a nearby location, namely the Tanjung Emas Maritime Meteorological Station, Semarang. The analysis carried out includes fetch, windrose, wave calculations, building design and force calculations in shore protection construction. From the results of the windrose analysis, the dominant wave direction is northwest. Analysis of waves in the deep sea obtained a height value of 2.45 m and a wave period of 8.32 sec. Based on the calculation results, breaking waves will occur at a depth of 2.02 m. Because the building location is at a depth of 2m, where breaking waves occur, the breaking wave height is used in building planning. The coastal protection building chosen is shore protection construction or a tetrapod sea wall. Peak elevation of 4.76 meters, peak width of 3.55 meters, building base length of 22.45 meters, back slope of 1:1, arm slope of 1:2, the first type of protective layer material uses tetrapods, second and third layer using split stone pairs with 2 size combinations.

Alongshore sediment transport rate –measurement and comparison with empirical formulas and an Artificial Neural Network (ANN) model

The rate from alongshore sediment transport in the surf zone depends on the product of the local wave height and mean alongshore current speed. The aim of this article was to predict the alongshore sediment transport rate using a semi-empirical application of Artificial Neural Network (ANN) on the south coast of the Caspian Sea. This study reports the measurements of the alongshore sediment transport rate performed in the surf zone of the Noor coastal area located in the southern part of the Caspian Sea from September 2011 to June 2012. Further, alongshore sediment transport rates have been estimated by different famous semi-empirical formulas. On the other hand, an artificial neural network model was trained using three predominant parameters of sediment transport formulas including wave-breaking height (Hb), surf zone width (W), and alongshore current velocity (V). ANN models were able to show hidden laws of natural phenomena such as the sediment transport process. The results of ANN and some sediment transport rate formulas concerning alongshore sediment transport rate were compared with corresponding measured values. Sediment transport is still an evolving science because it depends on complex processes. It is worth mentioning that some of these processes have not been measured or fully understood. Therefore, it is necessary for engineers to pay attention to the fact that even the best forecasts available in the field of sediment transport have a wider margin of error than the forecasts expected in other disciplines and fields of science and engineering. The results show that the estimated value of alongshore sediment transport rate by Coastal Engineering Research Center (CERC), Walton and Bruno, Kamphuis formulas

A Sea State Dependent Gas Transfer Velocity for CO2 Unifying Theory, Model, and Field Data

AbstractWave breaking induced bubbles contribute a significant part of air‐sea gas fluxes. Recent modeling of the sea state dependent CO2 flux found that bubbles contribute up to ∼40% of the total CO2 air‐sea fluxes (Reichl & Deike, 2020, https://doi.org/10.1029/2020gl087267). In this study, we implement the sea state dependent bubble gas transfer formulation of Deike and Melville (2018, https://doi.org/10.1029/2018gl078758) into a spectral wave model (WAVEWATCH III) incorporating the spectral modeling of the wave breaking distribution from Romero (2019, https://doi.org/10.1029/2019gl083408). We evaluate the accuracy of the sea state dependent gas transfer parameterization against available measurements of CO2 gas transfer velocity from 9 data sets (11 research cruises, see Yang et al. (2022, https://doi.org/10.3389/fmars.2022.826421)). The sea state dependent parameterization for CO2 gas transfer velocity is consistent with observations, while the traditional wind‐only parameterization used in most global models slightly underestimates the observations of gas transfer velocity. We produce a climatology of the sea state dependent gas transfer velocity using reanalysis wind and wave data spanning 1980–2017. The climatology shows that the enhanced gas transfer velocity occurs frequently in regions with developed sea states (with strong wave breaking and high significant wave height). The present study provides a general sea state dependent parameterization for gas transfer, which can be implemented in global coupled models.

