Large eddy simulation for granular-fluid in sheet-flow regime under oscillatory flow has been performed by using the solid-liquid two-phase flow model based on the Euler-Lagrange coupling. Rheological characteristics of sheet-flow layer where frequent inter-granular collisions occur has been investigated computationally. The simulated particle system is verified by comparison with the previous experimental results. Then the transitional area in the sheet-flow layer satisfying Bagnold's law is highlighted. And active inter-granular collisions are found by decreasing of the period of oscillation under the same bottom shear stress condition.

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Medical X-ray CT scanner was applied to dynamic measurements of beach profile changes and sediment transport during wave actions. Reconstructing three-dimensional images using Hounsfield Units (HU), the evolutions of beach morphology were examined. Both of Rouse and exponential profiles of time-averaged sediment concentrations are not good skill to show the measured profile of sediment concentrations using X-ray CT. The profile of eddy diffusivity was estimated using the 1D diffusion equation for steady state and measured CT results. Estimated profile of eddy diffusivity in the surf zone was good agreement with the model proposed by Christoffersen.Jonsson (1985).

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The topography change model that considered the sediment suspension by the wave breaking attenuation was developed. This model has following features: The average surface elevation in an initial shoreline and the height of wave run-up are a little large compared with an existing empirical equation. The sediment suspension in the run-up region is considered. It is necessary to adjust the relation coefficient between wave breaking attenuation and sediment suspension by using the experiment or the field observation result.

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To extend the current version of the tidal flat model, ECOMSED+COSINUS, can be applied to the local practical problems, the modeling of consolidation and high concentration mud flow considering the sediment erosion and deposition processes should be developed. In order to distinguish solid bed from the fluidized bed we defined the limit deposition strength of consolidation layer by using the yield stress of Bingham plastic mud. Including this idea, this study proposed a revised erosion-deposition model for the tidal flat sediment transport with consideration of flocculation, concentrated benthic suspension flow and bed consolidation of cohesive and non-cohesive sediment.

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A new model for predicting beach changes was developed using the cellular automaton method, taking sand transport under the ongoing and outgoing waves into account independently. The model was applied to predict sand deposition on the backshore with a steep foreshore slope on the Oiso coast. Furthermore, three-dimensional topographic changes were predicted using the model, when a groin with an opening between the landward end of the groin and the land was constructed on a beach. The predicted beach changes well explained the observation results on the Osawa coast facing the Uraga Strait.

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Ajigaura Beach is one of the famous bathing beaches in Ibaraki Prefecture. In recent years, severe beach erosion has occurred. Even though beach nourishment has been carried out as a measure against beach erosion, wave run-up damage often occurred in the south part of the beach where the foreshore was narrowed. In this paper, topographic changes of the beach were investigated on the basis of the past aerial photographs and bathymetric survey data, and the numerical simulation using the BG model was carried out to reproduce the measured beach changes. The measured and calculated results were in good agreement.

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Many beach deformation models have been developed over the recent decades. Among them, there were a few models which could simulate field-scale beach deformation based on local transport rate in natural sea conditions. This paper aims to re-evaluate former work of sand transport formulae and to develop a comprehensive Quasi-3D Large Scale Beach Deformation Model. In this paper, three sand transport formulae, Shibayama et al. (1982), Sunamura(1982) and Watanabe et al. (1984) were examined. The limit parameter ∏c which was proposed by Watanabe et al. was explained by using Sunamura and Horikawa's (1974) parameter C. Finally the model results of beach deformation model were compared with the Seisho Beach data in 2007.

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A short-term swash zone beach profile change model proposed by Suzuki and Kuriyama (2009) focusing on berm formation and erosion was improved using the distribution curves of cross-shore sediment transport rates for berm formation and erosion determined by the slope of the curves at the inflection points. The improved model was applied to the calculation of three months beach profile change, which results were compared with field data and the computational results of Suzuki and Kuriyama (2009). The present model was found to well predict not only the shoreline change but also the beach profile change, including the berm formation and erosion, compared to the model by Suzuki and Kuriyama (2009).

