FIELD EXPERIMENT ON BEACH GRAVEL TRANSPORT

To examine the longshore transport processes of beach gravels under wave action, a field experiment was performed by tracing the dacite blocks injected on Fuji Coast, Shizuoka Prefecture, Central Japan. The mean dislocating velocity of the tracer was 2 to 3 m/day under normal sea conditions, while under storm conditions it reached about 400 m/day. This -velocity was fairly proportional to the longshore component of incident wave energy flux. The longshore variations of the size and shape of beach gravels were mainly resulted from the progressive attrition and impact breakage of beach gravels rather than from the selective transport.

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Evaluation of Incident Wave Energy in Flume Tests

Coastal Engineering 1986 ◽

10.1061/9780872626003.093 ◽

1987 ◽

Author(s):

Eliezer Kit ◽

Oded Gottlieb ◽

Dov S. Rosen

Keyword(s):

Incident Wave ◽

Wave Energy ◽

Flume Tests ◽

Incident Wave Energy

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Interannual variations of ice cover and wave energy flux in the northeastern Baltic Sea

Annals of Glaciology ◽

10.3189/2013aog62a228 ◽

2013 ◽

Vol 54 (62) ◽

pp. 175-182 ◽

Cited By ~ 2

Author(s):

Inga Zaitseva-Pärnaste ◽

Tarmo Soomere

Keyword(s):

Baltic Sea ◽

Wave Height ◽

Energy Flux ◽

Wave Energy ◽

Bulk Wave ◽

Wave Energy Flux ◽

The Mean ◽

A Site ◽

The Impact ◽

Wave Properties

AbstractThe major factor shaping the coast of the micro-tidal Baltic Sea is wave activity, the impact of which is limited by the presence or absence of sea ice. Existing studies have revealed almost no correlation between the annual mean wave height and the duration of the ice season. We attempt to evaluate the correlation between ice season duration and bulk wave energy flux (wave power), mean energy and average wave height over the ice-free season for three segments of the Estonian coast (Vilsandi, Pakri and Narva-Joesuu). Statistically significant correlation at the 95% confidence level exists between the duration of the ice season at Vilsandi (a site fully open to the predominant winds) and bulk wave energy flux derived from both observed and modelled wave properties. Similarly strong correlation exists between the mean wave energy and the duration of the ice season at the largely sheltered Narva-Joesuu site.

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Do longshore bars shelter the shore?

Journal of Fluid Mechanics ◽

10.1017/s0022112099007168 ◽

2000 ◽

Vol 404 ◽

pp. 251-268 ◽

Cited By ~ 34

Author(s):

JIE YU ◽

CHIANG C. MEI

Keyword(s):

Spatial Distribution ◽

Incident Wave ◽

Wave Energy ◽

Phase Relation ◽

Bragg Reflection ◽

Qualitative Change ◽

Numerical Calculations ◽

Reflected Waves ◽

Incident Waves ◽

Incident Wave Energy

In most past theories on Bragg reflection of waves by a finite patch of rigid bars, only outgoing waves are allowed on the transmission side, simulating the effect of an idealized shoreline where all the incident wave energy is consumed by breaking. In these theories the amplitudes of both the incident and reflected waves are found to decrease monotonically over the bar patch in the shoreward direction. This result has motivated the idea of artificially constructing bars to protect a beach from incident waves. However, some numerical calculations have suggested that this tendency does not always hold when there is some reflection from the shore. We show here that with finite reflection by the shoreline the spatial distribution of wave energy over the patch can indeed be reversed, indicating that the mechanism can increase the hazards to the beach. The phase relation between the bars and the shoreline reflection is found to be the key to this qualitative change of wave response.

