The inclined wall suspension thermals are analyzed using OpenFOAM, which is one of the three-dimensional computational fluid daynamics tools. Dynamic SGS model is used for analyzing. The analysis model consists Finite Volume Method (FVM), TVD-superbee scheme and treatment of the particle deposition. The variations of the travel speed, the maximum height and amount of total suspended particles of a thermal are obtained from numerical results and compared with the experimental results. The agreement of numerical results and experimental ones is fairly well and it is found that this model can reproduce behavior of suspension thermals on inclined wall.

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 Hydraulic experiments and numerical simulations were carried out in order to analyze the influence of the planar shape of coastal sea area on sediment transport and bottom topography change due to tsunami. High velocity flow occurred due to the passage of tsunami through the abrupt expansion and a circulation flows took place in the rear area of the structure. The circulation flows generated behind the structure were found to be the same scale regardless of the length of the rear area. Therefore, deposit area with the same position and scale was formed even if the scale of the rear area was different. The numerical results also revealed that the introduction of the diffussion terms into the equations of fluid motion and suspended sediment are necessary to reproduce flow structure and topography change.

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 This study analyzed erosion of river mouth bars from Aomori to Chiba prefectures due to the 2011 off the Pacific Coast of Tohoku Earthquake Tsunami. The relationship between amount of erosion and tsunami overflow depth showed that river mouth bars were significantly eroded in the cases that tsunami over flow depth exceeds 2 m. Moreover, a numerical simulation considering sediment transport by tsunami was applied to the Abukuma river estuary and confirm its applicability. The results showed that variable saturation concentration as a function of tsunami flow regime gave more accurate topographic change than constant one.

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 This study investigated erosion mechanisms of coastal dunes through hydraulic model tests and numerical simulations. In the case of hydraulic model tests, the eroded portion of the dune depends on the regime of tsunami overflow. Seaward and landward slope was eroded by supercritical flow. In contrast, landward side was remarkably eroded by subcritical flow. In reproduction simulation of the hydraulic model test, eroded area was roughly matched by adjusting the parameters. Numerical simulation of topographic change of Nakatajima dune, which has a large crown width shows resistance to the erosion by tsunami overflow.

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 Because of the differences of wave energy fluxes over submerged breakwater and energy dissipation on a perched beach, the responses of perched beach under regular and irregular storm waves may give different results. To identify the differences, a series of experiments was conducted in a 2D wave flume under a pair of regular and irregular waves. The regular and irregular waves were set in equivalent wave height and wave energy. The maximum scour depth between initial beach profile and beach profile after storm and volume of sediment that was lost offshore over submerged breakwater i.e. volume loss are taken into account for evaluation. The results showed that under the equivalent wave height, the scour depth and volume loss of regular storm wave cases are much more than those of irregular wave cases. In addition, in all the cases of experiment, the perched beaches under regular waves showed eroded profiles, whereas under irregular waves they showed accreted profiles. Under the equivalent wave energy, the type and volume loss of perched beach profiles of regular and irregular waves are similar except for the scour depth. The classification of type of perched beach profiles under irregular waves is also discussed.

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 In this study, wave observation, currenet observation and bed level change observation were conducted around the Kuroiwa fishing port to reveal the channel sedimentation mechanism. From the results of bed level change observation, we find out that series of sand depressions and ascensions occurred for three times at the port entrance of Kuroiwa Fishing port during the observation. To reveal the process of channel sedimentation, we conducted wave-to-wave analysis, spectral analysis, EOF analysis, et al. From the results of these analyses, it is important to control sediment transport not only wind waves, but grouping waves attacked the Kuroiwa Fishing port.

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 Kanmon Route is a nallow channel with 50 km long, 500- 2200m wide, and 12 m in navigation depth, which links Japan sea with Seto island sea. In the channel, strong tidal current is generated by the difference of tide level of Hibiki nada sea and Suou nada sea. On the bottom of the channel, sand waves are formed everywhere and sometimes prevent vessels from safe navigation. This study intends to understand characteristics of sand wave evolution for efficient channel depth management. By analyzing bathymetry data frequently surveyed for monitoring of sallow area, the relation between depth change speed of sand wave crest and external conditions of water depth, tidal current velocity, and sediment properties.