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The wave-induced evolution of the surface profile of an artificial shallow is investigated experimentally in terms of temporal changes in bottom flow velocity on the surface of the shallow and pore-water pressure inside the surface layer of the shallow. Experimental results show that the relative vertical effective stress ratio is always negatively correlated with the Shields parameter defined as positive landward, and suggest that offshore sediment transport can be accelerated regardless of the profile evolution of the shallow. Moreover, it is found that sediment transport on the shallow can always be assessed reasonably well using a Shields parameter modified to consider pore-water pressure on the surface layer of the shallow, and consequently the consideration of the pore-water pressure is essential to assess the topographic change of the shallow.

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In the case where soft bottom mud with high water content is fluidized by wave-induced pressure, cracks are generated in the surface of the mud. In order to examine the behavior of sandy mud under wave action, a laboratory experiment has been conducted in a condition that sediment is fluidized and cracks are generated in the surface. It is found that water content of sandy mud is remarkably decreased under wave action by not only consolidation but washout of clay particles, which contain significant amount of water, from the mixture sediment. The characteristics of sediment transport of sandy mud are clarified in comparison with the experimental results on genuine mud reported by a conventional study. Also, it is found that resonant fluidization response occurs in sandy mud causing energy dissipation of surface waves.

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The flow properties of marine clays, the water content of which are much larger than the liquid limit are studied experimentally. A series of vane shear tests and rotary viscometer tests were carried out with four marine clays with different water contents larger than the liquid limit. It was found that the yield stresses obtained by the viscometer were closely related with the water contents normalized by liquid limit. Using water content normalized by the liquid limit, a unique relationship between shear stress and shear rate is obtained. As a result, it was known that the flow properties of marine clays with high water content can be estimated by knowing the normalized water content or vane shear strength. These findings are useful to consider the wave-mud interaction problem.

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The mechanism of morphology change at the first (western) entrance of lake Saroma were investigated with the 20 years bathymetric survey data set. It shows that the volume around the entrance decreased after the east jetty construction started and the major morphology changes were erosion along the channel and movement of ebb shoal. A numerical model which aimed to predict the morphology change for several years was developed based on the sediment transport characteristics. The simulation result shows that this model can quantitatively reconstruct the observed morphological changes for 3-4 years.

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Morphological changes behind a submerged breakwater on the Niigata Coast were investigated using a shoreline prediction model and the Empirical Orthogonal Function (EOF) analysis. The shoreline in the study area retreated at a rate of 4.1 m/year from 2001 to 2007, but it was stable from 2007. The measured shoreline change was reproduced by a shoreline prediction model in which the shoreline change rate was assumed to be a function of the offshore wave energy flux and the shoreline position. The comparison between the shoreline hindcast results and the modes 1 and 2 obtained by EOF analysis showed that the shoreline change estimated using the offshore wave energy flux corresponded to the shoreline change in mode 1, while the shoreline change estimated using the shoreline position corresponded to that in mode 2.

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This study focuses on the morphodynamics in the opening of artificial reefs. The morphodynamics around the artificial reefs in the Uradome Beach, Tottori, were analyzed from survey results. The scour in the opening of the reefs were remarkably occurred due to extension of the crown-height and width of the reefs. In order to clarify the mechanism of the scour, the hydrodynamic characteristics in the opening of the reefs were examined by the laboratory experiments, and the morphodynamics around the reefs in the Uradome Beach were investigated using three-dimensional beach evolution model. From the results of experiments and numerical simulations, it was found that a cause of the scour of the opening was due to strong rip-currents generated by the extension of the crown-height.

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This study intends to understand seabed topography change around submerged breakwaters. By using long-term observation data obtained at Fukui-kou coast and Niigata-kou coast, the topography change around submerged breakwaters has been verified. The observation data for verification are bathymetric survey data and current observation data around the submerged breakwaters. The results of bathymetric data analysis indicate that the belt-shaped scour behind the submerged breakwaters has been formed in accordance with the construction process. It is also confirmed that the dominant current pattern around the submerged breakwaters is consistent with the pattern of topography change after installation of submerged breakwaters.

