scholarly journals Vulnerability Analysis of Episodic Beach Erosion by Applying Storm Wave Scenarios to a Shoreline Response Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Tae-Kon Kim ◽  
Changbin Lim ◽  
Jung-Lyul Lee
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Vulnerability Analysis ◽  
Coastal Development ◽  
Beach Erosion ◽  
Mathematical Function ◽  
Observation Data ◽  
Response Model ◽  
Wave Condition ◽  
Storm Wave

Recently, because of the influence of climate change on sea level change, there has been growing concern regarding the erosion of beaches, which play a role in reducing the damage caused by coastal disasters. However, despite these concerns, a comprehensive understanding of the morphodynamic relationship between hazard factors and beach erosion is still lacking. Therefore, in this study, a vulnerability analysis of beach erosion was conducted by applying the shoreline response model (SLRM) of bulk model type, which identifies the physical characteristics of relevant coefficients based on the suspended sediment movement processes. To characterize wave energy incidence, storm wave scenario modeling and extreme wave analysis were conducted using wave data of 40 years on the east coast of Korea provided by the National Oceanic and Atmospheric Administration. A dimensionless mathematical function representing the storm wave scenario was proposed as a function of the peak wave height. In addition, to examine whether the beach vulnerability curve (BVC) obtained from the SLRM is valid, it was compared with the long-term shoreline observation data conducted at Maengbang Beach. For the past 9 years, sand sampling and shoreline observations were performed at Maengbang Beach about 5 times a year. However, since observations were performed in time intervals of several months, the direct comparison with model results was impossible, so a comparative analysis through statistical analysis of shoreline variability was performed. The variability of the shoreline for each reference point followed a normal distribution with a standard deviation of approximately 7.1 m. As a result of comparing the BVC results obtained from these statistical characteristics with those obtained from the model, significant similarity was shown in the high wave condition. Finally, the model was performed on two factors (mean wave height and peak wave height) which appear in SWSF and three factors (wave energy at breaking point, beach response factor and beach recovery factor) which appear in SLRM, and by analyzing the results, an approximate formula for the BVC is derived. This novel BVC approximation equation provides an intuitive understanding of the factors that affect beach vulnerability as well as their importance, and estimates the beach buffer section required to prevent coastal facilities from being damaged by erosion during a specific period. The results of this study can help limit reckless coastal development and mitigate erosion damage.

scholarly journals Characteristics of Hydro-Oceanography in the Coastal Waters of Kura-Kura Beach, Bengkayang Regency

2021 ◽  
Vol 6 (1) ◽  
pp. 45
Author(s):  
Muhardi Muhardi ◽  
Risko Risko ◽  
Heni Susiati
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Current Velocity ◽  
Flow Analysis ◽  
Ocean Waves ◽  
Observation Data ◽  
Yield Model ◽  
Intermediate Period ◽  
Simulation Results ◽  
First Intermediate Period

The waters of Kura-Kura Beach have quite a lot of human activities, one of which is tourism. The study aims to observe Hydro-Oceanographic parameters such as tidal conditions, ocean currents, and waves. The study uses field observation data and simulation results. The data is calculated to find Formzhal number based on the amplitude of tidal harmonic constants. The Flow analysis to determine the pattern and velocity of the current. The height and period of the wave to analyze characteristics of the wave. The results show that the tide in Kura-Kura Beach waters is a daily mix of a double with the highest tide at MSL and a minimum tide of 0.43 below MSL. While the current velocity obtained from the yield model has a range of (0.003 - 0.11) m/s, and the measurement results are between (0.005 - 0.14) m/s. The simulation results show that the current moves from land to sea at low tide, and it moves from sea to land at toward the tide. For the height of the ocean waves that are formed in a period of 10 years (2009 - 2019) ranges from (0.09 - 154) m and the wave period (1.86 - 5.73) seconds. Based on the calculation results, the largest wave energy occurs in the second intermediate period, namely 184.21 Joules/m with height and wave periods of 1.21 m and 4.39 seconds. In contrast, the smallest wave energy occurs in the first intermediate period with minimum wave height and period 0.18 m and 3.08 seconds. In general, based on the simulation of the current velocity model, the forecasting of wave height and wave energy in Kura-Kura Beach waters is still relatively small. So, it can be concluded that the location is still categorized as safe for coastal tourism and other activities.

