In this study, we determined how visitors feel coastal landscape by sensible elements with results from conjoint analysis evaluation which we have been done from 2011 and continuous evaluation by TCM for a coastal improvement project. By calculation of project value by TCM, we found that project value increases in case there is an effect of landscape improvement by new spatial expanding. On the other hand, project value remains constant in case there aren't any new improvements. Our results also shows satisfactory degree of users on social capital improvement is clearly related to enhancing degree of improvement. The result of calculation by conjoint analysis shows WTP increases by improvement of height of coastal protection facilities.

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 After remote islands development for a long period and enactment of Basic Act on Ocean Policy, various actions to remote islands near the border are expected and excuted. For better social and environmental understanding of remote islands, a new index on networks of remote islands is introduced by analogy with graph theory. It is composed of three parameters such as number of ports, courses and services. The investigations on typical remote islands in the ocean of Kagoshima, Nagasaki, Okinawa prefecture and Tokyo showed the effectiveness of the proposed index.

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 Most of the maritime disasters are caused by the immature technology, and insufficient knowledge of navigation. Especially, a ship encounters to many dangerous situation in importing and outporting. For the reduction of marine disaster, many appropriate navigational information are demended for a navigating officer.
 The present paper proposes the effective presentation for information of navigation using GIS and the efficiency of navigation simulation supporting safety navigation is examined for prevention of a marine disaster. In this study, authors discussed two method of supplying navigational information. The first method is by supplying the 3D model into GIS. The second one is embedding 360° panorama picture into GIS and a navigating officer can check the 360° view around before departure. It was comfimed that these proposed methods were very effective.

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 In recent years, a lot of goods or materials move globally in tandem with the rapid development of the global economy. The vessels which assume the mass transportation of these goods are getting larger, and the number of them also grows. the maritime transportation will be rapidly developed in future. As a result, the increasing number of vessels result in an increase in the number of marine disaster. In addition, many vessels in a port are crowded and lie at anchor to wait for loading outside of a port. As results, economic loss of fuel and global environmental preservation issues, including atmospheric emissions from ships (including carbon dioxide and nitrogen oxides) occurs.
 For resolving these problems, it is necessary to examine the actual traffic situations of sailing vessels. This paper deal with the examination of maritime transport using AIS data in Osaka Bay.

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 The many maritime laws are provided for safe navigation in marine traffic. As the coastal area such as Tokyo Bay, Ise Bay, Osaka Bay and Setonaikai is very confused by many sailing ships and have shallow water area, the risk of the generation of a marine disaster is very high. Especially, the most dangerous become high in the case of inport and outport of a special port. The regulation rools for a siling ship passing a special port are provided for safe navigation.
 The object of present paper is the examination on routs keeping of a ship sailing proposes under maritime low in inport and outport.We could obtain many information for the object that guidance for keep of maritime regulation or arrangement of maritime law will be proposed in future.

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 The size of container ships and bulk carriers have been getting larger and larger. Enlargement of ship size brings about reduction in the shipping cost. However, at the same time, it requires development of port facilities. Above all, the dredging of fairway is needed and that requires a lot of expense. In fairway planning for new-comer ship, it is necessary to reproduce the maneuvering motion of design ship and to consider various elements including weather and sea conditions around fairway. Based on this background, this study enabled the fairway planning for mega container ship and bulk carrier.

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 MLIT (Ministry of Land, Infrastructure, Transport and Tourism) has been continuing the yearly survey of bathymetry in Kanmon waterway since 1974, and conducting dredging to maintain the waterway. The sounding data is exceedingly valuable; especially the data obtained with a new surveying ship launched in 1995 is more accurate than before.
 In this study, for the purpose of clarifying the characteristics of the depth changes in Kanmon waterway, the sounding data obtained with the new surveying ship was analyzed in detail. First, yearly water depth distributions were analyzed by using a GIS. Then, taking account of the depth change by dredging, the depth change rates at all survey points were calculated by the regression analysis. Sea areas, where the depth change rates show a clear trend, were picked up by using several functions of the GIS, and the characteristics of depth changes in the waterway were discussed.
 The main conclusions are as follows;
 (1) The water depth changes are remarkable in Nantosuido area and Mutsurejimanishigawa area, and at some places in Hayatomoseto area.
 (2) It was found that the water depth change rates in Nantosuido area greatly increased after dredging.