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 A wide sandy beach with 130 m width extended in the 1960s in front of Oharai Aquarium located on the Oharai-isohama coast in Ibaraki Prefecture. Recently, the beach has been rapidly eroded with exposure of the seawall to waves. In October, 2015, caving of the seawall began, and the possibility of the failure of the seawall increased so that the seawall was forcibly broken down on November 18, 2015 to maintain the safty. In this study, the cause of the damage of the seawall was investigated, taking this seawall as an example. The long-term shoreline changes were investigated first using aerial photographs and satellite image of WorldView-2, and several field observations were carried out together with the investigation using aerial photographing by a Dorone.

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 Coastal sand transport often causes sand deposit on channels and basins at nearby ports and harbors, and hinders smooth fishery activities. This problem also occurs at Takasu Fishery Port (Fukui Prefecture, Japan), which locates at inner part of a bay. Therefore, it is necessary to investigate effective maintenance management method for the channels and basins of Takasu Fishery Port.
 In this study, calibrated a numerical simulation model of sand transport and deposit, which can take account of sand transport driven by long-period waves, and simulated a mechanism of sand deposit on channels and basins of the port. Secondly, we estimated amount of sand deposit during life cycles of the facilities for each method. Finally, calculated life cycle cost for each method by adding up expense of additional facilities and cost for dredging, and suggested most effective maintenance management method to sustain functionality of the channels and basins.

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 The response of the beach composed of the mixture of gravel and sand to waves was experimentally investigated using two-dimensional wave channel. Gravel of the median diameter of 7.0 mm and sand of the diameter of 0.3 mm were mixed, while changing their contents, and a model beach of the slope of 1/5 was produced using the mixed material. The experimental results were classified into two categories. In type A, shoreward sand transport was predominant, and gravel was deposited on the beach face. In type E, seaward sand transport developed, resulting in the erosion of the foreshore. These types were classified by the permeability k greater than 0.7 cm/s and smaller than 0.4 cm/s, respectively.

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 We investigated shoreline evolution from 1961 to 2013 on the Hasaki coast and found twice significant large scale shoreline advancement. The mean shoreline advancement for the period exceeded 70 m. The first large scale shoreline advancement from 1969 to 1984 was considered to be caused by an increase in the total sediment budget on the coast due to a sediment dump of 50 million cubic meters. The second large scale shoreline advancement was caused by landward cross-shore sediment transport after 1993. Artificial headlands, which were constructed almost the same period of remarkable shoreline advance around the southern part of the coast from 2002, also possibly contributed to trapping of longshore sediment transport.

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 The field experiments were conducted at Hasaki Coast, Japan to investigate the sediment cross-shore and vertical movements in the area of the swash zone to the offshore end of the surf zone using fluorescent sand. In the experiments, two diameters of fluorescent sand were installed in the coast for two locations in different colors, in the surf zone and the offshore end of the surf zone. After one storm pass through the site, nine vertical sand cores were collected. During the experiments, wave data and beach profile data were also observed. The cores subdivided after scanning by an X-ray scanner, and the vertical distributions of sediment diameter and the number of fluorescent sand were analyzed. When an offshore bar was not formed, fine sand located at the offshore side of the bar also contributes to the berm formation. The coarse sand located at the offshore side of the bar, however, does not contribute to the berm formation. The moving behavior of coarse sand was different from that of fine sand, and it was suggested that the coarse sand was immediately transported by near-bed motions of waves and currents during the storm.

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 A simple parametric model was developed for the systematic migration of sandbars on the Chirihama and Takamatsu Coast, Ishikawa, Japan. First, the principal modes of morphological variation was extracted by an EOF analysis for the annual surveys over 11 years. The cyclic migrations were well reproduced by the combination of the first and second eigen-modes, and the corresponding eigen-functions were examined in detail. The temporal eigen-functions for these modes were approximated by a sine and cosine function, respectively. The variations in phase and amplitude associated with the temporal eigen-functions were then expressed by linear regressions. The variations in phase and amplitude of spatial eigen-functions were approximated by exponential curves and the combination of linear and parabolic curves. The final expression was constructed by the combination of the approximated temporal and spatial eigen-functions. The approximated variations well reproduced the transition of the multiple sandbar systems.