scholarly journals Effect of Tides and Storm Surges on Storm Waves at the Northern Coastal Areas of Vietnam

2019 ◽  
Vol 35 (2) ◽  
Author(s):  
Nguyen Ba Thuy
Keyword(s):  
Storm Surge ◽  
Wave Height ◽  
Operating Time ◽  
Storm Surges ◽  
Wave Radiation ◽  
Observation Data ◽  
Ocean Engineering ◽  
Super Typhoon ◽  
Storm Waves ◽  
Storm Wave

Abstract: In this study, the effect of tides and storm surges on storm waves at the Northern coastal area of Vietnam is investigated by a coupled model of surge wave and tide (called: SuWAT). In particular, tide and storm surge are simulated by two-dimensional long wave equations taking into account the wave radiation stress, obtained from the SWAN model. The numerical was then applied to simulate storm waves and surges for typhoon Frankie (7/1996), Washi (7/2005) and Doksuri (9/2017). In the case of the super typhoon, the intensity of typhoon Washi is increased to level 16 (super typhoon level) but remains the same trajectory and operating time. The numerical results showed relatively well with observation data on storm surge and wave height. In general, the wave height is higher in the region near the coast and lower at offshore when considering the effect of tide and storm surge on storm wave. It also indicated that the effect of storm surge on storm wave is more significant than the tide. The results of the study are the basis for proposing to improve the wave forecasting technology in the study area. Keywords: Storm wave, tides, storm surge, super typhoon. References: [1] Đ. Đ. Chiến, N. B. Thủy, N.T. Sáo, T.H. Thái, S. Kim. Nghiên cứu tương tác sóng và nước dâng do bão bằng mô hình số trị, Tạp chí Khí tượng Thủy văn, 647 (2014) 19-24.[2] T.Q. Tiến, P.K. Ngọc. Kết nối mô hình SWAN với mô hình WAM thành hệ thống dự báo sóng biển cho vùng Vịnh Bắc Bộ, Tạp chí Khí tượng Thủy văn, 651 (2014) 21-26.[3] Y.Funakoshi, S.C.Hagen, P.Bacopoulos. Coupling of hydrodynamic and wave models: case study for Hurricane Floyd (1999) Hindcast, Journal of Waterway, Port, Coastal and Ocean Engineering, 134 (2008) 321 – 335.[4] S.Y. Kim, T. Yasuda, H. Mase. Wave set-up in the storm surge along open coasts during Typhoon Anita, Coastal Engineering, 57 (2010) 631-642.[5] X. Bertin, K. Li, A. Roland, and J.R. Bidlot. The contribution of short waves in storm surges: two recent examples in the central part of the bay of Biscay, Continental Shelf Research 96 (2015) 1-15.[6] H.Đ. Cường, N.B. Thủy, N.V. Hưởng, D.Đ. Tiến. Đánh giá nguy cơ bão và nước dâng do bão tại ven biển Việt Nam, Tạp chí khí tượng thủy văn, 684 (2018) 29-36.[7] Delf University of Technology. SWAN Cycle III Verion 40.31, User Guide. Delf, 2004.[8] N.B. Thủy, H.Đ. Cường, D.Đ. Tiến, Đ.Đ. Chiến, S.Kim. Đánh giá diễn biến nước biển dâng do bão số 3 năm 2014 và vấn đề dự báo, Tạp chí Khí tượng Thủy văn, 647 (2014).14-18.[9] N.B. Thuy, S. Kim, D.D. Chien, V.H. Dang, H.D. Cuong, C. Wettre and L. R. Hole. Assessment of Storm Surge along the Coast of Central Vietnam, Coastal researcher Journal, 33 (2017) 518-530.[10] V.H. Đăng, N.B. Thủy, Đ.Đ. Chiến, S. Kim. Nghiên cứu đánh giá định lượng các thành phần nước dâng trong bão bằng mô hình số trị, Tạp chí khoa học công nghệ biển. 17 (2017) 132-138.[11] T. Fujita. Pressure distribution within typhoon, Geophysical Magazine, 23 (1952). 437-451.