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The responses of the shoreline change to cyclic tidal changes were investigated by the spectral analysis using FFT method and a multivariate autoregressive model. The shoreline data set were obtained for 25 years at Hazaki Oceanographical Research Station (HORS) facing the Pacific Ocean. The power spectrum densities showed shoreline changes with a period of 14.76 days, which is the spring-neap cycle of the tide. The relative power contribution analysis showed the tidal range affects the shoreline change rate as the main factor of 14.76 days cyclic variability, and it was indicated the mechanisms are due to the effects of the seawater percolation and the groundwater effluent by the difference between the water table and the tidal level.

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This study highlights recovery of sandy coasts and river mouths in Miyagi Prefecture after severe erosion due to The 2011 Great East Japan Earthquake Tsunami, based on a field investigation and aerial photograph analysis. It is found that the duration required for morphology recovery is highly dependent on the length of surrounding sandy coast supplying sediment. In addition, one-line model is applied to reproduce this recovery process. Although complete agreement cannot be achieved as compared with the measurement, qualitative agreement is obtained for the relationship between the recovery time and the ratio between the length of sandy coast and the breaching width. The findings of this study may be useful for preparing for tsunami disaster prevention and preparedness.

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On a flat shallow seabed, sand spits and cuspate forelands with rhythmic shapes may develop and a barrier island can elongate alongshore which significantly differs from the beach changes on coasts facing a deep ocean. In this study, the interaction between two circular islands on a flat shallow seabed due to waves was investigated by the numerical simulations, focusing on the wave-sheltering effect of the islands themselves. The topographic changes caused by the interaction between two sandy islands were predicted using the BG model.

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On March 11, 2011, the Great Tsunami hit the northeast Japan's coasts, causing severe disaster along the coastline. The river mouth bar of the Same River flowing into a pocket beach with 6.5 km length bounded by Point Ryugu and Nakoso fishing port on the north and south ends, respectively, was eroded and disappeared by the return currents of tsunami. Simultaneously ground subsidence by 0.5 m occurred due to the earthquake in this area. In this study, the shoreline changes of this pocket beach after the tsunami and ground subsidence were investigated using aerial photographs and bathymetric survey data. It was found that the recovery of the river mouth bar caused beach erosion on the nearby coasts.

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Erosion of sand dune was investigated on Miyazaki Coast located east side of the Kyushu Island facing the Pacific Ocean. The erosion has been significant since early 1980's and accelerated since 1994. The average speed of the dune retreat was estimated at 2m/year recently accompanied with the gradual decrease of the dune height. The dune erosion in 2011 was found to be due to successive attack of three typhoons. The erosion was observed to be most significant by Typhoon No. 12 attacked in August. Combined effects of successive high waves to nearshore topography as well as long duration of high waves appeared to be influential to the erosion.

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This study investigates the river mouth morphology changes at the Nanakita River mouth. The river mouth was greatly changed due to The Great East Japan Tsunami in 2011. The gradual process of river mouth changes was investigated using water level measurement data in the river and the sea. The correlation coefficient and the linear gradient between the two data sets were analyzed. Both of the parameter show that the river mouth morphology changes will have significant effects to the tide intrusion, hence their value will correspond to the river mouth condition. River mouth closure, as well as river mouth opening has been successfully detected. The proposed method in this study will provide an efficient way for analyzing and evaluating river mouth morphology changes.

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This study focuses on sediment budgets and resulting coastal morphology changes around Kalpitiya district, northwest of Sri Lanka, through analysis of satellite data, aerial photograph and applications of numerical models. Satellite images, mainly based on ALOS PALSAR data, were used for both the long-term and short-term monitoring of shoreline profiles. Wave forecasting model, WAM, was applied for estimation of the offshore wave conditions. These newly obtained data was then introduced to the shoreline model for predictions of observed shoreline changes. It was found through the analysis that alongshore sediment budget are strongly dependent on local allocation of coral reaves, which trap the sediment, and onshore sediment transport due to overtopping waves across the low-elevated sand spit during the storm.

