Prediction of Beach Changes Due to Selective Discharge of Medium Sand during Storm Wave Conditions

Hydraulic model studies were conducted to aid in ascertaining the technical feasibility and optimum design factors of the perched beach concept. Among these were two-dimensional, movable-bed studies to determine an estimate of the amount of sand which would be lost seaward over the submerged toe structure by normal and storm wave action, the optimum elevation of the submerged toe structure, and the length of a stone blanket required to reduce seaward migration of sand to a minimum. The model beach was subjected to test waves until equilibrium was reached for a wide range of wave conditions for both the existing beach and the perched beach. Test results indicate that (a) little or no beachfill material will be lost seaward of the toe structure for normal wave conditions but the larger storm waves may cause erosion of the perched beach, (b) the installation of a stone blanket shoreward of the toe structure will reduce the amount of beach erosion, (c) if the beach fill is extended a sufficient distance seaward, the toe structure serves no useful purpose, and (d) a three-dimensional movable-bed model study is feasible and is necessary to determine the final design features of a perched beach.

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Storm Waves at the Shoreline: When and Where Are Infragravity Waves Important?

Journal of Marine Science and Engineering ◽

10.3390/jmse7050139 ◽

2019 ◽

Vol 7 (5) ◽

pp. 139 ◽

Cited By ~ 6

Author(s):

Oliver Billson ◽

Paul Russell ◽

Mark Davidson

Keyword(s):

Deep Water ◽

Water Wave ◽

Sandy Beach ◽

Transport Processes ◽

Infragravity Waves ◽

Storm Wave ◽

Wave Conditions ◽

Gravel Beaches ◽

Deep Water Wave ◽

Sand And Gravel

Infragravity waves (frequency, f = 0.005–0.05 Hz) are known to dominate hydrodynamic and sediment transport processes close to the shoreline on low-sloping sandy beaches, especially when incident waves are large. However, in storm wave conditions, how their importance varies on different beach types, and with different mixes of swell and wind-waves is largely unknown. Here, a new dataset, comprising shoreline video observations from five contrasting sites (one low-sloping sandy beach, two steep gravel beaches, and two compound/mixed sand and gravel beaches), under storm wave conditions (deep water wave height, H0 up to 6.6 m, and peak period, Tp up to 18.2 s), was used to assess: how the importance and dominance of infragravity waves varies at the shoreline? In this previously unstudied combination of wave and morphological conditions, significant infragravity swash heights (Sig) at the shoreline in excess of 0.5 m were consistently observed on all five contrasting beaches. The largest infragravity swash heights were observed on a steep gravel beach, followed by the low-sloping sandy beach, and lowest on the compound/mixed sites. Due to contrasting short wave breaking and dissipation processes, infragravity frequencies were observed to be most dominant over gravity frequencies on the low-sloping sandy beach, occasionally dominant on the gravel beaches, and rarely dominant on the compound/mixed beaches. Existing empirical predictive relationships were shown to parameterize Sig skillfully on the sand and gravel beaches separately. Deep water wave power was found to accurately predict Sig on both the sand and gravel beaches, demonstrating that, under storm wave conditions, the wave heights and periods are the main drivers of infragravity oscillations at the shoreline, with the beach morphology playing a secondary role. The exception to this was the compound/mixed beach sites where shoreline infragravity energy remained low.

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Estimating storm-wave conditions in San Francisco Bay

Transactions American Geophysical Union ◽

10.1029/tr028i002p00271 ◽

1947 ◽

Vol 28 (2) ◽

pp. 271 ◽

Cited By ~ 4

Author(s):

J. A. Putnam

Keyword(s):

San Francisco ◽

San Francisco Bay ◽

Storm Wave ◽

Wave Conditions

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NUMERICAL STUDY OF NEARSHORE HYDRODYNAMICS UNDER STORM WAVE CONDITIONS IN HUJEONG BEACH, EAST COAST OF KOREA

Coastal Engineering Proceedings ◽

10.9753/icce.v36.currents.67 ◽

2018 ◽

pp. 67

Author(s):

Yeon S. Chang ◽

Jong Dae Do ◽

Kyungmo Ahn ◽

Jae-Youll Jin

Keyword(s):

Numerical Model ◽

East Coast ◽

Surf Zone ◽

Numerical Study ◽

Navier Stokes ◽

Model Study ◽

Suspended Sediment Concentrations ◽

Storm Wave ◽

Wave Conditions ◽

The Republic

In this study, we present the results of numerical model study to simulate the hydrodynamic conditions observed in Hujeong Beach in the east coast of the Republic of Kore from December, 2016 to January, 2017 during which several extratropical cyclones hit the area causing extreme wave conditions. Three acoustic instrumentation systems were moored from the coast to a location outside the surf zone where the water depth was ~8m to measure waves, currents and suspended sediment concentrations. For the numerical model, we employed the CADMAS-SURF Raynolds-Averaged Navier-Stokes (RANS) model to generate the wave conditions over the region of the field experiment.

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A Simple Nozzle-Diffuser Duct Used as a Kuroshio Energy Harvester

Processes ◽

10.3390/pr9091552 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1552

Author(s):

Po-Hung Yeh ◽

Shang-Yu Tsai ◽

Wei-Ren Chen ◽

Shing-Nan Wu ◽

Meng-Chang Hsieh ◽

...