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 A computational procedure for long-term beach profile change was proposed and incorporated into a three-dimensional coupled fluid-structure-sediment-seabed interaction model (FS3M), and numerical experiments on long-term surface profile change in a gravel beach were conducted using the improved FS3M to examine the sensitivity of the size of numerical cells and model parameters involving sediment transport. From numerical results, it was revealed that the final beach profile was sensitive to the size of the numerical cells, a wave update interval, and a reference height of the friction velocity. From the investigation of the beach profile evolution, it was found that the improved FS3M is expected to be a useful tool in assessing spatiotemporal surface profile change in a gravel beach.

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 Sediment transport mechanisms were investigated around the Hitotsuse River mouth located on the northern part of the Miyazaki Coast, where significant beach erosion is developed on the downdrift side of the jetty. Alongshore distribution of thermo-luminescence properties of feldspar grains sampled on the beach within 3 km from the river mouth demonstrated entrapment of sediments discharged from the Hitotsuse River on the north side while the sediment delivery to the south side was limited. Effects of noruishments were identified on the further south coast. Vertical distribution of sediment size and optically-stimulated-luminescence property indicated that the beach on the south side is eroding the past morphology created in the time scale of 10³ years.

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 Rapid erosion occurred on the Arai coast next to Imagireguchi Jetty of Lake Hamana in 2002. The cause of the beach erosion was investigated using bathymetric survey data. Beach erosion was triggered by the interruption of longshore sand transport to downcoast by the development of an ebb tidal delta associated with the construction of the jetty of Lake Hamana together with the attack of storm waves on the gradually eroded beach. Although the fact that downcoast erosion will occur when a sand spit develops was confirmed by the previous study, because of the interruption of longshore sand transport, it was found that the development of a submerged sand bar has a similar effect to the downcoast erosion.

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 A coastal area model with wave-current interaction was presented, and then the performance and applicability of the numerical to morphodynamics around river mouths due to waves, wave-induced currents and river flows were investigated. First, model tests were carried out under a wave and river discharge condition to investigate their capability of predicting the formation of sand spit and terrace topographies. Second, model verification using a field site was conducted and the applicability was investigated. From the computed results, it was confirmed that the prediction of presented model had good qualitative agreement with an actual sand spit formation.

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 Significant coastal erosion was developed on the Miyazaki Coast due to the partial disappearance of longshore bar. Laboratory experiments were conducted to investigate the relationship between the process of bar disappearance and the beach erosion. Analysis of high resolution nearshore topography data on the Miyazaki Coast suggested the disappearance of longshore bar would accelerate large scale beach erosion. Standard deviation of nearshore topography calculated in the longshore direction as well as two-dimensional wavelet analysis were found to be useful for the early detection of the bar disappearance.

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 Bathymetric survey data on the Hamamatsu-shinohara coast in Shizuoka Prefecture were analyzed to investigate beach changes after the beach nourishment using coarse materials including gravel. Owing to this beach nourishment, the foreshore width of the coast was extended, but the degradation of the offshore seabed still continues in the area deeper than -4 m, and a large-scale trough has been formed. The discharge of sand continues across the west end of the section at the beach nourishment area at a rate of 3.0×10⁵m³/yr by the westward longshore sand transport, even though sand supply from upcoast has exhausted. This rate is equivalent to the past longshore sand transport rate from the Tenryu River mouth before the various artificial alteration.

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 This paper describes the long-term shorelines variability of Cox's Bazar coast which is located south-east part of Bangladesh in terms of spatial and temporal over a period of 40 years. Recently the coast is experiencing severe erosion and it is becoming more vulnerable in some specific location. The spatial and temporal variability of the shorelines position is split by Empirical Orthogonal Functions (EOFs) decomposition. The result of EOF analysis shows the first five modes explains 86% of the variance and the recent erosion problem may have some relation with the variation around the Reju Khal area. The dominant modes of shoreline variability were correlated with the wave energy flux components estimated by MIKE21 SW model. The large variation around the Reju Khal may be due to longshore sediment movement, and the erosion problem at Marine Drive Road may have some connection with a growing spit.

