Accurate prediction of relatively small waves is required to determine whether or not offshore construction can be carried out. In addition, it is important to be able to accurately judge whether a certain threshold value is exceeded or not, rather than the value of the wave height itself, when making such a judgment. In this study, we developed a prediction method that combines machine learning and meteorological ensembles with the goal of achieving a high success rate in determining whether a threshold is exceeded for small wave heights. The wave heights were predicted from deep neural network models using ensemble meteorological data as input data, and an optimal value was obtained by Bayesian estimation using the obtained wave ensemble. The results showed a high accuracy rate, which confirmed the usefulness of the method. It was also found that the method of taking the majority vote of the ensemble data predicted from the classification model, which is directly used to determine the threshold exceedance, also could yield a high accuracy rate.

 The recent studies introduce machine learning-based wave prediction models using the Group Method of Data Handling (GMDH) and Artificial Neural Network (ANN) for one-week wave prediction along nearshore coasts in Japan because global wave forecast models predict waves on large spatial resolutions, being unreliable for nearshore wave predictions. The current study develops the GWM to XGBoost nearshore wave prediction model that transforms global wave model GWM forecast waves to nearshore ones. The XGBoost method is one of the machine learning techniques that the ensemble training method improves the discrimination efficiency by combining multiple-decision trees. Then, the study discused the accuracy of the GWM to XGBoost nearshore wave prediction model, and showed a good performance.

 In the inspection of breakwaters and quays of fishing port facilities, most of the facilities are underwater and visual observation surveys by divers are mainly conducted, so the diagnosis results vary and lack objectivity, and a great deal of labor is required for the survey. It has been pointed out that it is necessary to improve and simplify the inspection method using sensing technology.

 The authors have used the narrow multi-beam and underwater 3D scanners of underwater acoustic equipment, which are part of the sensing technology, to show their effectiveness as inspection methods, as well as their accuracy and applicability. In this paper, we clarified the application conditions of both devices in a field test with the aim of introducing them into actual inspection work. We also proposed an inspection method using point cloud data using an underwater 3D scanner and image data using a UAV for inspection of offshore structures that are difficult to visually observe, and verified its effectiveness.

 Targeting the promotion of ICT implementation towards work-style reform, the author has clarified, by analyzing data monitored for sales operations and interviewed from the persons concerned, that the computerization of auction and bidding sales is effective in preparing and issuing invoices as well as reducing the labor and the time required and the lead time between receiving and shipping fish products. The measurement of the benefits of ICT implementation has also been obtained through this analysis.

 The tsunami load is not only associated with hydrodynamic force but also collision force of drifting objects on the tsunami, such as debris and containers. Although the impact force of the tsunami drifting object on the structure has been numerically simulated so far, the numerical simulation of the trajectory of drifting objects has not been so much evaluated. In this study, the behavior of drifting containers on the apron was simulated by using DualSPHysics on the experimental scale, and it was compared with the previous hydraulic experiments. As a result, the wave height and flow velocity measured on the previous experiment could be well reproduced by using the numerical simulations. In addition, regarding container trajectories, the drifting forward distance of the containers was significantly underestimated compared with the previous experiment. On the other hand, the diffusion angle of containers was well reproduced in the numerical simulations. As a summary, it was confirmed that the container drift orbit analysis was enabled by using DualSPHysics with the limitations on the forward distance of containers.

 In recent years, numerical models have been increasingly applied to research and practice in the field of coastal engineering. DualSPHysics, an open-source fluid simulation code based on SPH, is expected to be applied to the design of coastal structures because of its capability of GPU calculation. This study verifies the applicability of DualSPHysics to the evaluation of tsunami wave pressure acting on land structures. The computational accuracy and cost were compared with the results by OpenFOAM. When using the boundary condition mDBC in DualSPHysics even at low resolution, the results corresponded well with the experimental results. OpenFOAM has higher computational cost but can evaluate tsunami pressure accurately except for impulsive pressure. Considering the computational cost, DualSPHysics with mDBC is more applicable model to the evaluation of tsunami pressure on land structures.

 The Anti-Tsunami Door (ATD) is a foldable and movable tsunami mitigation facility that automatically stands up to prevent the intrusion of waves when a tsunami occurs. In this study, the conditions required for the practical application of the ATD were examined from both the hydraulic model experiment and the numerical analysis. A numerical analysis model was constructed using OpenFOAM, and the tsunami mitigation effect was evaluated. The method of evaluating the performance of the ATD using only the measured wave height was inappropriate because the net tsunami mitigation effect of the embankment body could not be properly evaluated. On the other hand, the evaluation using the passing water volume data was applied to expect the tsunami reduction effect of the embankment body. The tsunami mitigation efficiency of the ATD was 70% or more. The strength analysis of the ATD was also done in the paper.

 Wave dissipating performance of long-period wave absorbing mounds having a water chamber was investigated by hydraulic model tests. It was found that the mound with a water chamber was more effective when the tide level was low and the crown of the mound was exposed. It was also found that the wave dissipating performance was improved by setting the crown height of the mound a little higher than the mean water level, when the non-dimensional structure width (B^’+B^*)/L was less than about 0.08. In addition, numerical analysis based on the VOF method was conducted to reproduce the hydraulic model experiments. It was shown that the reflection coefficients can be estimated accurately by using the measured coefficients for the resistance in the permeable layer and considering the effect of the KC number.