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NEARSHORE SUSPENDED SEDIMENT LOAD DURING STORM AND POSXTSTORM CONDITIONS

Coastal Engineering Proceedings ◽

10.9753/icce.v17.70 ◽

1980 ◽

Vol 1 (17) ◽

pp. 70

Author(s):

Timothy W. Kana ◽

Larry G. Ward

Keyword(s):

Suspended Sediment ◽

Energy Flux ◽

Wave Energy ◽

Surf Zone ◽

Field Research ◽

Bulk Water ◽

Total Load ◽

Zone Width ◽

Longshore Transport ◽

Wave Energy Flux

As part of the DUCK-X experiment at the CERC field research facility at Duck, North Carolina in September, 1978, suspended sediment measurements were made along the CERC pier. In situ bulk water samples were collected during a moderate northeast storm and two days later during post-storm wave conditions. Concentrations varied from approximately 0.01 g/1 to over 10.0 g/1. Vertical arrays of suspended sediment samples indicated that concentration decreases rapidly up to two meters above the bed, then remains relatively constant, reflecting the nature of the suspension; intermittent suspension of sand near the bed, and continuous washload higher in the water column. Concentrations were at a maximum during storm conditions when measured values were 3 to 5 times higher than during non-storm conditions. The total load of sediment in a pier cross section during sampling periods in storm and post^storm conditions was calculated from arrays of 49 samples each. With H1/3 exceeding 2.3 HI and the surf zone width over 300 m during the storm, the total load of sediment in suspension was approximately 10 times higher than during poststorm conditions (Hi 73 - 1.2 m and surf zone width approximately 100 m) . Estimates of the longshore flux of suspended sediment indicate that as much as 60 times more sediment was transported during storm than during post-storm conditions. Longshore transport of sediment measured from 5 cm above the bed to the surface reached the equivalent of 22,330 m^/day. This value corresponds very closely to longshore transport predicted from wave energy flux. During post-storm conditions, on the other hand, transport of suspended sediment accounts for less than one-third of the transport predicted from wave energy flux.

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RESEARCHES ON SEA-WALLS

Coastal Engineering Proceedings ◽

10.9753/icce.v12.88 ◽

1970 ◽

Vol 1 (12) ◽

pp. 88

Author(s):

S. Nagal

Keyword(s):

Incident Wave ◽

Wave Energy ◽

Precast Concrete ◽

Recent Decade ◽

Point Of View ◽

Industrial Firms ◽

Wave Overtopping ◽

Port Facilities ◽

Sea Wall ◽

Incident Wave Energy

In the recent decade, very wide areas of sea where the depths of water are from several meters to ten meters or more during storms have been reclaimed for industrial firms and port facilities in many places in Japan As the incident wave energy in such cases is very large at the sea-walls, the protection of the reclaimed lands from wave overtopping by the conventional sea-walls of vertical type or composite-slope«and-berai type is generally impossible from an economical point of view In Japan a special type of sea-wall, which is of such a type that a rubble-mound covered with specially shaped precast concrete armor blocks is built in front of the sea-wall to absorb most of the incident wave energy, has been constructed to protect the reclaimed lands from wave overtopping Most of the seawalls have been proved satisfactory after passing of typhoons over or near the sea-walls The design of the sea-walls is presented here in by showing the comparisons between the experiments and prototypes during typhoons.

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Model Experiment on an OWC-Type Wave-Energy Converter With Hydraulic Power Take-Off

21st International Conference on Offshore Mechanics and Arctic Engineering, Volume 4 ◽

10.1115/omae2002-28171 ◽

2002 ◽

Cited By ~ 2

Author(s):

Torkel Bjarte-Larsson ◽

Per Magne Lillebekken ◽

Jo̸rgen Hals ◽

Johannes Falnes

Keyword(s):