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 River sand bar may become a barrier of smooth release of flood flow from the river channel into the sea until it is flushed. On the other hand, it prevents intrusion of sea water and transmission of high waves in to the channel. If flushing and recovery processes of the river sand bar are understood well, a sophisticated river management can be achieved. In this context, this study examines river sand bar flushing processes from eight years observation with X-band radar at the River Tenryu. 23 flushings of the river sand bar was analyzed and categorized into three patterns: (1) washed by the flood flow, (2) eroded by high waves, and (3) by the combination of flow and waves. The width of the river mouth before the flood is and important factor that determines the magnitude and pattern of the river sand bar flushing. Flushing and widening of the river mouth of 100 m or larger can be expected by flood of approximately 3 years return period. Further, the location of the river sand bar during the observation period was tracked: the mean location of the river sand bar migrated gradually and intermittently to the river side. During the migrations, erosion at the sea side of the river sand bar was observed frequently, while the area of itself increased slightly.

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 The morphological features of the cuspate foreland extended at the east end of Mikawa-oshima Island in Mikawa Bay were investigated by field observation together with the investigation of aerial photographs taken at eight times between 1977 and 2014. The change in shoreline configuration of the tip of Kohnose-bana cuspate foreland on the south shore on Sado Island was also studied, while referring to the study by Uda and Yamamoto (1990). On the basis of these field data, the BG model was used to predict the cyclic variation of the tip of the cuspate foreland responding to the change in wave direction.

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 The morphological characteristics of the cuspate forelands located in Gardiners Bay in Long Island and Ukraine Bay in Black Sea, and a land-tied island in Vietnam were investigated. The BG model was applied to the prediction of the development of a cuspate foreland, when an island is located offshore of the cuspate foreland and waves are incident from two opposite directions. It was found that a cuspate foreland elongates toward the lee of the island owing to the wave-sheltering effect of an island. The formation of a land-tied island when two sand sources are located on the opposite shores was also predicted using the BG model.

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 In recent years, a river mouth bar extended between Shimoda Port and the central jetty of the Shimanto River disappeared due to erosion at the Shimanto River mouth in Kochi Prefecture. After the disappearance of the river mouth bar, wave invasion into the river was enhanced and a sand bar in front of the left bank of the river, which was stable for a long time, was rapidly eroded, and sand was transported upstream, resulting in the formation of a slender sand spit. The formation of the sand spit was investigated by the shoreline analysis using satellite images together with the field observation. Moreover, the beach changes of the sand spit was numerically reproduced using the BG model.

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 The coastal sand dune and the pine forest in Rikuzentakata City mostly disappeared due to The 2011 Tohoku Earthquake Tsunami. However, the western part of dune, where the first coastal dike and the second landward dike partly remained, was prevented from flushing out. To reproduce the land remaining in numerical simurlation, the numerical experiments on sediment transport and tsunami inundation was perfomed. The simulation were performed under several condion of affected coastal dike and coastal forest. As a result, the coastal dikes had a large influence on the remaing area. Relatively the second coastal dike had a large influence. Additionally pine roots also prevent coastal dune from flushing out, though the effects had range. These results referred that coastal dikes partly affected by tsunami and tree roots itself mitigate the disaster damage.

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 On the Shonan coast, the reduction of a river mouth terrace offshore of the Sagami River and the shoreline recession downcoast of an artificial headland and Chigasaki fishing port breakwater have occurred owing to the imbalance in sand budget, causing several unsolved issues. In this study, these issues were studied, while refering the results of the the previous studies by the analysis of the shoreline changes on the basis of the aerial photographs and NMB data collected since 1999. The beach changes on the entire Shonan coast were triggered by the decrease in eastward longshore sand transport, even though beach nourishment has been carried out. Sand bypassing and recycle use of sand is required.