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 It is desirable to establish the estimation of the wave height of the long-period waves at any location along the Japanese coasts. As a basic study for the estimation, the correlation between the long-period waves and the significant waves was investigated. A large number of observed wave data of a duration of 4 years at 47 locations along the Japanese coasts were used for the regression analysis. The wave heights of the long-period waves estimated by a quadratic regression expression provided better results compared with those estimated by a linear regression expression. The regression coefficients at all the 47 locations were determined. The regression coefficients among most of the locations were also determined. It was found from the estimation of the long-period waves using the significant waves that it was difficult to apply the regression expression with the coefficients among most of the locations. The estimation using the regression coefficient derived from each location was in good agreement with the observed wave heights of the long-period waves.
 In addition, the parameter s was introduced as the deviation of the significant waves. As a result of the comparison of s value between the different locations, the parameter s can evaluate for the applicability of the estimation for the wave heights of the long-period waves by the regression expression.

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 Directional wave spectra and directional spreading parameter are estimated to investigate properties of wind waves observed in the Sea of Japan in winter season. We estimated directional wave spectra using an estimation method of NIDE proposed by Izumiya et al. The NIDE enabled us to produce high directional resolution even under the different climate condition. The value of directional spreading parameter s observed in the Sea of Japan decrease rapidly as the value of deepwater wave steepness larger than 0. 04 increases. It is also found that the value of s decreases as the wave height increases larger than 4m.

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 In this paper, we investigated the characteristics of bound waves simulated on the basis of weakly nonlinear directional wave theory. Although bound waves develop when significant wave heights are large, they are small through the year and observed infragravity waves almost consist of free waves. The ratio of bound wave height for ingragravity wave height is large when water depth is small. And it is also large when S_max is small in The Sea of Japan. We proposed a formula for estimating the wave height of bound wave considering S_max and showed its validity.

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 In order to examine characteristics of secondary undulation in Urauchi Bay of Kamikoshiki Island, direct measurements of sea level, current velocity and atomospheric pressure were made during February 10 - March 31 in 2012. It was found from the observational results that the first-mode oscillation with the 23.8-minute period and the second-mode oscillation with the 12.5-minute period were dominant in the bay. Moreover, it was clarified that the ratio of the amplitude of the first-mode oscillation at the mouth of the bay to that at the Oshima fishing port is 1:8.7 on average, while the ratio of the amplitude of second-mode oscillation at the mouth of the bay to that at the Oshima fishing port is 1 : 8.9 on average. The occurrence of the large secondary undulation in Urauchi Bay depends mainly on the the second-mode oscillation with the 12.5-minute period.

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 In many ports, it has been reported that long-period waves cause trouble in cargo handling. As a countermeasure to this, a slightly submerged mound type long-period wave absorbing structure installed on the harbor side of the breakwater is proposed. Because the structure is to be situated behind the outer breakwater which faces the open sea, severe wave overtopping will inevitably be encountered. To realize such a structure, the armor units must have sufficient stability to overcome wave overtopping. However, the design method has not been established yet. Therefore stability tests on the armor units against wave overtopping from the sea side were conducted aiming at a design formula for armor units.
 In this paper, it became clear that the deformation type of the long-period wave absorbing structure were different depending on the width of the structure. A prediction formula for the stability number for Tetrapods for each cross section condition used in the Hudson formula was proposed by modifying the existing empirical formula for the sea side Tetrapods on a horizontally composite breakwater. Its validity was confirmed. As a result, the required mass of Tetrapods for the proposed submerged structure can be calculated properly.

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 A breakwater with retreated parapet is sometimes employed in order to reduce horizontal wave force and wave overtopping. This study proposes a new retreated parapet that has a flared cross section. The parapet has a deep circular cross section which overturns an incoming flow motion to offshore. The effect of this flared parapet on reducing wave overtopping was investigated through hydraulic experiments. The experiment was carried out with two dimensional wave tank. Numerical simulation with using Cadmas-surf was also conducted to investigate the characteristics of hydraulic pressures and foeces on the parapet. This study clears that the retreated parapet with flared cross section reduces the wave overtopping more effectively than a upright parapet which is conventionally employed on coastal structures. The flared parapet on the rear side has smaller horizontal force than that on the front side. Furthermore, the downward force acts on the flared parapet, and the force becomes larger when the paraper retreats to the rear side.