UNDERWATER BARRED BEACH PROFILE TRANSFORMATION UNDER DIFFERENT WAVES CONDITIONS

2017 ◽  
Author(s):  
Olga Kuznetsova ◽  
Olga Kuznetsova ◽  
Yana Saprykina ◽  
Yana Saprykina ◽  
Boris Divinsky ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Coastal Zone ◽  
Wave Height ◽  
Wave Energy ◽  
Wave Period ◽  
Beach Profile ◽  
Infragravity Waves ◽  
Wave Parameters ◽  
Mean Wave Period

Based on numerical modelling evolution of beach under waves with height 1,0-1,5 m and period 7,5 and 10,6 sec as well as spectral wave parameters varying cross-shore analysed. The beach reformation of coastal zone relief is spatially uneven. It is established that upper part of underwater beach profile become terraced and width of the terrace is in direct pro-portion to wave height and period on the seaward boundary but inversely to angle of wave energy spreading. In addition it was ascertain that the greatest transfiguration of profile was accompanied by existence of bound infragravity waves, smaller part of its energy and shorter mean wave period as well as more significant roller energy.

scholarly journals Physical Modelling of the Effect on the Wave Field of the WaveCat Wave Energy Converter

2021 ◽  
Vol 9 (3) ◽  
pp. 309
Author(s):  
James Allen ◽  
Gregorio Iglesias ◽  
Deborah Greaves ◽  
Jon Miles
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Wedge Angle ◽  
Wave Energy Converter ◽  
Wave Period ◽  
Surface Elevation ◽  
Energy Converter ◽  
Significant Wave ◽  
Model Scale

The WaveCat is a moored Wave Energy Converter design which uses wave overtopping discharge into a variable v-shaped hull, to generate electricity through low head turbines. Physical model tests of WaveCat WEC were carried out to determine the device reflection, transmission, absorption and capture coefficients based on selected wave conditions. The model scale was 1:30, with hulls of 3 m in length, 0.4 m in height and a freeboard of 0.2 m. Wave gauges monitored the surface elevation at discrete points around the experimental area, and level sensors and flowmeters recorded the amount of water captured and released by the model. Random waves of significant wave height between 0.03 m and 0.12 m and peak wave periods of 0.91 s to 2.37 s at model scale were tested. The wedge angle of the device was set to 60°. A reflection analysis was carried out using a revised three probe method and spectral analysis of the surface elevation to determine the incident, reflected and transmitted energy. The results show that the reflection coefficient is highest (0.79) at low significant wave height and low peak wave period, the transmission coefficient is highest (0.98) at low significant wave height and high peak wave period, and absorption coefficient is highest (0.78) when significant wave height is high and peak wave period is low. The model also shows the highest Capture Width Ratio (0.015) at wavelengths on the order of model length. The results have particular implications for wave energy conversion prediction potential using this design of device.

Motion Characteristics of Composite-Type Sea Cage under Pure Wave

2012 ◽  
Vol 490-495 ◽  
pp. 3405-3409
Author(s):  
Chun Liu Li ◽  
Yun Peng Zhao
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Vertical Motion ◽  
Data Acquisition System ◽  
Horizontal Motion ◽  
Wave Condition ◽  
Composite Type ◽  
Motion Range ◽  
Motion Characteristics ◽  
Sea Cage

To study motion range changes with wave condition and motion relationship between cages, physical model experiments were carried out. The authors designed 2 models of composite-type sea cages. Experimental data obtained by the CCD data acquisition system. The experiment results showed that 1.in the same period, horizontal motion range,vertical motion range and inclination changes of float collar increase with wave height; 2.In the same wave height, horizontal motion range of the float collar increases with period; 3.The laws between vertical motion and period are not obvious 4.The laws between inclination changes and period are not obvious 5.Motion range of the first cage along the direction of waves is less than other cages.

scholarly journals Historical variation and trends in storminess along the Portuguese South Coast