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 We examine oceanic dispersal of the iRIC-Nays2DH-evaluated sediment and suspended ¹³⁷Cs influxes from Niida River, Fukushima, with a particular attention to the first flood event in late May of 2011 after the Fukushima nuclear accident. Alongshore suspended ¹³⁷Cs transport occurs assymetrically, comprising storm-driven southward transport confined in the shallow area due to shoreward Ekman transport associated with strong northerly wind, followed by northwestward widespread transport under mild southerly wind condition. About 70 % of the Niida River-derived suspended ¹³⁷Cs remains near the mouth for 20 days after the flood event. Nevertheless, our model results as well as an observation suggest that the area is dominated by erosion as for high bed shear stress all the time, thus suspended radionuclides are redistributed to dissipate away in long term.

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 The natural environment of the Pacific coast of the Tohoku Region was largely affected by the Great East Japan Earthquake which occurred in 2011. Since then, the changes in the natural environment caused by natural recovery and alternation by human activities regarding the restoration and reconstruction projects are observed in the region. In this survey, the quantitative changes of shoreline and land cover (sandy beach, sand dune vegetation, coastal forest, others) of the hinterland from 1970s to 2014 were analyzed. The target area contains the sandy/muddy beaches of Aomori prefecture to Chiba prefecture (about 680km) which were affected by the 2011 Tohoku Tsunami. As a result, it was observed that the area of coastal forest decreased as the one of development land increased, and the area of sand dune vegetation decreased due to retreat of shoreline after the earthquake. Also, it was found that features of those changes differed depending on the coasts. In some coasts, the sand quickly returned to the beaches, whereas in some others, recoveries were not observed even at the sandbars of river mouth.

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 It has been five years since the occurrence of the 2011 Great East Japan Earthquake and Tsunami. The recovery of littoral system on Sendai Coast, Miyagi Prefecture is further investigated in this study. By adding two more years of shoreline position data extracted from aerial photographs and utilizing the Empirical Orthogonal Function (EOF) analysis, the recovery of littoral system of the coast can be revealed. Results indicate that the shoreline has not been in equilibrium condition yet. Shoreline positions at the severe damage areas, especially in front of the Gamo and Idoura Lagoons, are still advanced, however the shoreline position at the detached breakwaters is retreated. The first three components of EOF analysis are same with the ones of the period three years after the tsunami. However, the contribution rates have changed, increasing for the first component and decreasing for these other two components. Shoreline change rates along the coast of the period five years after the tsunami change significantly compared to the period before the tsunami, and comparatively change compared to the period three years after the tsunami. As a result, the sediment budget has been also changed.

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 Kujukuri Beach has been eroded owing to the rapid decrease in sand supply from the sea cliffs and the ground subsidence caused by the pumping-up of the ground water. In this study, the distribution of longshore sand transport in the entire area of the beach was calculated on the basis of the aerial photographs taken since 1947 and the bathymetric survey data, and the net distribution was calculated by removing the effect of the ground subsidence for the planning of measures against beach erosion. By separating the entire beach into three subareas (north, central and south Kujukuri Beach), the detailed beach erosion was investigated in each subarea.

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 A model for predicting long-term beach changes on entire Kujukuri Beach was developed using the contour-line change model considering ground subsidence. By separating four periods between 1947 and 2015, net longshore sand transport distribution was estimated in each period. The results of the calculation agreed with the measured, and the appropriateness of the model was confirmed. Finally, the shoreline change in 30 years from the present was predicted with/without ground subsidence, and the effect of the ground subsidence was evaluated.

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 This paper explores the way in which an extensive sedimentary prism has formed on a marine abrasion platform and farther offshore, through the fluvial supply since 1922 onward. The major aspects of discussion include the following: rates of beach progradation; seaward limit of crosshore profile change on a wave-dominated shoreface; and impact of major floods that brought large quantities of sand and mud into and beyond the surf zone. The examination of sediment cores by X-ray computerized tomography (CT) clearly shows that the sandy deposits on the shoreface are intercalated with a series of muddy flood layers. Furthermore, the identification of freshwater diatom assemblies in columns of sediment retrieved from greater water depths (30 - 60 meters) enables the authors to estimate the rates of sediment accumulation on the inner shelf in the recent nearly 100 years.