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 Several small rivers flow into the Shizuoka coast facing Suruga Bay. At the mouth of these rivers, northward longshore sand transport prevails and coarse material was deposited at the river mouth, resulting in the river mouth closure. In this study, a dynamic equilibrium condition, in which 1.7×10⁵m³/yr of longshore sand transport can continuously develop along the coastline, was produced in the model, and various countermeasures against the river mouth closure were investigated by using the BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept).

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 In a harbor tranquility analysis, transmitted waves sometimes should be considered to estimate a cargo handling operation rate in a berth because wave overtopping is usually permitted in the design of breakwaters. A Boussinesq model equipped a calculation technique of wave overtopping can be expanded to calculation for generation and propagation of transmitted waves in a harbor inside with a flooding calculation technique on the top of breakwater. By using this expanded model, transmitted waves observed at several station in Kanazawa port are reproduced and accuracy of these calculations would be verified. These results indicate that high-frequency waves from 0.2 to 0.4 Hz are generated by inflow of wave overtopping volume behind of the breakwater.

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 A coastal railway has a risk that traffic hindrance occurs for high waves. Storm waves were reproduced in hydraulic model tests. Wave overtopping characteristics were examined by 1/40 model tests in a wave channel. The pattern of ballast movement with different wave conditions was analyzed by 1/4 model tests in a channel. Based on the test results, the calculation formula for spray of wave overtopping was proposed, and the effect of wave splash barrier on ballast damage was also clarified.

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 The Kuji harbor was severely damaged due to tsunami with soliton fission caused by the Great East Japan Earthquake on the 11^th March 2011. The characteristics of tsunami with soliton fissions in a harbor are not well known owing to the lack of detail investigations although they were observed in the 1983 Nihonkai-Chubu Earthquake Tsunami and the 2004 Indian Ocean Tsunami.
 In this study, the model experiments and numerical simulations with Boussinesq-type wave transformations model are conducted to investigate the characteristics of tsunami with soliton fission in Kuji harbor. The soliton fission criteria are dependent on the period and height of the tsunami body and the local bottom bathymetry, and it is possible to evaluate the propagation of tsunami with soliton fissions by using the numerical simulations.

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 A two-dimensional run-up and inundation model based on a CIP method was modified in this study so as to satisfy the continuity equation with reasonable accuracy. Numerical simulations on tsunami bore were carried out in order to validate the model and discuss the effects of wet-dry condition and overflow condition on the calculation accuracy. As a result, the model was confirmed to be able to represent closely actual water surface profile by using the slip condition on the wet-dry condition. Furthermore, the numerical results without the overflow formula were found to be in good agreement with the experimental ones.

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 When tunami analysis is conducted, some probrems occuer according to open boundary with wave dumping layer. Reflected waves from open boundary or wave dumping layer effected to the analysed results. We studied these probrems by easy theoretical approach. We found wave number modulation occuer in wave damping layer and Sommerfeld's open boundary condition can not be satisfied. Moreover we note that wave reflection also generated in wave dumping layer. We confirm these two generation system of reflected waves by model equation analysis. After comparison numerical simulation and theoretical approach, waves reflected in the wave dumping layer in this study condition. We pointout that wave dumping layer should not be use in long wave nanalysis include tunami analysis.

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 The 2011 Tohoku earthquake tsunami devastated the coastal zone in east Japan. It was also reached to the Pacific coast in west Japan area. The most reports were limited reaching tsunami time and its height. However, it is important to consider the effect on water mass structure by tsunami waves from the viewpoint of sustainable fisheries industry or conservation of marine ecosystem.
 In this study, from the analysis for monitoring data in Shikoku and Seto Inland sea, temporal breaking the stratification by tsunami waves and the appearance of high-frequency component were confirmed.

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 Ocean currents and densities in Miyako Bay under various meteorological conditions were reproduced using an ocean current model, CCM, to examine characteristics of the current and density structures. Calculations using topographic data obtained before and after the tsunami were also conducted to evaluate the influence of topographic changes on the current and density structures. Results show that the inflow rates from two rivers strongly influenced the sea surface density distributions. Moreover, results show that topographic changes caused by the tsunami locally influenced the sea surface density and the direction of the currents.