Development of novel parametric wave model for irregular wave height transformation

Wave height transformation is one of the most crucial parameters in studying coastal engineering as well as designing coastal structures. In this study, a wave energy dissipation model for predicting the transformation of root-mean-square wave height is proposed by using a parametric wave approach over enormous measured data. Additionally, 12 existing energy dissipation models are selected in order to verify their reliability in wave height prediction and compared with a novel formula in terms of error indices, standard deviation, capacity prediction, and root-mean-square relative error. Compiled experimental data with 5783 data are collected for examination and development. The results present that the root-mean-square relative error of existing formulas is in a range from 6.4% to 10.9%. The best existing formulas predict wave height pretty well with a root-mean-square relative error of 6.4% and a standard deviation of 11.0%. Regarding the new model, the best novel model which uses breaking wave height formula of Miche (1944) displays a lower value of root-mean-square error (6.1%) and standard deviation (8.8%) in comparison with the best existing formulas. To confirm the superior performance of the proposed model, all existing models and the best developed model are verified and compared with additional data. The accuracy of the proposed formula over verified data is still better than all existing formulas. Therefore, the novel model is strongly recommended for estimating the transformation of root-mean-square wave height.

Near-surface characteristics of velocity profile and momentum transport after wave-breaking in deep water

Wave-breaking plays an important role in the process of mixing in the upper ocean, which can cause wave momentum and energy flux loss, enhance near-surface turbulence, and adjust the distribution of the momentum flux at the air-sea interface. In this paper, wave-breaking was generated using a laboratory method of controllable deep water breaking waves, and flow field characteristics after wave-breaking were measured and analyzed using PIV technology and the ensemble average method. The velocity threshold was proposed for the effective influence of wave-breaking on the flow field, then the EID (Effective-Influenced-Depth) of wave-breaking, which is Dv in the paper, was quantified, and the quantitative relationship between Dv and energy loss induced by breaking was established. Velocity characteristics of the near-surface flow field and transport characteristics of horizontal momentum induced by wave-breaking were analyzed, which can contribute to the parameterization of wave-breaking. The results show that the energy injected by wave-breaking is transported downstream along the direction of wave propagation. The vertical-influenced range of wave-breaking is about 1–2 times the wave-breaking height. The time integral of horizontal momentum flux increases significantly in the depth of about 1 time the wave-breaking height near the surface and decays significantly with depth. Mass transport of the fluid near the surface induced by wave-breaking mainly occurs in the depth where momentum flux increases significantly. After about 29 times the SWWP (spectrally weighted wave period) after breaking, fluid near the surface is no longer under the action of horizontal stress induced by wave-breaking, so no mass transport occurs anymore. For parameterization of wave-breaking in circulation models, the research can provide a reference in time and space scale, as well as experimental data support for the establishment of a new influence mode.

Prediction of breaking wave height by using artificial neural network-based approach

This study applies artificial neural network-based methodology to predict the breaker height (Hb). 1120 data samples from 53 experiments covering a wide range of seabed slopes are used to examine 36 existing models and artificial neural network (ANN) models. The results indicate that the developed models are more reliable than existing models not only in overall cases but also in any slope range (horizontal, gentle, intermediate, and steep slope). Especially for ANN model 1, root-mean-square-relative error reduces 3.2%–5.9% in comparison with the three best existing formulas in general. Additionally, there is more than 90% of calculated data that differ from measured data by less than 20% as using ANN model 1, this result is better than all existing formulas. In case of classification according to surf similarity wave, ANN model 1 is also better at estimating breaking wave height for both spilling and plunging types. The sensitivity analyses for seabed slope, water depth, and deep-water wavelength with various models are also carried out. The effect of slope, breaker depth, deep-water wavelength, and deep-water wave height on Hb is quite similar to existing models. Based on the outstanding results, ANN model 1 is acceptable and highly recommended to apply in estimation of breaker height.

Limitations of the Yang’s breaking wave force formula and its improvement under a wider range of breaker conditions

Abstract Some commonly used empirical formulas (e.g., Soviet CHиПII57-75, Ikeno-Tanaka, Führböter-Sparboom, and Stanczak) for estimating plunging breaker wave slamming pressure on sea dike surface do not take into account the comprehensive influence of the wave steepness, slope angle, and breaker height and depth on the loads, and the Yang formula eliminates the drawback. The Yang formula is derived based on an analysis of the impulse in the breaking wave tongue and the kinetic and potential energy in the wave tongue. But the limited range of the Yang formula is 0.5 ≤ ξ ≤ 3.3 and 0.01 ≤ tan α ≤ 0.44; otherwise, its prediction error will greatly increase. In addition, some parameters in the Yang formula need to be optimized. The aim of this project is to revise the Yang formula for improving its performance and making it suitable for a wider range of hydraulic conditions and bottom slope conditions. A constant term in the Yang formula is replaced by the function obtained by analysis, and the calculation method of breaking wave height in the formula is also changed. The resulting formula is of interest because the comparison of the formula with some measurements is done well.