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 A narrow multi-beam suruvey was carried out offshore of the Seisho coast in Kanagawa Prefecture to investigate the offshore seabed topography. Three extremely steep seabed slopes were discovered in the submarine canyon offshore of the Morito River mouth with a slope angle ranging between 66° and 77°, which has a high possibility of the slope failure during an earthquake. Moreover, a streak pattern was found on the steep slope at the east end of the submarine canyon. This was assumed to be formed by the discharge of sand supplied by the eastward longshore sand transport. Similarly, another streak pattern was found at the west end of the submarine canyon which was assumed to be formed by the discharge of sand supplied by westward longshore sand transport.

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 Amounts of sediment yield, sediment deposits in dam reservoirs, and sediment digging in rivers and the sea were analyzed, as well as river channel change, relative sea level rise, and beach width change from around 1950 to 1990 in Japan, to quantitatively clarify the effect of sediment balance in catchments from mountains, rivers, to the sea. The approximate total amount of the sediment yield is 5,600 million m³, sediment deposits 800 million m³, and river digging 1,600 million m³ in the period, respectively, and more than half of the sediment yield is estimated to be potential sediment supply from rivers to the sea. On the other hand, the approximate total amount of sand loss in the sea is 2,000 million m³ and sea digging 700 million m³, respectively. All these data used in this study cannot fully explain the sediment balance in the catchments; however, they revealed that the river digging could be one of the major factors which affected the beach erosion in the period.

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 The contour-line change model considering change in grain size was used to reproduce the beach changes until 2015 on the Shizuoka-Shimizu coast. In the calculation, the effects that the grain size of the beach nourishment material prepared from the Abe River bed was excessively coarser than that naturally supplied from the river mouth, and the detached breakwaters offshore of Zo-Hebizuka area blocked longshore sand movement were taken into account. In order to recover sandy beach rapidly, it was concluded that sand bypassing at a rate of 8×10⁴ m³/yr from the Abe Riber to the coast, sand back pass from the Miho runway to the Shimizu coast at a rate of 5×10⁴ m³/yr are required together with the increase in sand volume from 3×10⁴ m³/yr to 5×10⁴ m³/yr instead of the beach nourishment of 2×10⁴ m³/yr at Zo-Hebizuka area.

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 Beach changes when groins with various shapes were installed on a dynamically equilibrium coast with a constant rate of longshore sand transport were investigated using the contour-line change model. First, the Numakawa-daini floodway on the Fuji coast was taken as an example of the beach changes around a groin installed on a steep coast, and beach changes were reproduced using the contour-line change model. Then, the relationship among the length of the groin, its point depth and longshore sand transport was investigated together with the study on the difference between L-shape groin and a single groin. Moreover, the difference in the function of a single groin and L-shape groin to be installed on the Shimizu coast was studied by the same model.

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 The recovery method of sandy beach in front of the seawall against tsunami on the Sagara-suzuki coast was investigated using the contour-line change model considering change in grain size of sand. The beach changes between 1977 and 2014 were reproduced first to confirm the effect of the model, and then future beach changes were predicted. As a result, the best way to recover sandy beach with a 30 m width, which is required for the protection against waves, was such that nine groins with a crown height of 2 m above MSL are installed at intervals of 350-400 m north of Jitogata fishing port together with the beach nourishment of 8.0×10⁵ m³ using fine sand of grain size 0.2 mm.

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 Coral cays formation mechanism has various field surveys, experiment, and numerical simulations. The characteristic feature was made clear gradually. In these researches, sufficient amount of coral gravel are transported and can make island under certain condition (wave height, wave period, water level). However, the condition in the real coral reef does not necessarily correspond to the experiment condition. In this research, we studied the form of offshore structure which can advance formation of coral cays by movable bed experiment. We got the some results that permeable structure is more effective than impermeable structure, that the form of structure can change the efficiency of sedimentation and sea-bottom slope under the condition that permeable structure's height was under water level, and that the structure which has tetrapod (like a coastal structure) was efficient. In addition, we conducted numerical simulation about wave and change of seabed topography, and the results corresponded to experiment data with considerable accuracy.