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Characteristics of ground deformation are surveyed from the data of triangulation point, bench mark, permanent GPS monument and tide level, in east area of Hokkaido. The rate of subsidence in east area of Hokkaido is high, especially, is 1.36cm/year in Notsuke peninsula. The change velocity of tide level is almost constant in the long term. In the area that has high velocity of tide level change, the effect of sea level rise is relatively small, and change velocity of tide level is almost equal to that of subsidence. In Notsuke peninsula, the erosion of coastal area is a serious problem. About quarter of coastal erosion in Notsuke peninsula is caused by subsidence.

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The numerical analysis by LES was carried out for the flow and topography change around the Shiogama(namely the deepest region) near Yo Shima during eastward and westward current. The flow accelerates and diverges radially during the westward current and converges during the eastward current near the top of slope around Shiogama. These numerical results accord with the measured results by ADP. The scour rate during eastward-westward current is approximately same to it during westward-eastward current. However, the scour rate during eastward current is more than it during westward current. So, the eastward current contributes to the topography change near the Shiogama.

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Point Futtsu is the cuspate foreland separating Tokyo Bay and the Uraga Strait. In recent years, the shoreline around this cuspate foreland is considered to be stable, but large-scale seasonal variation may occur because wave direction at the tip of the cuspate foreland reverses seasonally. In the previous studies, however, such seasonal variation in beach topography has not been studied. We measured the seasonal variation of the shoreline configuration around the tip of the sand spit and the topographic response to incident waves was investigated by field observation. A large sand spit formed before June 11, 2011 was markedly deformed due to the action of predominant waves incident from the direction of NNW in Tokyo Bay. This sand spit was assumed to be formed by the action of the 2011 Great Tsunami.

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Bathymetric changes around the Tenryu River mouth were analyzed using the narrow-multi beam survey data taken eight times between 2008 and 2010. In 2010 four large floods with a daily discharge greater than 1000 m³/s occurred, 4.0 × 10⁵ m³ of sand was deposited while forming a river mouth terrace immediately offshore of the mouth. In addition, because calm wave condition continued between 2008 and 2010, seabed was eroded in the zone deeper than -6 m, whereas in the zone shallower than -6 m sand was deposited due to the shoreward sand transport, which prevailed under the calm wave conditions.

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The beach topography around the detached breakwaters of the Ryuyo coast located immediately east of the Tenryu River mouth was observed to investigate the beach changes. On the basis of the aerial photographs and bathymetric survey data taken since 2007, beach changes in the area between the detached breakwaters and the river mouth were analyzed. 5 m³ of color sand was placed at the shoreline and subsequent dispersion of the color sand along the shoreline was measured. The detached breakwaters were found to be the solid boundary at present, although eastward longshore sand transport existed in the past, because of decrease in sand supply from the river mouth.

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Recently, flood shoals have been developed at the entrance of the Toufutsu Lake located along Okhotsk Sea in Hokkaido, and they affect flood control, fisheries in lake, and so forth. In this study, we aimed to reveal the developmental process of flood shoals by observations, which are current observation, water level observation, sediment survey, and video monitoring at the entrance of the Toufutsu Lake. Followings were major accomplishments of this study. (1) The current flow velocity during the flowing tide at St.400 was faster than that during the ebb-tide. (2) The relationship between current speed and friction velocity during the flowing tide is different from that during the flowing tide. (3) Flood shoals were developed by not only sea waves, but also adverse tide in the spring-tide.

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The characteristics of spatiotemporal variation of the multiple bar system on the Ishikawa Coast, Japan, have been investigated using a set of field surveys collected over 51 years. For the time variation, the behavior of sandbars is characterized by the presence of cyclic cross-shore migration of outer bars with approximately 10-year return period. Five cycles have been recognized from 1960 to 2010. The evolution of outermost bar strongly exhibits three-dimensional features. On the contrary to the bar migration patterns observed at many of other sites, the bar position are observed to move landward during the decaying phase.