Keyword(s):

Energy Demand ◽

Energy Harvester ◽

Normal Wave ◽

Sea Surface ◽

Ocean Current ◽

Ansys Fluent ◽

Wave Condition ◽

Storm Wave ◽

Wave Conditions ◽

The Kuroshio

In response to the increasing energy demand in Taiwan and the global trend of renewable energy development, Kuroshio energy is a potential energy source. How to extract this invaluable natural resource has then become an intriguing and important question in engineering practices. This study reported the results of a feasibility study for a nozzle-diffuser duct (NDD) as the Kuroshio currents energy harvester. The computational fluid dynamics (CFD) software ANSYS Fluent was employed to calculate the drag and added mass coefficients of the duct anchored to the seabed. Those coefficients were further imported into Orcaflex to simulate the motion of the duct under normal and storm wave conditions. Results showed that the duct was stable 25 m below the sea surface under normal wave conditions. When the wave condition changed to storm waves, the duct needed to dive into at least 90 m below the sea surface to regain its stability and obtain high power take-off (PTO). An optimal design nozzle-diffuser-duct was reported, and a PTO peak of 15 kW was expectable in the Kuroshio currents. Once a suitable offshore platform can be developed with sixty-six NDDs, a Megawatt Kuroshio ocean current power generation system is feasible in the near future.

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ON THE INITIATION OF NEARSHORE MORPHOLOGICAL RHYTHMICITY

Coastal Engineering Proceedings ◽

10.9753/icce.v32.sediment.47 ◽

2011 ◽

Vol 1 (32) ◽

pp. 47

Author(s):

Matthieu Andreas De Schipper ◽

Roshanka Ranasinghe ◽

Ad Reniers ◽

Marcel Stive

Keyword(s):

Numerical Model ◽

Wave Period ◽

Wave Group ◽

Initiation Time ◽

Length Scales ◽

Long Wave ◽

Storm Wave ◽

Wave Conditions

Nearshore rhythmicity is often initiated in the period just after a storm where the subtidal bar is turned alongshore uniform. The initiation time as well as the length scales of the created rhythmicity varies from one storm period to another. Here we show that the post-storm wave conditions are related to the initiation of the morphological rhythmicity. Narrow-banded and long wave period, both proxies for swell waves, are often found to be present priorto the initiation of rhythmicity. Furthermore, numerical model computations illustrate that swell waves induce significantly larger wave group induced velocities on the bar. These findings imply that the arrival of swell waves can initiate and stimulate the nearshore morphological rhythmicity.

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Observation of nearshore crescentic sandbar formation during storm wave conditions using satellite images and video monitoring data

Marine Geology ◽

10.1016/j.margeo.2021.106661 ◽

2021 ◽

pp. 106661

Author(s):

Jong Dae Do ◽

Jae-Youll Jin ◽

Weon Mu Jeong ◽

Byunggil Lee ◽

Chang Hwan Kim ◽

...

Keyword(s):

Satellite Images ◽

Video Monitoring ◽

Monitoring Data ◽

Storm Wave ◽

Wave Conditions

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CALCULATED SAND FILLS AND GROIN SYSTEMS

Coastal Engineering Proceedings ◽

10.9753/icce.v13.72 ◽

1972 ◽

Vol 1 (13) ◽

pp. 72

Author(s):

John S. Hale

Keyword(s):

Los Angeles ◽

Wave Action ◽

Natural Wave ◽

Plan View ◽

Empirical Information ◽

Beach Width ◽

Sand Supply ◽

Storm Wave ◽

Average Wave ◽

Wave Conditions

This paper demonstrates the results of the comparison between the calculated alignment of the beach's plan view end the actual alignment that resulted from the natural wave action. A new groin system was designed to replace an existing one, Th? new groin system and spacing ujas designed to hold the beach fill at the required width during average wave conditions as well as changing storm wave conditions. The system was designed for Las Tunas Beach, a beach near Los Angeles, California, In other words, the energies are tabulated for all storm conditions, and the beach alignment is recalculated for changing storm conditions. As the beach plan view alignment rotates back and forth with changing storm directions, it must always meet the minimum beach width requirements. This may entail changing the groin lengths, heights and spacing several times before the design complied with all requirements. Surveys from 1929 to 1970 showed that the beach did not have long periods., periods of several years, of constant ernsion or constant accretion. If there are no major man made changes, it is safe to assume that nature will provide an ad^ruate sand supply. L=s + , but not. least, the calculated beach alignments check with the empirical information gathered from years of survey;ng.

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Coupled Dynamics Simulation of Submerged Floating Tunnel for Various System Parameters and Wave Conditions

Volume 7A: Ocean Engineering ◽

10.1115/omae2018-78687 ◽

2018 ◽

Author(s):

Chungkuk Jin ◽

Joseph Moo-Hyun Kim ◽

Junho Choi ◽

Woo-Sun Park

Keyword(s):

Weight Ratio ◽

Dynamics Simulation ◽

Nonlinear Phenomena ◽

Random Waves ◽

System Parameters ◽

Storm Wave ◽

Submerged Floating Tunnel ◽

Wave Conditions ◽

Elastic Modes ◽

Fixed End

Coupled dynamic analyses of 900-m-long SFT (submerged floating tunnel) are conducted for various system parameters and random waves. The SFT dynamics between the clamped-clamped fixed-end conditions are caused by elastic modes, and thus hydro-elasticity simulation program has been modeled, from which various elastic modes and wet natural frequencies are identified. Parametric studies are conducted to investigate SFT horizontal and vertical motions and mooring tensions with varying SFT bending stiffness, mooring interval, mooring material, and 100-yr-storm-wave conditions. The BWR (buoyancy to weight ratio) and water depth are fixed to be 1.3 and 80 m. Various nonlinear phenomena including larger downward motion and the corresponding mooring snap loading are observed and discussed.

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