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 Ibusuki coast has been the most popular spot for the sand steamed hot spring. In addition, its sandy beach has important functions in the environment and disaster prevention. However, the loss of its functions has been threatened by the recent coastal erosion. Integrated shore protection system composed of beach nourishment, groin and distorted ripple mat (DRIM) has been applied to prevent the nourished sand from being washed away. The beach nourishment was constructed in 2009 and 2011 with topographic monitoring surveys. The present study discusses the effects of the countermeasure work comprised of DRIM and groin based on the survey results from 2010 to 2015. Evaluation of the beach deformation was carried out through topographic change, deformation trend and empirical eigenfunction analysis. From the results of the evaluation, it was confirmed that the countermeasure work is effective in retaining the nourishied sand.

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 In this paper, a new method of beach nourishment, in which sediment dredged from a longshore bar is filled at the shoreface, was proposed as one of the measures for beaches that suffer from chronic beach erosion after a storm. Laboratory experiments showed that the proposed method effectively accelerates the recovery of the shoreline and formation of the berm. Among the parameters that may influence the effectiveness of the method, a volume of nourishment, characteristics of the recovery waves, and water level were important. The location of deposition was not very sensitive.

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 Although the Katayamazu area in the south end of the Ishikawa Coast is located downstream of a longshore drift, its beach erosion is very intense and has frequently broken the coastal revetments. Therefore, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) designated the area as its direct control area from June 2006. As the area located in the Etizen Kagakaigan quasi-national park and its offshore is a good fishing place and fixed netting fishery has vigorously grown, it is indispensable to consider its landscape and fishery when developing its beach erosion control works. This study determined the mechanisms of sediment transport in the area by constructing an artificial beach nourishment for test and implementing the monitoring field surveys of it. The study results will be used to develop beach nourishment works without longshore drift control in the area.

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 Climate change impact due to global warming on beach profile is projected based on the global climate projections. Changes in the coastal external force due to climate change are not only sea level rise, but changes in the wave characteristics such as wave height, period, and wave direction are also considered to beach profile changes. Kaike coast in Japan is surrounded by Shimane Peninsula. By the distinctive terrain facing the Miho Bay, changes of wave characteristics at the Sea of Japan is considered to check the sensitivity on the beach terrain. In this study, the bathymetry changes of Kaike coast protected by existing artificial reefs and sand recycling are simulated forced by future climate conditions and it is revealed that wave climate gives significant impact on the bathymetry.

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 We conducted nearshore topography monitoring by using ARGUS cameras and UAV on Fukude-Aasaba Coast, Shizuoka Prefecture on the Pacific coast of Central Japan, where an experimental sand-bypassing system with jet-pumps has been introduced. Monitoring of shoreline change by ARGUS cameras demonstrated that beach erosion occured by several storms in winter. The UAV-based topography monitoring system consisted of land topography measurement by SfM technique and bathymetry estimation based on the tracking of wave crest lines. Significant deposition was found around the outlet of the sand-bypassing system.

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 We developed a nearshore topography monitoring system using ARGUS cameras and UAV on Yotsugoya Coast, Niigata Prefecture, where multiple sand bars were developed. Sand-packed groins were introduced with nourishment as countermeasures against beach erosion. We developed a new technique to estimate nearshore topography by extracting wave crest lines from pictures taken by UAV. The deformation of multiple sand bars were investigated by using time-averaged pictures taken by ARGUS cameras and UAV. Movement of sand bars in half a year was compared with survey data.