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 In this study, we simulate a overflowing situation around a breakwater with MPS method, one of particle methods, and CADMAS-SURF (CS2D), and compare the calculation results for understanding characteristics of both methods as a basic study of a method that can analyze events for a tsunami-resistant breakwater design. In addition, a case of impermeability mound and two cases of impermeability and permeability mounds are calculated by MPS and CS2D method respectively.
 The mean velocity behind the breakwater shows a vertical distribution in both CS2D and MPS method, that is, there is a similar tendency between them, when the mound is impermeable. However, the velocity is maximum around the bottom of the mound in CS2D with impermeability. It is identified that the size of overflow depth makes a difference in the calculation accuracy, in each methods, for the maximum wave pressure which acts on the front of a breakwater. The MPS method adjusts the spatial waveform around the breakwater at the time of overflowing to the past previous results from CS2D.

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 Recently, when earthquake occurs, damage to container due to fluid motion in the container has been discovered and reported. Under this type of condition fluid surface in the container oscillates greatly and the motion of fluid becomes a three-dimensional complex flow with a breaking wave. Therefore, the necessity to develop a three-dimensional numerical simulation method for solving nonlinear hydraulics phenomena is very important.This paper shows the changes of vortex strength using a three-dimensional particle method subject to the oscillation fluid in a cylindrical container, and comparing with the experimental results the relation between vortex strength and fluid motion pattern is discovered and characterized. In addition, this study shows the transaction of motion pattern depending on depth radius ratio through to the relation between vibration frequency and depth radius ratio.

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 Adoption of Hermite element with complete cubic polynomials is one of the choices to apply the CIP scheme to unstructured triangular meshes. This would be expected to be an effective method to solve advection problems in complicated boundary with high accuracy. In this study, characteristic of numerical error of advection calculation with Hermite triangular element was compared with that of A-type CIP scheme by numerical experiments and Von Neumann stability analysis. Dependence of numerical error of the Hermite triangular element on the flow directions was revealed.

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 In this study, we examined the validity of numerical computation by applying two different assumptions, hydrostatic and non-hydrostatic assumptions, with the change in mesh aspect ratio. Tokyo Bay was chosen as an example of an enclosed bay in order to investigate internal wave breaking over a slope. We applied 6 different mesh aspect ratios, 5, 10, 25, 50, 100 and 500. As a result, it is found from non-hydrostatic computations that the larger the aspect is, the larger the numerical error appears. In contrast to the non-hydrostatic computations, the numerical error is found to be the same in the all mesh aspect ratios. Additionally, it is revealed that mesh aspect ratio should be less than 10 in non-hydrostatic computations.

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 In this study, the numerical simulations on two-dimensional dam break and three-dimensional collision between bore and a structure were conducted using OpenFOAM, which is one of the three-dimensional computational fluid dynamics tools. The validity of OpenFOAM was verified by comparing the numerical and experimental results. Furthermore, the validity of free surface analysis method based on the VOF method was examined in terms of the dynamic behavior of free surface. The numerical results revealed that OpenFOAM has good calculation accuracy for some hydraulic phenomena related to coastal and ocean engineering. It was also found that the parameter c_α, which indicates the control parameter on numerical diffusion, influences the dynamic behavior of free surface when the flow field largely changes.

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 We present a new faster GPU computation and algorithm for CADMAS-SURF/3D by a CUDA parallelization techinique on a GPU accelerator "Tesla". In this paper, we examine the CUDA porting tool for GPU computation and suggest a macro code by C preprocessor for CADMAS-SURF/3D originally coded in FORTRAN to be adopted into CUDA C language. Furthermore, we optimize the data access sequence pattern from a profiling result to eliminate the calculation bottleneck. We inspect the legitimacy of the solution by examining the rounding error, and then examine the program tuning by a data sequence access pattern optimization.

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 Field investuigation was carried out on the Hokota coast in Ibaraki Prefecture to investigate seasonal beach changes around the artificial headlands. As a result, the beach materials of the Hokota coast was composed of fine and medium-sized sand with the content of 90 % by two grain sizes, and medium-sized sand was mainly deposited in the zone shallower than 3 m depth. On the immediately north side of artificial headland No. 23 located on the south side, the amount of medium-sized sand increases in summer compared with that in winter, wheras vice versa near the south side of headland No. 29. This phenomenon was explained by the fact that fine sand is transported by northward long-shore sand transport in summer and vice versa in winter. This was also confirmed by the field observation of shoreline changes using UAV.