2011 ◽  
Vol 11 (9) ◽  
pp. 2407-2417 ◽  
Author(s):  
L. P. Almeida ◽  
Ó. Ferreira ◽  
M. I. Vousdoukas ◽  
G. Dodet
Keyword(s):  
Wave Height ◽  
Linear Increase ◽  
Annual Number ◽  
The North ◽  
Storm Wave ◽  
Using Data ◽  
The North Atlantic Oscillation ◽  
Historical Variation ◽  
Storm Characteristics ◽  
South Portugal

Abstract. This work investigates historical variation and trends in storm climate for the South Portugal region, using data from wave buoy measurements and from modelling, for the period 1952 to 2009. Several storm parameters (annual number of storms; annual number of days with storms; annual maximum and mean individual storm duration and annual 99.8th percentile of significant wave height) were used to analyse: (1) historical storminess trends; (2) storm parameter variability and relationships; and (3) historical storminess and its relationship to the North Atlantic Oscillation (NAO). No statistically significant linear increase or decrease was found in any of the storm parameters over the period of interest. The main pattern of storm characteristics and extreme wave heights is an oscillatory variability with intensity peaks every 7–8 yr, and the magnitude of recent variations is comparable with that of variations observed in the earlier parts of the record. In addition, the results reveal that the NAO index is able to explain only a small percentage of the variation in storm wave height, suggesting that more local factors may be of importance in controlling storminess in this region.

scholarly journals Performance of Linear Generator Designs for Direct Drive Wave Energy Converter under Unidirectional Long-Crested Random Waves

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5098
Author(s):  
Budi Azhari ◽  
Fransisco Danang Wijaya ◽  
Edwar Yazid
Keyword(s):  
Output Power ◽  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Analytical Calculation ◽  
Weight Ratio ◽  
Peak Frequency ◽  
Random Waves ◽  
Direct Drive ◽  
Significant Wave

For generating electricity, direct-drive wave energy converters (WECs) with linear permanent magnet generators (LPMGs) have advantages in terms of efficiency, simplicity, and force-to-weight ratio over WEC with rotary generators. However, the converter’s work under approaching-real wave conditions should be investigated. This paper studies the performance of a pico-scale WEC with two different LPMGs under unidirectional long-crested random waves. Different significant wave heights (using data in the Southern Ocean of Yogyakarta, Indonesia) and peak frequencies are tested. The JONSWAP energy spectrum is used to extract the wave elevations, while the MSS toolbox in MATLAB Simulink is employed to solve the floater’s dynamic responses. Next, the translator movements are extracted and combined with the flux distribution from FEMM simulation and analytical calculation, and the output powers are obtained. An experiment is conducted to test the output under constant speed. The results show for both designs, different tested significant wave height values produce higher output powers than peak frequency variation, but there is no specific trend on them. Meanwhile, the peak frequency is inversely proportional to the output power. Elimination of the non-facing events results in increasing output power under both parameters’ variation, with higher significant wave height resulting in a bigger increase. The semi iron-cored LPMG produces lower power loss and higher efficiency.

scholarly journals Wave transformation around breakwater (case study: tourism harbour, Eastern Bali, Indonesia)

2021 ◽  
Vol 894 (1) ◽  
pp. 012028
Author(s):  
M N Arsyad ◽  
O Setyandito ◽  
L M Kesuma ◽  
H D Armono ◽  
M Anda ◽  
...  
Keyword(s):  
Wave Height ◽  
Wave Transformation ◽  
Wave Condition ◽  
The Past ◽  
Design Wave Height ◽  
Coastal Modeling ◽  
Before And After ◽  
Modeling Software

Abstract An essential aspect in the sustainable design of breakwater is the determination of the design wave condition. It is predicted by utilizing severe wave conditions of the past 10 to 20 years. The tourism harbor at eastern Bali, Indonesia, is located where extreme wave condition occurs. Therefore, this research studies the wave height before and after constructing a breakwater in the harbor area. The wave height was simulated using numerical modeling. The methodology was performed by using the coastal modeling software of the SMS-CGWAVE model. The result shows the highest design wave height value of 3.9 m in the direction from the southeast. The design breakwater can reduce wave height up to 0.9 m or a 75.5% reduction. Further study is needed to simulate the extension of breakwater length to meet the criterion design of wave height in the harbor basin.

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