Empirical estimation of the breaker index using a stereo camera system

To understand the wave-breaking phenomenon that affects coastal structures and sediment transport, various experiments have been conducted using an experimental wave flume equipped with point observation instruments including wave gauges. However, it has been still challenging to precisely measure the wave propagation in the breaking region. In this study, the water surface elevation is observed using stereo cameras, and a modified index for the breaking wave height is proposed. Water surface fields are retrieved spatially and temporally from synchronized stereo images using the wave acquisition stereo system (WASS), and then the breaking wave height, location, and wave front slope angle (WFSA) are analyzed. For the verification of the camera system, a three-dimensional reconstructed map is compared with the wave elevation measured by the wave gauge. The critical WFSA is empirically formulated and used to modify the breaker index. We verify the proposed breaker index formula by applying the index to the spilling breakers with a wide range of relative water depths. The prediction of the breaker index that rapidly decreases under high relative water depth conditions is considerably improved. Using the proposed critical WFSA formula and modified breaker index, the breaking wave heights in coastal areas can be accurately estimated.

Impact Assessment of Breaking Waves Criteria Subjected to Wave Energy Converter

Breaking wave effect on Wave Energy Converter (WEC) represents an important issue of site selection analysis especially fringing reefs area. To learn a more acceptable sense of the influence of this effect, an introspection on the estimate of initial breaker points is proposed in the present study. The paper describes an investigation of the impact assessment of wave-breaking criteria subjected to WEC recently desired as a benchmark by the previous three wave-breaking methods. The numerical simulation is carried out by the Computational Fluid Dynamics (CFD) solver. The solver is based on the Finite Volume Method (FVM) to create the discretization of the governing equations. Large Eddy Simulation (LES) is solved in a global approach together with Volume of Fluid (VoF) for capturing free surface. Reported justifications are compared with the experimental data to validate the accuracy of the numerical approach and then applied to generate wave-breaker point location on a fringing reef in Numerical Wave Tank-based (NWT) of 16 scenarios. The results are discussed with respect to relative wave-breaker locations, relative wave-breaker height range, and wave breaking probability under various wave steepness, water depth, and slope fringing reef. It is given regarding the discrepancy between different methods and recommendations for important guidances are outlined.

EFEK MANGROVE TERHADAP PEREDAMAN ENERGI GELOMBANG

The research was conducted in Malalanda Village and Linsowu Village, North Buton Regency in November 2021 by collecting primary data (interviews and direct measurements in the field) and processing secondary data to determine the role of mangroves in reducing wave energy based on mangrove conditions (density, thickness and diameter of mangrove trunks). ) using the Thaha Method (2001). Wave conditions in the Kulisusu Bay area are predicted using wind data from the Beto Ambari Bau-Bau BMKG Station followed by predictions of the height and depth of the breaking waves. Changes in shoreline at two research stations that have different coastal protection (dykes and mangrove forests) were analyzed using ArcGIS 10.3 software and then expressed changes in shoreline in quantitative units. Based on the results of the analysis, it was found that the maximum wave height in the study area ranged from 2.27 m – 3.9 m with a maximum breaking wave height of 2.50 m and 3.57 m at a depth of 1.07 m – 3.15 m at a distance of 100 m to 200 m. The change in shoreline is greater at station 2, which is 6.48 m, and the condition of the mangrove forest at the research station has a thickness of 65.61 m and a porosity of 0.72 capable of damping waves with values ranging from 26.424% - 99.98%.Keywords: wave, mangrove, wave attenuation

Study of dynamics of coastal sediment cell boundary in Cirebon coastal area based on integrated shoreline Montecarlo model and remote sensing data