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 The coast located in the west of Gono River in Shimane prefecture is divided into three sandy beaches by the small headlands. It is obvious by the shoreline change analysis using aerial-photographs that the erosion begun from Gono river-mouth in 1970 has been spread westward and reached in Wakihashi coast over Mashima headland. Contrarily in the west of Wakihashi coast and the west coast over Ohsaki-hana headland, the shoreline has been advanced. These shoreline changes from 1988 to 2010 were simulated by the shoreline model under the wave condition due to the wave transformation analysis based on the wave observation data in Hamada harbor. The simulated results show that the westward longshore sediment transport has been dominant and the sediment transport rate over the headlands could be estimated. Thus, it is necessary to control the westward longshore transport rate to prevent the erosion from a viewpoint of the existence of the sand transport rate over the headlands.

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 Field observation was carried out to investigate beach erosion in Blue Bay area in Mauritius. The effectiveness of a method combined with a satellite image, in which field observation points are accurately shown, and field photographs with a scale such as a measuring stick was shown. In this area, severe beach erosion occurred in the past, but the exact cause was not clear. The cause was such that the longshore movement of sand supplied from the reef edge was obstructed by the construction of groins.

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 The influences of climate change due to global warming have been estimated on wave characteristics such as wave height. The effect may occurred on not only wave height but also wave period or wave direction. Because those wave parameters of a specific coast could be changed due to the sea area and geological characteristics, it is important to the climate change effcts on wave climate in order to understand the effect on shoreline change in a long term.
 In this study, shoreline change model is developed, which has been calibrated by using local survey and aerial photos. And future wave conditions, based on future climate which has different SST for the end of this century, are estimated and the effect on shoreline change is estimated based on the wave climated change.

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 Sand samples were collected in selected 18 beaches and in rivers which are supposed to supply sand to the beaches in order to examine supply sources of sand of the beaches in the Awaji Island. Sand colors were analyzed using the simple color analyzing method proposed in our preceding papers and relationships between sand colors and geological features of drainage areas of the rivers were investigated. Color differences of the sands collected in the rivers were relatively obvious owing to distinctive colors of geological stratums of the Awaji Island. Those of the beach sands were unclear because of weathering, artificial nourishment or sand transport by coastal current.

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 In the planning of the construction of a road and parking space near the shoreline, such facilities are often planned to be built on a natural beach, resulting in the artificial narrowness of the natural beach. In this study, the example of the Toyo-oka coast located in the south part of Boso Peninsula, Chiba Prefecture, was investigated. A fishing port breakwater was extended on this beach, resulting in the expansion of a wave-shelter zone to the adjacent natural beach. Then, longshore sand transport toward the waveshelter zone was induced, and a seawall along with large concrete armor units as a protection of the seawall was built on the past shoreline. Finally a high seawall killed the scenic beauty of the sandy beach.

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 Several measures against the closure of the opening of the floodgate of the Fujihaya River were investigated. Because 1.0×10⁵m³/yr of eastward longshore sand transport prevails near the floodgate, several methods were proposed while maintaining this longshore sand transport. The long-term shoreline changes were investigated using aerial photographs, and then dynamically equilibrium beach was produced in the model using the contour-line-change model, and the effect of the measures was predicted. Finally, we proposed a method in which wave dissipating breakwater downcoast of the floodgate should be retreated by 20 m landward with raising the crown height.

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 A large amount of sand was deposited in the wave-shelter zone behind the offshore breakwater of Otsu fishing port in Ibaraki Prefecture, which was much smaller than the eroded volume of sand on the Kamioka-kami and Isohara coasts located south. Because the possibility of sand transport from the further south coasts was considered as the cause, the shoreline changes in the entire study area were analyzed using aerial photographs along with the analysis of the change in volume of sand on coasts. As a result, in a period between 1975 and 2009, the volume of sand has increased by 7.0×10⁵m³ in an area of 4.5km length between Otsu fishing port and the Tenpisan Rock, whereas the volume of sand has decreased by 8.4×10⁵m³ in an area of 13km length between the rock and Takado Point, indicating that the Tenpisan Rock is not a solid boundary for longshore sand transport.