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The shoreline changes of the Yotsukura and Natsui coasts facing the Pacific Ocean were investigated on the basis of the aerial photographs. In this area, beach changes had been triggered by the extension of the Yotsukura fishing port breakwaters. A wave-shelter zone was formed after the extension, resulting in sand deposition inside the port and erosion outside the port. Measured beach changes were reproduced using the contour-line-change model, and the topographic changes were predicted, taking the effect of the ground subsidence caused by the 2011 Great Earthquake into account.

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This study attempts to utilize the X-ray Fluorescence Analysis (XRF) in the coastal erosion/accretion survey. Sand samples are obtained on foreshore beaches (20 locations) along the Enshu-Nada Coast, from the inlet of Imagire to Cape of Irago. The XRF instrument can detect 23 chemical elements from a sand sample and 8 chemical elements of Sb, Sr, Rb, Fe, Mn, Ti and Ca are detected from all samples. In these elements, the content (ppm) of Fe is highest in all locations. The cluster analysis is demonstrated using these 8 elements and the result is compared with the data of beach width. The clusters of 20 locations by the analysis can be mostly explained by the present beach condition (wide/narrow) and the trend of beach erosion/accretion in recent years.

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Strong low-pressure systems traveled along Japanese Main Island in October 2006. High waves and storm surge attacked Kashima Coast resulting huge and historical erosion. This study analyzes sand loss and gain in sub-aerial zone of northern part, a stretch of approximately 38 km from Ooarai Port to Kashima Port, and of southern part, a stretch of approximately 15 km from Kashima Port to Tone River, using airborne laser data measured in October 2005, November 2006 and May 2011. Eroded volumes of sub-aerial zone from year 2005 to 2006 were estimated 620,000 m³ for the northern part, and 600,000 m³ for the southern part. Recovery from year 2006 to 2011 was prominent for the southern part which was 1,000,000 m³, whereas it was small for the northern part.

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Significant beach erosion has been developed on Nagayama-hama, Irabu Island, Okinawa Prefecture due to change of sediment movement by the construction of a bridge connecting the Irabu Island and the Miyako Island. This study aims at describing the erosion mechanisms on the basis of bathymetry measurements as well as numerical modeling of waves, currents and sediemnt movement. The performance of a sand-packed jetty tentatively introduced against beach erosion is also discussed by comparing beach topographies before and after the construction. It is found that the sand-packed jetty keeps its performance to reduce downdrift erosion although it tends to settle gradually owing to the local scour.

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The Dawu fishing port breakwater has been extended since 1956 in Taitung City on the east coast of Taiwan, obstructing southward longshore sand transport, resulting in sand deposition north of the fishing port and erosion south of it. As a countermeasure against the coastal erosion, beach nourishment using coarse material including gravels was planned, as well as the construction of groins on the downcoast. We analyzed beach changes around this fishing port using past aerial photographs and bathymetric survey data, and beach changes were reproduced using the contour-line-change model considering change in grain size. Then the effect of measures was investigated using the model.

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This paper presents results of a hydraulic experimental study on determination of optimum dimensions of the DRIM method, which is one of the newly developed measures against beach erosion problems. In the 2-D experiments onshore drift velocity and onshore sediment flux are measured for different cross-shore length of the DRIM by varying the number of rows of the DRIM blocks. Experimental results show no significant difference among the number of the blocks with respect to DRIM's capability of controlling onshore movement of sediment. A discussion is also made on the optimum pitch length of DRIM blocks versus the maximum orbital diameter of the bottom water particle.

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At Tottori Sand Dune Coast, the coastal erosion has been serious problems, and the beach nourishment project has been carried out for against erosions since 2005. However the effects of the project are not clarified and the detailed examination is not performed. The purpose of this study is to investigate the mechanism of the movement of the injected sand and the effect of the beach nourishment using the bottom sounding data at Tottori Sand Dune Coast and Tottori Port. The bottom sounding data were interpolated 20m, and the sand volume were estmated respectively. It was found that before the project, the sand volume were decreased, but after the beach nourishment project, sediment transport rate were toward to increased. This result shows that beach nourishment project are effective against beach erosions.