The dynamics of the coastal cell boundary in the Cirebon coast have been investigated. The edge of the sediment cell is unique, with a river mouth and very active shoreline movement. A groin-like structure model with the sediment output at the end of the structure is solved analytically using Laplace transforms methods. The morphological changes of these cell sediment boundaries were analyzed using modeling, field measurements, and Landsat satellite data. The study area consists of a single cell with boundaries of fine sediments containing coral fractions. The middle cell is generally a beach with mangroves with fish or a salt pond beach. The observations using Landsat imagery from 1978 to 2021 show changes in the boundary of sediment cells moving forward to the west as far as 1230 m. We use 1985 as the initial cell boundary for our modeling, with a cell boundary length of 1200 m from the shoreline. The first scenario with constant sediment rate input get shoreline changes from 1100 m from the cell boundary. Still, a linear sediment rate results in the coastline moving upward to 1190 m. The third scenario with periodic sediment input with a monsoon period gives a coastline addition of 750 m at the estuary of the cell boundary and erosion (240 m) in an area far from the cell boundary. The Montecarlo simulation generates a breaking wave with a Gaussian random function that produces a breaking wave height with a dominant variation between 0.5 - 1.5 m. The evolution of the coastline with a constant sediment rate resulted in the most developed beach as far as 1000 m with a relatively large chance of reaching 4000. As for the linear rate, producing a coastline with the highest probability of about 1200 m and periodic sediment rates created the most significant for the coastline between 1000–2500 m.

Estimation of Wave-Breaking Index by Learning Nonlinear Relation Using Multilayer Neural Network

Estimating wave-breaking indexes such as wave height and water depth is essential to understanding the location and scale of the breaking wave. Therefore, numerous wave-flume laboratory experiments have been conducted to develop empirical wave-breaking formulas. However, the nonlinearity between the parameters has not been fully incorporated into the empirical equations. Thus, this study proposes a multilayer neural network utilizing the nonlinear activation function and backpropagation to extract nonlinear relationships. Existing laboratory experiment data for the monochromatic regular wave are used to train the proposed network. Specifically, the bottom slope, deep-water wave height and wave period are plugged in as the input values that simultaneously estimate the breaking-wave height and wave-breaking location. Typical empirical equations employ deep-water wave height and length as input variables to predict the breaking-wave height and water depth. A newly proposed model directly utilizes breaking-wave height and water depth without nondimensionalization. Thus, the applicability can be significantly improved. The estimated wave-breaking index is statistically verified using the bias, root-mean-square errors, and Pearson correlation coefficient. The performance of the proposed model is better than existing breaking-wave-index formulas as well as having robust applicability to laboratory experiment conditions, such as wave condition, bottom slope, and experimental scale.

BREAKING WAVES HEIGHT FORECASTING AT THE SHORELINE OF PANCENG SUB-DISTRICT GRESIK DISTRICT

Shoreline is a line where the edge of the land and the sea met. Various amount of shore construction was built around the shoreline. The safety of surrounding community near the shoreline should be considered before the government planning on near shore and shoreline facility. Therefore, breaking waves height become important because of the impact that it brought to the shoreline, such as the destructive energy that breaking waves generates which would wipe anything that existed alongshore.
 Using the data collected from BMKG (Meteorology, Climatology, and Geophysics Council), maximum wind stress at the Panceng Sub-District was 17,2 m/s. Average effective fetch at Panceng Sub-District was 331,68 km with 5 m significant wave height and 11,2 s period. Breaking wave height at Panceng Sub-District is 5,5 m.

KONDISI HIDRODINAMIKA DAN TRANSPOR SEDIMEN DI MUARA SUNGAI PALU

Sedimentation at the mouth of the Palu River is the cause of frequent flooding in Palu City. This study aims to understand the hydrodynamic conditions and longshore sediment transport around the mouth of the Palu River. Hydrodynamic conditions were analyzed by measuring velocity and current direction, salinity, discharge, breaking wave height, breaking wave depth, wave incidence angle, water density, and water depth. While the amount of longshore sediment transport was calculated based on the CERC empirical formula. The results revealed that the distribution of currents at the mouth of the Palu River was dominated by river currents, where the amount of seawater in the mouth of the river was small. This could be seen from the small salinity value, which ranged from 1 ‰ to 5 ‰. The longshore sediment transport around the Palu River estuary is 36.06 m3/day, where this sediment resulted in silting at the Palu River estuary during deposition.

