scholarly journals TWO-DIMENSIONAL EMPIRICAL EIGENFUNCTION MODEL FOR THE ANALYSIS AND PREDICTION OF BEACH PROFILE CHANGES

1986 ◽  
Vol 1 (20) ◽  
pp. 87 ◽  
Author(s):  
T.W. Hsu ◽  
S.R. Liaw ◽  
S.K. Wang ◽  
S.H. Ou
Keyword(s):  
Breaking Waves ◽  
Relative Importance ◽  
Two Dimensional ◽  
Coastal Structures ◽  
Beach Profile ◽  
Radiation Stress ◽  
Profile Data ◽  
Profile Changes ◽  
D Model ◽  
Profile Change

A two-dimensional empirical eigenfunction model is proposed for the analysis and the prediction of beach profile change due to longshore and cross-shore sediment transports. Beach profile data from Redhill coast, Taiwan, measured every two months at 150 meters interval along the detached breakwaters are analyzed and the relative importance from two directions is investigated. Furthermore, by employing the method of Markov process and linear regression, a prediction model is formulated which takes into account the effect of breaking waves, bottom sediment and radiation stress of waves. This 2-D model is shown to be effective in the analysis and the prediction of beach changes near the coastal structures.

scholarly journals DESCRIPTION OF BEACH CHANGES USING AN EMPIRICAL PREDICTIVE MODEL OF BEACH PROFILE CHANGES

1982 ◽  
Vol 1 (18) ◽  
pp. 86 ◽  
Author(s):  
Takaaki Uda ◽  
Hiroshi Hashimoto
Keyword(s):  
Predictive Model ◽  
Sand Transport ◽  
Coastal Structures ◽  
Beach Profile ◽  
Profile Data ◽  
Longshore Transport ◽  
Profile Changes ◽  
Offshore Transport ◽  
Eigenfunction Method ◽  
Profile Change

In order to analyze beach profile changes due to longshore and onshore-offshore sand transport, here is proposed a new model named the "empirical predictive model of beach profile change", which is an application of the empirical eigenfunction method. The analysis of the profile data obtained at the Misawa fishery port in Ogawarako Coast over five years from 1973 to 1977 indicates that profile changes due to longshore transport and to onshore-offshore transport can be separated. The model is shown to be effective in the analysis of profile changes near coastal structures.

scholarly journals EXPERIMENTS ON BEACH PROFILE CHANGE WITH A LARGE WAVE FLUME

1982 ◽  
Vol 1 (18) ◽  
pp. 85 ◽  
Author(s):  
Ryoichi Kajima ◽  
Takao Shimizu ◽  
Kohki Maruyama ◽  
Shozo Saito
Keyword(s):  
Simple Model ◽  
Transport Rate ◽  
Sand Transport ◽  
Two Dimensional ◽  
Beach Profile ◽  
Large Wave ◽  
Wave Flume ◽  
Grain Sizes ◽  
Profile Changes ◽  
Profile Change

Two-dimensional beach profile changes were investigated with a newly constructed prototype-scale wave flume. The flume is 205 m long, 3.4 m wide and 6 m deep. Sand of two grain sizes was used in the experiments. Analysis of the results was made through use of the parameter C, introduced by Sunamura and Horikawa (1974) to classify beaches as either erosional and accretionary. Beach profile changes obtained in the flume were similar to those in the prototype (field). Net sand transport rate distributions were classified into five types, two of which do not seem to have been observed in laboratory (smallscale) experiments. A simple model describing the five types was developed for evaluating two-dimensional beach profile changes.

scholarly journals SEDIMENT TRANSPORT AND BEACH TRANSFORMATION

1982 ◽  
Vol 1 (18) ◽  
pp. 88 ◽  
Author(s):  
Tomoya Shibayama ◽  
Kiyoshi Horikawa
Keyword(s):  
Sediment Transport ◽  
Wave Motion ◽  
Wave Theory ◽  
Linear Wave ◽  
Two Dimensional ◽  
Beach Profile ◽  
Field Investigations ◽  
Transport Calculation ◽  
Profile Changes ◽  
Profile Change

Laboratory and field investigations were performed in order to formulate a predictive model of two-dimensional beach profile change. The observed transport was classified into six types, and transport formulas were deduced for each type based on a microscale description of sediment movement caused by wave action. A numerical model of two-dimensional beach transformation was then developed. Beach profile changes calculated with the model were then compared with the laboratory results. The model was found to give reasonable results except in the vicinity of the wave plunging point. The sediment transport calculation is based on a sinusoidal velocity profile. The model appeares to give good results as long as the wave motion can be reasonably approximated by linear wave theory.

scholarly journals NUMERICAL SIMULATION OF BEACH PROFILE CHANGES

1986 ◽  
Vol 1 (20) ◽  
pp. 106
Author(s):  
Hitoshi Nishimura ◽  
Tsuguo Sunamura
Keyword(s):  
Numerical Simulation ◽  
Surf Zone ◽  
Wave Profile ◽  
Wave Transformation ◽  
Two Dimensional ◽  
Beach Profile ◽  
Profile Changes ◽  
Wave Shoaling ◽  
Profile Change ◽  
Dimensional Wave

This paper presents an overall numerical model for predicting beach profile changes due to waves. The local rate of net on/offshore sediment transport is empirically formulated as a function of the Ursell number and Hallermeier parameter. A sub-model of two-dimensional wave transformation includes the wave shoaling, breaking and damping in a surf zone. It is combined with another sub-model of beach profile change for the analyses of wave-profile interaction. The validity of the model is examined through hindcasting of profile changes observed in ordinary and prototype-scale flumes.

