• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.1
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• pp.1-6
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• 2016

The effect of reducing wave overtopping by use of the wave return wall was quantitatively analyzed based on physical experiments. The overtopping discharge for the arc seawall and the inclined seawall was measured and compared with the predictive formula that estimates reduction of overtopping by the wave return wall. When the overtopping discharge was relatively large ($q/{\sqrt{gH^3_s}}>10^{-3}$), the agreement in terms of overtopping reduction rate was fairly good between the prediction and the measurement. For the condition of smaller overtopping than the above criterion, however, the discrepancy was large between the predicted and measured result. In this context, it is required to develop a better formula for estimating reduction of wave overtopping by the wave return wall.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.4
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• pp.75-83
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• 2023

Apart from implementing hardware solutions like raising the crest freeboard of coastal structures to efficiently counter wave-overtopping, there is a simultaneous requirement for software-driven disaster mitigation strategies. These tactics involve the swift and accurate dissemination of wave-overtopping information to the inland regions of coastal zones, enabling the regulation of evacuation procedures and movement. In this study, a method was proposed to estimate wave-overtopping by utilizing the temporal variation of wave heights exceeding the structure's crown level, with the aim of developing an on-site wave measurement system for providing wave-overtopping information in the field. Laboratory model experiments were conducted on vertical seawall structures to measure wave-overtopping volumes and wave runup heights under different wave conditions and structural freeboard variations. By assuming that the velocity of water inundation on the top of the structure during wave-overtopping events is equivalent to the long-wave velocity, an overtopping discharge coefficient was introduced. This coefficient was utilized to estimate the rate of wave-overtopping based on the temporal changes in wave runup heights measured at the top of the structure. Upon reasonably calculating the overtopping discharge coefficient, it was verified that the estimation of wave-overtopping could be achieved solely based on the wave runup heights.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.192-199
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• 2024

Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.3
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• pp.175-181
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• 2015

In this study, two dimensional wave overtopping tests for vertical wall were performed and overtopping formulas were suggested for impulsive and non-impulsive wave conditions. The test results from this study were compared with those from EurOtop(2007). The wave overtopping formulas were derived and suggested considering the recent research trends, while the existing method used the diagram. The wave overtopping formulas have the form of exponential and power functions using non-dimensional variables for wave overtopping and freeboard heights for non-impulsive and impulsive condition, respectively. The wave overtopping formula and effective parameters for inclined superstructure were also suggested. It is analyzed that the locations of inclined superstructure do not have the significant effects on wave overtopping, that is, the wave overtopping rate were almost same for each locations.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.2
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• pp.176-183
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• 2008

In this paper, three classical overtopping models: Owen model, Van der Meer & Janssen model and Hedges & Reis model were used to calculate the failure probability of wave overtopping of seawalls. Among of them, the Hedges & Reis model was regarded as a moderate method to analyze the failure probability of wave overtopping of seawalls and the probabilistic assessments of wave overtopping were carried out for a constructing seawall at Busan in Korea by Level II and Level III reliability methods. Considering the cost of construction, an appropriate crest level was proposed for a certain rate of wave overtopping at a lower failure probability.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.372-382
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• 2006

Most of the conventional breakwaters impermeable breakwaters which block seawater exchange between the outside and inside of the harbors. The blocking of seawater exchange may cause pollution of water in harbors. To solve the water pollution problem, various kinds of seawater exchange breakwaters have been proposed. Their types can be classified into the current type which uses tidal current, and the overtopping type which uses the wave energy. The overtopping type breakwaters require a discharge coefficient to calculate the rate of overtopping into the harbor. The present study is to compute the rate of overtopping with introduction of a correct discharge coefficient and to evaluate the effect of the overtopping type breakwater on the water qualify inside a harbor. The rate of overtopping was computed by using Forchheimer formula with time dependent mild-slope equation for various wave conditions. The formula has been generally used to calculate the overflow discharge in steady state river flows. The discharge coefficient, which is the key parameter of the calculation, was determined by a series of hydraulic model tests. The present scheme was applied to the seawater exchange section of the western breakwater of Jeju New Harbor's and the efficiency of that section was examined. The calculated results showed that the rate of overtopping into the harbor reached about $27.5m^3/s$ in the wave condition (wave height 3.7 m, wave period 8.5s, and wave direction NNW).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.2
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• pp.33-40
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• 2023

Wave overtopping rate is one of the most important design parameters for coastal structures. In this study, the physical model tests for measuring the wave overtopping have been conducted with the foreshore slope in front of the seawall. The bottom seabed for the coastal road area was fabricated at the wave flume for two areas in the East sea areas. The wave overtopping rate was measured for various water depths and wave conditions in each coastal area. In particular, the impulsive wave conditions were compared with the previous research and the similar trends of wave overtopping was observed. It could be known that the effect of foreshore slope was significant and should be concerned for applying theses formula like EurOtop.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.373-376
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• 2006

In general, a method for generating irregular wave by combination of component waves obtained from linear wave theory is widely used. In these method, however, mean water surface elevation is rising from time to time because of nonlinear effect of wave. In this study, for the rising problem of mean water surface elevation and stabilization of calculation from time to time, mass transport velocity for horizontal velocity at wave source position is considered. The rising problem of mean water surface elevation is checked by comparing calculated wave profile from numerical technique proposed in this study with target wave profile at wave source position in numerical wave tank by using CADMAS-SURF code. And, by generating irregular wave, the validity of wave overtopping rate estimated from this numerical analysis is discussed by comparing computed results with measured results in hydraulic model experiments for vertical seawall located on a sloping sea bottom. As a results, the computations are validated against the previously experimental results by hydraulic model test and numerical results of this study and a good agreement is observed. Therefore, numerical technique of this study is a powerful tool for estimating wave overtopping rate over the crest of coastal structure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.3
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• pp.228-234
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• 2012

Two-dimensional hydraulic experiments for wave overtopping under non-breaking wave condition are conducted. The wave overtopping formula for vertical structure is suggested and the results are compared with EurOtop (2007). The relative water depth coefficient (${\gamma}_{kh}$) shows that almost the same coefficient is obtained for certain range (kh > 1.55) regardless of relative water depth, that is, although the relative water depth becomes larger, the relative water depth coefficient is almost same. When the wave steepness becomes larger the wave steepness coefficient decreases. The overtopping formula are expressed by relative freeboard(R) and non-dimensional wave overtopping rate(Q) and this formula has the form of exponential function. In this formula, the effects of wave period on wave overtopping are quantitatively investigated and suggested through the relative water depth coefficient(${\gamma}_{kh}$) and wave steepness coefficient(${\gamma}_s$).

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.649-655
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• 2006

Waves progressing into the coastal area can be amplified, swashed and overtopped by a wave overtopping control structure, and it converts the kinetic energy of the waves to the potential energy with a hydraulic head above the mean sea level by conserving the overflow in a reservoir. Then the potential energy in the form of hydraulic head can be converted to electric power utilizing extremely low-head hydraulic turbine. This study aims to find the most optimal shape of wave overtopping structure which maximizes overtopping volume rate of sea water. Laboratory experiments for the performance evaluation of wave overtopping control structures were carried out in three dimensional wave tank, and the three dimensional structure models with planar wave concentration shapes(B/b) were manufactured into five classes, which were optimized by cross sectional parameters of the structure, ie, length of ramp(l), gradient of inclined ramp($cot{\phi}$) and freeboard height of the wave overtopping structure($h_e$) proposed by Shin and Hong(2005). The wave overtopping discharges were investigated with 20 incident wave conditions and wave directions of $0^{\circ},\;15^{\circ},\;30^{\circ}$.