Simple Breaker Index Formula Using Linear Model

Breaking waves generated by wave shoaling in coastal areas have a close relationship with various physical phenomena in coastal regions. Therefore, it is crucial to accurately predict breaker indexes such as breaking wave height and breaking depth when designing coastal structures. Many studies on wave breaking have been carried out, and many experimental data have been documented. Representative studies on wave breaking provide many empirical formulas for the prediction of breaking index, mainly through hydraulic model experiments. However, the existing empirical formulas for breaking index determine the coefficients of the assumed equation through statistical analysis of data under the assumption of a specific equation. This study presents an alternative method to estimate breaker index using representative linear-based supervised machine learning algorithms that show high predictive performance in various research fields related to regression or classification problems. Based on the used machine learning methods, a new simple linear equation for the prediction of breaker index is presented. The newly proposed breaker index formula showed similar predictive performance compared to the existing empirical formula, although it was a simple linear equation.

Experimental study of the effect of wind above irregular waves on the wave-induced load statistics

The design load from waves on offshore structures are often estimated by aid of experimental studies in wave flumes and basins. When going from open sea to laboratorial conditions a number of factors are either added or omitted such as wind above waves. The paddle-generated waves are based on a spectrum taking the indirect effect of wind into account, whereas the direct effect of wind is left out. Previous studies have focused on the direct effect of wind on waves themselves, but no investigations on the load have been made. The question is whether or not airflow separation, vortexes etc. in the wind field alter physical properties such as steepness of waves, the number of breaking waves and hereby the force; especially the in-line force. To investigate the matter, an experimental study of depth-integrated force on a circular cylinder from irregular waves both with and without wind above, was conducted. An objective, when conducting the tests, was to achieve the same significant wave height whether wind was present or not. Exceedance probability curves for wave crest height, depth-integrated force and pressure were obtained. Moreover, a more descriptive assessment of the phenomena was done by studying the average force shape of the hundred largest force events. In addition, there was applied a phase-based harmonic separation method to explore the wind's effect on the harmonic force components of higher order. The front steepness of the waves was clearly increased with the introduction of wind and further increased, when increasing the wind velocity. The introduction of wind consistently increased the number of breaking waves detected with a breaking criterion. The wave-induced load in the tail of the exceedance probability curve was only increased for some of the sea states, when wind was present. This was very dependent on the size of the crest height of the largest breaking waves. The maximum wave-induced pressure in the tail of the exceedance probability curve was on the contrary increased for all sea states, when wind was present, and it kept increasing with increasing wind velocity. For one of the sea states with increased force extrema, the averaged force shape for the hundred largest events of a case with wind revealed a shape with a spiky peak consistent with that generated from breaking waves. This was not present for the case without wind. The separated harmonic contents of the force up to fourth order also showed a tendency towards more energy at harmonic components of higher order for the case with wind.

Factors controlling longshore variations of beach changes induced by Tropical Storm Eta (2020) along Pinellas County beaches, west-central Florida

Tropical Storm Eta impacted the coast of west-central Florida from 11 November to 12 November 2020 and generated high waves over elevated water levels for over 20 hours. A total of 148 beach and nearshore profiles, spaced about 300 m (984 ft) apart, were surveyed one to two weeks before and one to eight days after the storm to examine the beach changes along four barrier islands, including Sand Key, Treasure Island, Long Key, and Mullet Key. The high storm waves superimposed on elevated water level reached the toe of dunes or seawalls and caused dune erosion and overwash at various places. Throughout most of the coast, the dune, dry beach, and nearshore area was eroded and most of the sediment was deposited on the seaward slope of the nearshore bar, resulting in a roughly conserved sand volume above closure depth. The longshore variation of beach-profile volume loss demonstrates an overall southward decreasing trend, mainly due to a southward decreasing nearshore wave height as controlled by offshore bathymetry and shoreline configurations. The Storm Erosion Index (SEI) developed by Miller and Livermont (2008) captured the longshore variation of beach-profile volume loss reasonably well. The longshore variation of breaking wave height is the dominant factor controlling the longshore changes of SEI and beach erosion. Temporal variation of water level also played a significant role, while beach berm elevation was a minor factor. Although wider beaches tended to experience more volume loss from TS Eta due to the availability of sediment, they were effective in protecting the back beach and dune area from erosion. On the other hand, smaller profile-volume loss from narrow beach did not necessarily relate to less dune/ structure damage. The opposite is often true. Accurate evaluation of a storm’s severity in terms of erosion potential would benefit beach management especially under the circumstance of increasing storm activities due to climate change.