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 The development of sand spits with rhythmic shape and the segmentation of the lake due to the effect of wind waves in the lake were investigated along the eastern lakeshore of Lake Saroma in eastern Hokkaido by field observation. The segmentation of a shallow water body with triangular shape was studied using the BG model (a 3-D model for predicting beach changes based on Bagnold's concept). The features observed on lakeshore in Lake Saroma were explained well using this numerical model.

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 There has been increasing interest in preventive effect of coastal forests against tsunami especially since the Great East Japan Earthquake. The information about where and how far beaches exist adjacent to coastal reserved forests throughout Japan is essential not only to disaster prevention against tsunami but also to discussion about regional policy on environment and utilization of coasts.
 In this study, the location and the length of beaches adjacent to coastal reserved forests, which are not published in national statistical information about coasts, were estimated by using GIS and existing statistical information published by Ministry of the Environment and Geospatial Information Authority of Japan. And, the estimated results were verified by interviewing departments of prefectural governments in charge of coastal management. Problems with management of beaches were also investigated by inter-viewing them about the existence and content of cooperation in areas adjacent to coastal reserved forests with departments in charge of forest management.

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 Funamanu Island is a coral cay with 0.8 km length located in Funafuti Atoll in Tuvalu, and is located 0.6 km west of Fongafale Island with the capitol of Tuvalu. On this island, a large amount of gravel was transported from the offshore zone during Tropical Cyclone Bebe that hit the island in October, 1972. The changes in configuration of the island and the deposition of gravel were investigated using aerial photographs in July 1971 before the cyclone and in August 1984 after the cyclone as well as the satellite image in June 2010. Field observation was also carried out to investigate beach condition of this island and measure the topography of the coral cay.

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 On Makuhari Beach located in Tokyo Bay, artificial beach was built in front of the reclaimed land in the 1980s, and this beach has been widely used for recreation. However, the beach was gradually eroded. In 2009, a groin was extended in the middle of the beach and gravel with grain size of d = 50mm was nourished by 12000m³ between the jetty and this central groin. Although artificial beach was produced in parallel to the seawall line, nourishment gravel was transported northward and was deposited to form a high berm. In this study, the movement of nourishment gravel was measured by field observation.

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 The degree of abrasion caused by wave-induced gravel attack was measured for concrete blocks settled in Suruga, Fuji, and the Shimoniikawa coast. The depths of erosion were greater on older blocks, and the effects of block elevation and wave height were determined by multivariate statistics. A new accelerated abrasion test was developed to evaluate the resistance to abrasion and puncturing by gravel, and the relationship between the accelerated test results and the degree of abrasion measured on the coasts was investigated. The degree of geosynthetics deterioration was slightly higher for the accelerated test results than for the results of the exposure test carried out on the gravel coast. These results indicate that the newly developed test method is sufficiently reliable for evaluating the endurance of geosynthetics on a gravel coast.

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 Coral cays are low-lying island which is formed by the gravel on the coral reef, in this position slightly higher than a field. In past research, there are reported that have been formed by loss and its terrain changes in short-term of high waves. But many parts of the mechanism are unknown, because it is difficult to obtain observation data. In this study, we investigated the mechanism for changing the terrain by hydraulic model tests and field surveys on Barasu island where is near north Iriomote Island.
 As a result, the following conclusions were obtained. (1) Although geographical feature change of deposition, erosion, and movement is repeated by the strong external force by the short time of a typhoon, the moving direction of an island is agreement with the excellence direction of the external force which made the flow the subject. (2) At the coral gravels which is mainly by branch coral, we confirmed that 0.7 m/s is to be critical flow velocities for movement near bottom in general.

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 Artificial changes around a coral cay caused by human activity were investigated using the BG model (a 3-D model for predicting beach changes based on Bagnold's concept). Numerical simulations of beach changes on a coral cay were carried out after the successive construction of detached breakwaters. After the construction of the breakwaters, tombolos formed behind the breakwaters owing to the wave-sheltering effect of the breakwaters. As a measure against beach erosion on both sides of the detached breakwaters, further measure was required, and finally, the entire shoreline of the coral cay was covered by detached breakwaters, resulting in an artificial coastline.