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The effect of the gravel nourishment at the Yamanishi area located in the western part of the Seisho coast, which was severely eroded by storm waves during T0709, was investigated. On the basis of the data, method to recovery of sandy beach by gravel nourishment was numerically investigated using the BG model. As the facility to prevent nouruishment gravel from being transported alongshore, two short groins with 50 m length were considered and 1.2 × 10⁵ m³ of gravel nouruishment was planned to recover sandy beach.

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On the Chigasaki-naka coast with 1.4 km length extending between Chigasaki fishing port and Chigasaki artificial headland, beach nourishment using coarse materials has been carried out since 2006. After the start of this beach nourishment, monitoring survey of changes in beach topography has been carried out to investigate beach changes and verify the effect of beach nourishment. In this study, various monitoring data such as the narrow-multi beam survey and photographs of the shoreline taken from a fixed position were analyzed. It was found that beach width of the coast was significantly widened by beach nourishment.

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The percolation effect of the foreshore composed of the combined layers of gravel and sand was investigated by a movable bed experiment using a wave tank. The grain size was selected to be d = 0.3, 1 and 3 mm. Under the condition that the grain size of upper layer is kept constant as d = 1 mm and the grain size of the lower layer is d = 0.3, 1 and 3 mm, berm height decreased with the coarser grain size, resulting in the reduction in wave run-up height due to the percolation effect. This implies that the formation of gravel layer of grain size larger than the ordinary gravel nourishment is effective.

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In Niigata West Coast, decrease of nourished sand due to sand drift along the scour formed behind the submerged breakwaters has been a technical problem. In order to prevent the sand loss, two countermeasures of sand control dike and submerged groin have been experimentally installed to prevent nourished sand from falling into the scour and running off from the nourished zone. Effectiveness of the countermeasures has been verified by successive observations of current and seabed height. As the results, it is confirmed that the submerged groin is effective in preventing sand loss and decreasing current speed near the seabed. It is also confirmed that the sand control dike has a certain level of effectiveness in preventing the sand from falling into the scour.

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This study investigates function of sand-filled-geotextile bag (sand pack), installed in front of sand dune, as decrement against beach erosion through laboratory experiments. And we investigate function of sand pack as decrement against beach erosion in three case of distance between shoreline and structure. We investigated a migration length of sand dune apex and area of cross section of sand dune. Sand pack was found to be effective to reduce beach erosion as compared with beach fill because sand pack worked as a retaining obstraction. And Experimental analysis revealed that sand pack is effective in decreasing amount of erosion as compared with artificial nourishment and breakwater.

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Factors of small erosion on the land side above the L. W. L. by the tsunami run-up were examined. About the tsunami run-up frequency, tsunamis that cause the topography change for the beach was four times. About the sediment grain diameter, the beach was covered with the coarse sand. Therefore, the ground-water rising with the infiltrating seawater was small. The berm erosion was not caused. About the subsidence, the subsidence due to the earthquake was 0.12m and the dune height was enough. The tsunami run-up did not exceed the dune top.

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Recently, some studies have found that the clayey sediments under strong waves show a remarkable reduction in water content. A lot of cracks have been observed in sediment surfaces during wave loading, and it has been reported that the water and fine particles were drained from the cracks. These phenomena may clarify the formation process of the ground and become a cause of siltation. In previous study, stability analysis of sediments has been proposed in 1999. In this method, dynamic shear strength which is reduced by 0.1~0.3 is used. But, this value is not defined specifically. So, in this study, yield stress is focused instead of dynamic shear strength. By using yield stress which is specifically defined values, the analysis results were able to evaluate the phenomenon.