scholarly journals LABORATORY STUDY ON TWO-DIMENSIONAL BEACH TRANSFORMATION DUE TO IRREGULAR WAVES

1986 ◽  
Vol 1 (20) ◽  
pp. 102 ◽  
Author(s):  
Nubuo Mimura ◽  
Yukinori Otsuka ◽  
Akira Watanabe
Keyword(s):  
Wave Train ◽  
Irregular Waves ◽  
Two Dimensional ◽  
Beach Profile ◽  
Irregular Wave ◽  
Sand Ripple ◽  
Ripple Formation ◽  
Sand Movement ◽  
Incident Waves ◽  
Profile Change

In the present study, effects of irregular waves on two-dimensional beach transformation and related phenomena were investigated through a series of laboratory experiments. Attempts were made to determine a representative wave of irregular wave trains which controlled individual phenomenon related to the two-dimensional beach profile change. It was found that the representative wave is different for each phenomenon. For the macroscopic beach profile change, it is the mean wave which represents whole incident waves. On the other hand, some of microscopic phenomena, such as initiation of sand movement and sand ripple formation, are controlled by larger waves in the wave train selectively, of which representative wave is the significant wave.

scholarly journals LABORATORY STUDY OF SCALE EFFECTS IN TWO-DIMENSIONAL BEACH PROCESSES

2011 ◽  
Vol 1 (8) ◽  
pp. 14 ◽  
Author(s):  
Yuichi Iwagaki ◽  
Hideaki Noda
Keyword(s):  
Wave Height ◽  
Scale Effects ◽  
Breaking Waves ◽  
Two Dimensional ◽  
Sediment Size ◽  
Beach Processes ◽  
Time Period ◽  
Equilibrium Profile ◽  
Profile Changes ◽  
Constant Slope

In order to disclose the essential relationship between the beach processes and wave characteristics, two dimensional model tests are often performed for beach profile changes due to incident breaking waves normal to the beach. In applying the results of such experiments to the prototype of beaches, the scale effects of waves and sediments on the beach processes with equilibrium beach profiles should necessarily be considered. In this paper, as an approach to solve this problem in two dimensional beach studies, the effects of wave height and sediment size on the shore line movement and equilibrium beach profiles are discussed based on the results of experiments made by the authors and other experiments with smaller and larger scales by some researchers. It has been found that the ratio of wave height to sediment diameter is a very significant factor in this problem. In addition, the changes m a character of breaking waves during the time period of wave action from the beach having an initial constant slope to that with an equilibrium profile are presented.

scholarly journals INFLUENCES OF CLIMATE CHANGE ON BEACH PROFILE

2012 ◽  
Vol 1 (33) ◽  
pp. 17
Author(s):  
Kentaro Hayashi ◽  
Nobuhito Mori ◽  
Hajime Mase ◽  
Yoshiaki Kuriyama ◽  
Nobuhisa Kobayashi
Keyword(s):  
Climate Change ◽  
Wave Parameter ◽  
Characteristic Change ◽  
Beach Profile ◽  
Profile Data ◽  
Wave Characteristics ◽  
Equilibrium Beach Profile ◽  
The Relationship ◽  
Profile Change

The influences of climate change due to global warming have been estimated on not only sea level rise but also wave characteristics such as height or energy flux. In this study, the characteristics of medium and long term beach profile change is investigated based on the observed beach profile data at HORS for past 24 years and the relationship between the wave characteristics observed at Kashima port and the climate indexes. In order to estimate the influences of the medium and long term wave characteristic change, a theory is introduced based on equilibrium beach profile with wave parameter, which is theoretically based on sediment characteristic. Moreover, the validation of the theory is evaluated based on the observed beach profile data and wave data.

scholarly journals BEACH PROFILES AND ON-OFFSHORE SEDIMENT TRANSPORT

1980 ◽  
Vol 1 (17) ◽  
pp. 67 ◽  
Author(s):  
Akira Watanabe ◽  
Yoshihiko Riho ◽  
Kiyoshi Horikawa
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Laboratory Test ◽  
Test Data ◽  
Critical Shear Stress ◽  
Two Dimensional ◽  
Bottom Shear Stress ◽  
Beach Profile ◽  
Profile Changes ◽  
Sloping Beach

The on-offshore sediment transport due to waves on a sloping beach is studied by analyzing the laboratory test data on two-dimensional beach deformation. The net rates of sediment transport both inside and outside the breaker zone are evaluated from beach profile changes and are related to the nondimensional bottom shear stress or the Shields parameter. The importance of the critical shear stress and of asymmetrical to-and-fro water partical motion near the bottom is pointed out.

scholarly journals ONSHORE-OFFSHORE TRANSPORT AND BEACH PROFILE CHANGE

1980 ◽  
Vol 1 (17) ◽  
pp. 71 ◽  
Author(s):  
Masataro Hattori ◽  
Ryoichi Kawamata
Keyword(s):  
Gravitational Force ◽  
Surf Zone ◽  
Breaking Waves ◽  
Time Parameter ◽  
Sand Transport ◽  
Bottom Slope ◽  
Beach Profile ◽  
Physical Consideration ◽  
Offshore Transport ◽  
Profile Change

In this paper a model is presented to describe onshore-offshore sand transport in the surf zone. The model is based on the physical consideration that when the net transport attains a state of equilibrium, the power expended through gravitational force in suspending sand grains is balanced by that due to the uplifting force arising from the turbulence generated by breaking waves. Two important parameters controlling sand transport are the dimensionless fall-time parameter and bottom slope.

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