Incident Wave ◽

Wave Energy ◽

Wave Energy Converter ◽

Laboratory Model ◽

Energy Converter ◽

Hydraulic Power ◽

Optimum Load ◽

Wave Channel ◽

Period 2 ◽

Incident Wave Energy

A wave-energy converter of the OWC type is described, in which the absorbed wave energy is converted to useful energy by means of a hydraulic power take-off. Means are provided to enable the float to be latched for phase control. The float is connected to a piston pump, which pumps water from the level of the water in the wave channel to a higher level, which is adjustable. By means of measurements from three wave gauges (two on the upstream side and one on the downstream side) the incident wave energy and the absorbed wave energy are derived. For a down-scaled laboratory model, resonance is obtained with an incident sinusoidal wave of period 1 s. With optimum load, the converted useful hydraulic energy is a fraction of 0.2 of the incident wave energy. The absorbed wave energy is then 0.6 units of the incident wave energy. With wave period 2 s and optimum load, these energy fractions are 0.03 and 0.13, which are increased to 0.05 and 0.21, respectively, when latching control is applied.

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Regularly-spaced grooves on shore platforms in north Northumberland, UK

Proceedings of the Yorkshire Geological Society ◽

10.1144/pygs2019-006 ◽

2020 ◽

Vol 63 (2) ◽

pp. 124-134

Author(s):

Alison M. Tymon ◽

Barry G. Tymon

Keyword(s):

Incident Wave ◽

Wave Energy ◽

Surf Zone ◽

High Water ◽

Edge Waves ◽

Shore Platform ◽

Bedding Planes ◽

High Water Mark ◽

Incident Wave Energy ◽

Shore Platforms

Unusual regularly-spaced grooves are found between low water mark (LWM) and high water mark (HWM) on several shore platforms in north Northumberland. References in the literature are sparse, so data were collected to establish the nature of the grooves and to elucidate the processes that might have formed them. Groove formation is confined to strata with widely spaced bedding planes on shore platforms dipping at no more than 5° towards the sea. The grooves are symmetrical, bifurcation is common and grooves on sandstones are deeper and more sinuous than those on limestones. Grooves at mid-tide levels are wider than grooves near LWM and HWM and the trend of the grooves is not related to joint trends. The process that has formed the characteristically smooth surfaces of the grooves is considered to be abrasion by sand and pebbles carried by waves in the surf zone of the shore platform. The width of the grooves is remarkably regular, and it is suggested that this may be due to the effects of the increase in incident wave energy given by edge waves.

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EVALUATION OF INCIDENT WAVE ENERGY IN FLUME TEST

Coastal Engineering Proceedings ◽

10.9753/icce.v20.93 ◽

1986 ◽

Vol 1 (20) ◽

pp. 93

Author(s):

Eliezer Kit ◽

Oded Gottlieb ◽

Dov S. Rosen

Keyword(s):

Least Squares ◽

Incident Wave ◽

Wave Energy ◽

Least Squares Method ◽

Stationary Wave ◽

Residual Energy ◽

Irregular Waves ◽

Wave Spectra ◽

Reflected Wave ◽

Incident Wave Energy

A two dimensional model study, carried out for a structure in a flume using irregular waves, presents the problem of determining the relationship between the total incident wave energy attacking the structure and its response to that attack (displacements, forces, etc.) in various sea states, The total incident wave energy can be evaluated indirectly only, because the wave energy measured in the flume contains an extent of residual wave energy in addition to that generated by the wave machine. This residual energy consists of the re-reflected wave energy from the paddle of the wave machine, assuming the existence of quasi-stationary wave conditions in the flume. A method originally presented by Gravesen et al. (1974), was applied in this study to evaluate the total incident wave energy. In view of the results obtained by this method, a physically more sound refinement is proposed for the evaluation of the total incident wave energy (and characteristic wave height). Results of model tests were analyzed by the CAMERI refinement and compared with the Gravesen method and with a cross-spectral least squares method, separating incident and reflected wave spectra from wave spectra measured in the flume, Good agreement was found between the results obtained employing the CAMERI refinement and the cross-spectral least squares method, Advantages and drawbacks of these methods are indicated,

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