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Recent beach changes of the Kohzu coast located close to a submarine canyon was reproduced using the BG model considering the grain size composition. Because of steep seabed slope of the coast, wave overtopping has been severe on the coast. Measures against wave overtopping were investigated by numerical simulation using CADMAS-SURF. Combined measure of gravel nourishment by the rate of 2 × 10⁴ m³/yr and raising the crown height of the seawall by 1.5 m along with the construction of parapet on top of the seawall was found to be effective.

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This study conducts two series of hydraulic experiment under some oblique incident wave conditions. One of the purposes of these experiments is to obtain the coefficient of equivalent crown height on Flaring Shaped Seawall. The other one is to clear the characteristic of wave overtopping at the joint section between Flaring Shaped Seawall and vertical one. The coefficient of equivalent crown height on Flaring Shaped Seawall shows different character under the oblique incident waves in comparison with conventional vertical seawalls. This study indicates that the value of Flaring Shaped Seawall could be taken as β=1.0 in the cases of longer incident wave period, such as T=1.6 sec. and 2.0 second. On the other hand, the coefficient tends to increase, β=1.15-1.3 with increase of incident wave angle under the shorter wave period. The increase of wave overtopping was observed at the joint section due to the run up of stem waves onto the wave dissipating blocks, though the wave dissipating works reduce the wave disturbance in front of the joint section.

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Experimental study is conducted in vertical 2-D wave basin to investigate the wave dissipation performance of floating breakwater under the influence of water level change. Two types of floating structure are tested; one is rectangular body and the other is double barrier floating breakwater (DBFB) which has vertical barriers on both sides of rectangular body. Fixed and heaving cases are examined to reveal the characteristics of reflection and transmission coefficient. From these results, it is found that fixed type breakwater is severely influenced from water level and DBFB shows high performance constantly.

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The recurved parapets in addition to revetments have the capability of reducible the volume of overtopping wave. But there are few research examples which gived quantification of the effect. Therefore, the purpose of this study is to acquire the underlying data for performing a suitable revetment design. That is to say, this study revealed the volume of overtopping wave which recurved parapets were made to change by the hydraulic model experiments on the assumption of steep slope conditions that the front geographical feature is one over ten and investigated the presumed method that is predicted wave overtopping quantity for various recurved parapets.

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To accurately measure wave-overtopping quantity by each wave in model experiments, so far we have developed a measurement technique using Particle Image Velocimetry(PIV) and confirmed its validity under simple regular wave conditions. In this study, a part of the calculation process used in the previous method was improved first. Next, for the purpose of understanding the applicability of the measurement method to irregular wave conditions, model experiments were conducted generating irregular waves and winds at the same time by using a two dimensional wind-wave flume. The experimental results clearly show that the individual wave-overtopping quantity in irregular waves can be appropriately estimated by using the proposed method.

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At Beppu port (Kitahama area 1), where Satohama creation is underway with considerations of protection for the high tide, utilization of the seashore, and the environment, a double parapet seawall for both utilization and protective effects was planned. For a double parapet seawall, vertical wave-dissipating blocks and a permeable layer structure for drainage were employed. To evaluate the multiple functions of protection for overtopping waves, CADMAS-SURF and a hydraulic model test were conducted. The calculated overtopping flow of CADMAS-SURF matched with that of the hydraulic model test, and therefore the applicability of the hydraulic model test was confirmed. Since the hydraulic model test is often performed for representative cross-sections, reflecting the results of the hydraulic model test for parameter adjustment in CADMAS-SURF resulted in improving the reliability of examinations of other parts of cross-sectional surfaces, and therefore enabled the omission of the hydraulic model test.

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In this study, CADMAS-SURF/3D(C-S/3D) using as intended to reproduce a more realistic flow conditions, we examined how to set the case to include in the model the turbulent diffusion and the influence of the pile. As a result, the application of the turbulence model is the use of logarithmic law as a boundary condition is valid. And by performing the model that considers three-dimensionality, to approach the experimental value due to the incidence of flow in the vertical direction was found. Numerical simulation was conducted using this result, many turbulent flows and vortexes has occurred around the pile and the opening between the body, and that has become a three-dimensional turbulence has been found.

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