Proposing new breaking wave height prediction formulae using gene expression programming

Wave breaking occurs when waves reach a critical level of amplitude, which results in releasing a significant amount of energy. Predicting the wave heights, locations and other characteristics of breaking waves in shallow water is an important area of research. The breaking wave height, which is the most important characteristic, depends on various parameters such as deepwater wavelength, breaking water depth and seabed slope. In this study, new formulae are proposed for predicting the breaking wave height focusing on two types of breaking waves, namely spilling and plunging. The breaking wave types can be classified by using the Iribarren number. A comprehensive set of laboratory and field observations is utilized to develop new formulae based on the Gene Expression Programming (GEP) numerical method. The datapoints representing individual waves whose breaking types have been determined to be different according to different wave breaking classification criteria have been ignored. In comparison with previous formulae, the new formulae proposed based on different breaking types have almost higher accuracy, especially in the plunging case. Therefore, it might be concluded that developing different formulae based on different breaking types, rather than a general one for all types, would lead to more accurate results.

A Comparative Study of Breaking Wave Loads on Cylindrical and Conical Substructures

In the present paper, a comparative study of different cylindrical and conical substructures was performed under breaking wave loading with the open-source Computational Fluid Dynamics (CFD) package OpenFoam capable of the development of a numerical wave tank (NWT) with the use of Reynolds-Averaged Navier–Stokes (RANS) equations, the k-ω Shear Stress Transport (k-ω SST) turbulence model, and the volume of fluid (VOF) method. The validity of the NWT was verified with relevant experimental data. Then, through the application of the present numerical model, the distributions of dynamic pressure and velocity in the x-direction around the circumference of different cylindrical and conical substructures were examined. The results showed that the velocity and dynamic pressure distribution did not change significantly with the increase in the substructure’s diameter near the wave breaking height, although the incident wave conditions were similar. Another important aspect of the study was whether the hydrodynamic loading or the dynamic pressure distribution of a conical substructure would improve or deteriorate under the influence of breaking wave loading compared to a cylindrical one. It was concluded that the primary wave load in a conical substructure increased by 62.57% compared to the numerical results of a cylindrical substructure. In addition, the secondary load’s magnitude in the conical substructure was 3.39 times higher and the primary-to-secondary load ratio was double compared to a cylindrical substructure. These findings demonstrate that the conical substructure’s performance will deteriorate under breaking wave loading compared to a cylindrical one, and it is not recommended to use this type of substructure.

Experimental study and numerical simulation of mean longshore current for mild slope

In this paper, experimental and numerical studies were performed to investigate the characteristics of longshore current under two mild slopes, the results of which may complement the existing studies, which have mainly focused on steep slopes. The experimental results revealed that the average velocity distribution of the longshore current was significantly different under the two different mild slopes. Under the slope of 1:100, the distribution of the averaged longshore current velocity had a downward concave trend at the nearshore side, while under the slope of 1:40 the trend became convex. In addition, the analysis of the numerical results showed that the distribution of the averaged longshore current velocity was affected by the distribution of the wave height within the surf zone and the bottom friction equations, with the influence of the latter being more significant. For the slope of 1:100, the cross-shore variability of alongshore variability can be calculated using the flow-type bottom friction equation, while for the slope of 1:40, the wave-type bottom friction equation can be used instead. Finally, the secondary breaking wave heights for mild slopes and the distribution of wave set-up are also shown in the study.