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 Armor blocks and wave dissipating blocks have been used very often for the purpose of coastal protection in Japan. Therefore, if there is an armor block which can be expected on wave-dissipating and flow velocity reduction effect, it is possible to contribute to coastal protection, construction cost reduction and resource saving. To evaluate and understand these performance of armor blocks, it is important to elucidate the impact of the hole shape of armor block on the flow regime. In order to investigate the efficiency of the blocks, the series of hydraulic experiment was carried out. It revealed the characteristic of stream regime by the difference in porosity shape at flow by using PIV. In the result, it was found that the stream regime inside the porosity differs for the square, round and hexagonal shape hall. It was also found that turbulent intensity differs for the velocity which flows in the porosity and the length of the leg.

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 Laboratory experiments were performed to study wave transmission and reflection capacity by pervious structures as coastal protection from waves. The energy dissipated in pervious structures may be evaluated by using the drag forces acting on the pervious structures and particle velocities of principal waves in pervious structures. A theoretical analysis based on application of the continuity and energy equations to the flow through the pervious structures were made to evaluate wave transmission and wave reflection capacity of structures. The transmission coefficient K_t and reflection coefficient K_r of (a) Wave dissipating caisson with circular cylinders in front of wall and (b) Blocks of detached breakwater were also studied experimentally and theoretically.

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 In the previous studies on low reflective seawalls comprised of curtain walls and a rear-side vertical wall, it was presumed that an upper side of the water chamber of the seawall was open to the atmosphere. Therefore, there is no restriction on the behavior of pumping mode wave motions in the water chambers and consequently significant wave energy dissipation due to such wave motions is active. However, in the real site of wharves and piers, the upper part of low reflective seawalls is generally capped by ceiling slabs to be able to use the space for loading and unloading cargos to boats and ships. Under such general situations, it may be necessary to keep air ventilations above the water chamber to be able to activate pumping mode wave motions and consequently to dissipate reflected waves from the pier. In this study, we have proposed a method to set vertical slots on curtain walls for the ventilation. Effectiveness of such vertical slots on the curtain walls has been examined experimentally and theoretically. Additional examinations have also been carried out to study the size of vertical slot on the wave dissipation effect.

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 This paper presents an experimental investigation to the hydrodynamic characteristics of pile-supported cylindrical oscillating water column (OWC) device as offshore breakwaters. The relation between wave control effects and wave energy conversion efficiency of OWC device was experimentally investigated. The effects of relative diameter, draught, opening in the top cover and gap between the OWC device and the side wall on wave reflection, transmission, energy dissipation, the oscillating water amplitude and pressure fluctuation inside the OWC chamber were examined. It has been found that high-speed air flow through a small opening (orifice) extracts energy from the wave field and reduces both the wave reflection and transmission coefficients. Except for long-period waves, energy dissipation contributed from vortex shedding at skirt edges of OWC and from air-flow through the orifice device is essentially equivalent. The orifice with a very small opening achieves the smallest transmission coefficients. Although the maximum primary wave energy conversion efficiency could be achieved for longer incident waves, both the low transmission coefficients and the relatively high wave energy conversion efficiency could be performed for intermediate range of wave periods.

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 A new single layer breakwater armour unit has been developed by Samsung C&T Corp., Chisui Corp., et al over the past two years. This development has been empirically tested and verified by running a drop test, as well as performing structural analysis and physical model tests. The structural and hydraulic stability has also been thoroughly verified. In addition, favourable results in terms of economics, environment and constructability have been gathered. Given this excellence, this new single layer armour unit is expected to be used for overseas bidding projects and execution sites around the world including Japan.

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 A submerged mound type long-period wave absorbing structure is one of the promising countermeasures to problems in cargo handling. This study investigates the wave-absorbing mechanism of the structure. Theoretical analysis on the wave reflection focused on the effect of the phase interference and numerical analysis using the VOF method on the energy dissipation due to the mound were conducted. Theoretical analysis indicated that a low reflection from the mound slope due to the low crest elevation results in a low reflection coefficient as a whole structure. In addition, it is indicated that the short wave-length within the mound leads to high phase interference effect. As another approach, energy dissipation due to the fluid resistance of the mound was directly analyzed by means of the VOF method. The analysis clarified that the submerged mound effectively dissipates wave energy over a wide area of the crown section by concentrating the flow into the crown section.

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