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 Mechanisum of generation of a large scour hole in the opening of artificial reefs and sand accretion of a port entrance due to alternations of the reefs at Uradome Beach in Tottori Prefecture were investigated by bathymetry survey results and a three-dimensional morphodynamc numerical model. The causes of the large score hole were due to alternations of the crown height and the width of the artificial reefs. In order to examine optimum measures against the scour hole and the accretion problems of the port entrance, the numerical analysis were conducted. From the numerical analysis, we found that the construction of a submerged breakwater in the opening of the reefs is one of the effective measures in order to prevent the large scour, however, the magunitude of lognshore currents behind the reefs become large and the sand accretion of the port entrance aggrevats. To prevent the accretion of the port entrance, nereshore currents should be controlled by submerged breakwaters near the port entrance.

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 A method for enhancing sand deposition effect of the artificial reef constructed on the Hamaju coast was investigated using the BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept). Because it was considered that the shoreward currents on the reef should be reduced for mitigating beach erosion shoreward of the reef, a high crown type was proposed. Using this type, we can reduce the wave transmission coefficient and improve sand deposition effect.

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 Field investigation on the stability and the foot protection effect of gravel beach was carried out at Yamanishi area of the Ninomiya coast. The changes in longitudinal profiles and grain size composition were investigated along with the observation of sand movement using color sand. Although gravel beach extends along the seawall of the highway on this coast, the gravel layer was stable against storm waves, and gravel placed near the shoreline was maintained near the shoreline after the storm waves and transported toward the foot of the seawall.

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 On the basis of the aerial photographs taken between 1952 and 2010, bottom sounding data and narrow multibeam survey data, which were taken in November 2008 and January 2010, beach changes of the Kanbara coast were investigated. This coast extends on the right hand side of the Fuji River flowing into Suruga Bay. Off the coast a submarine canyon develops with a very steep slope, so that several new-type offshore breakwaters have been constructed as a measure against beach erosion. Not only long-term beach changes but also topographic changes around these offshore breakwaters were analyzed.

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 Local scour is one of the important problems in the pile-type structures will affect the stability of the structure. Because it is important to understand the mechanism. When dealing with local scour in hydraulic model tests, it is necessary to pay attention to the similarity law by scale effects. In this study, we conducted a field observation with the aim of capturing the temporal change of ground level directly under the pile. As a result, we were measured the temporal change of local scour around the pile, which proceeds scour depth in response to an increase in waves, decreases in the decay time. In addition, as a result of a reproduction experiment was conducted by focusing on the similarity law in the form of sediment movement, we were reproduced accurately the maximum scour depth and the temporal change of local scour.

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 The environmental improve experiment of marine pollution due to the eutrophication of the sea bottom sediment has been done. Then, various methods have been used to understand the mechanism of purification and to evaluate the results of the field experiment. In this paper, the observation and evaluation methods for covering sea bottom sediment by GCA were considered. And, new observation methods to evaluate the environmental improvement were used. The new methods for the sinking experiment of GCA layer, the measuring of sludge depth, the evaluating of GCA effects were produced. These results make clear that these are suitable methods for the evaluation of GCA covering technique.

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 The Yatsushiro Sea in central Kyusyu, southwest Japan is representative enclosed sea in Japan. Recently, various environmental degradations are reported in Yatsushiro Sea, as red tide and anoxic water. In this study, we clarified distribution of sediments and benthos in Yatsushiro Sea by using claster analysys. As a result, pH and temperature showed a constant value. Total sulfide and mud component are strong value in Yatsushiro Sea inner part. In the benthos resalt, we suggested benthos is affected by nutrients and total sulfide.

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 In order to verify the effectiveness of new sediment improvement technique that covering on seabed with granulated coal ash, we have monitored over the two and a half years since the experiment began at the Kaita Bay. Two and a half years later, the suspended mud thickness above the covering layer was about 2cm. This thickness is almost half that of the sedimentation rate at the Kaita bay. It indicated that suspended mud redeposit to covering layer was containment because of the function that suspended mud trapped by void structure on covering layer. Another function of this technique that means removal ability of hydrogen sulfide and nutrients or tempered hypoxia had been continued. Consequently, the benthos biomass was increased after experiment, and species composition succession from r-selection species to kselection species. We concluded that this new technique induce positive spiral for coastal environment through the physical and chemical function has been continued over 3 years and recovery the benthic ecosystem.

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