 Emerging as a powerful computational fluid dynamics (CFD) tool in recent years, open-source software is receiving attractive attention. The trend to use open-source software is expected to be increasingly stronger since current open-source software has many features and qualities comparable to a commercial one. Despite the importance of verification of accuracy in basic benchmark problems, open-source software has a tendency to be applied without adequate prior review. OpenFOAM and DualSPHysics are open-source software with potential applications in ocean engineerings. In this study, we have compared OpenFOAM and DualSPHysics for non-Newtonian fluid analysis through the benchmark tests of the Poiseuille flow and slump test. We have demonstrated that both models are robust tools for the analysis of non-Newtonian fluid flows. The main practical contribution of this work is to reveal the advantages and disadvantages of each software, which cannot be seen by just applying each software, and to multifacetedly discuss the applicability of OpenFOAM and DualSPHysics in the marine development engineering.

 In recent years, damage caused by wave overtopping has become more frequent due to the arrival of more intense typhoons affected by global warming, and the design of offshore waves is being reviewed nationwide. As a result, the design waves are expected to become larger, and the demand for wave dissipating works is expected to increase as a countermeasure against wave overtopping. In the design of seawalls, Goda's wave overtopping discharge estimation charts are used to estimate the amount of wave overtopping, but they are interpolated even when the conditions such as the cross-sectional shape and the covering type of the wave dissipating works are different. In this study, the hydraulic model experiments of full-section covering type wave-dissipating works covered with wave-dissipating blocks up to the top of the revetment with reference to the construction cases were conducted and the wave overtopping discharge estimation charts were developed. Experiments were conducted under the same conditions for the two-layer covering type, and the effect of the covering type was quantitatively evaluated. In addition, the applicability of the proposed overtopping flow estimation equation by CLASH database and the Integrated Formula for Overtopping and Runup Model (IFORM) was confirmed.

 Mangrove restorations have been implemented in many countries, but the success rate is still not very high. It often fails during the initial stage of plantation due to various negative environmental impacts. In particular, high waves may cause the failure of young seedlings. A series of field surveys were conducted in a mangrove forest of Amami Oshima, Japan, in May and December 2019. Mangrove growth tests were carried out for observing the growth rate of young mangroves by planting several seeds of Kandelia obavata. In a manual wave experiment in the site, a one-month-old mangrove plant had bent and submerged due to continuous wave impacts of 10 cm high in maximum, while a six-month-old mangrove was undamaged. For investigating whether young mangroves are protected with a small breakwater, a portable reef was designed using the conventional design formula for rubble-mound breakwaters. The wave-dissipating performance of the reef was examined by the CFD model using olaFlow/OpenFOAM. Four breakwater geometries with a similar cross-sectional area were tested for local wave and tidal conditions in the mangrove forest of Amami. The numerical results showed that the mounds with an area of about 1m² can attenuate the wave heights by 48-82%. Although wave transmission varies depending on the geometry, a small rubble mound breakwater would sufficiently work to protect mangrove plants in their early growth stage.

 This study confirmed that the characteristics of increasing the wave run-up height under the wind blowing condition differ depending on the presence of wave breaking in front of the revetment. In the case of non-breaking conditions, the run-up height tends to increase exponentially with the wind speed. In the case of wave breaking conditions, the effect of the wind on the run-up height is extremely small. The amplification of waves by the wind greatly influences on the increase of relative run-up height observed in the case of non-breaking conditions. In addition, the effect of wind stress acting on the mass of water running up the revetment is seen in the situation where the wind speed increases sufficiently. An exponential function with wave steepness in front of the revetment could be used to assume the increase of the relative run-up height with respect to the wind speed. The effect of the wind speed on the bottom velocity at the foot of the revetment is extremely small.

 A slit caisson is one of the effective measures to reduce wave overtopping particularly if the height of a target seawall is limited, such as at airports. However, the performance of the slit caissons on the wave overtopping may not be sufficiently effective when the water chambers are submerged during high tides. And the quantitative evaluation of the effect has not been sufficiently studied. In particular, it is difficult to reduce the wave overtopping by only the slit caissons due to an increasing overtopping wave rate at the corner of the seawalls due to the convergence of waves. In this study, the height coefficient of the slit caisson is evaluated when its chamber is submerged in the water. And the variation tendency of the overtopping wave rate is investigated between the case of direct incidence and non-direct incidence of the waves against the corner. In addition, it is shown that the overtopping flow rate at the corner can be effectively suppressed by installing a simple wave return wall as an additional countermeasure to the slit caissons.

 The bottom boundary layer under wind waves is extremely thin compared to the water depth, but its thickness increases as the period increases. Therefore, it is often assumed that a current-like flow is formed under a long wave such as a tsunami or a tide, and the steady flow friction coefficient is used. However, the transition process from the wave type to the steady flow type boundary layer is not clear. In this study, we investigated the transition of the wave boundary layer for smooth surface turbulence and formulated the transition conditions based on the results of previous experiments and newly conducted numerical experiments. In addition, a modified simple formula was derived to judge the transition condition by using the linear long wave theory in terms of the relationship between the wave height/water depth ratio and the water depth/wavelength ratio. From this result, it was found that there is a wide range in which the steady friction law cannot be applied even if it is classified as a long wave. Hence, it is necessary to appropriately reflect such transition of the boundary layer in a simulation of tsunami-induced sediment movement.

 This study investigated the stability of the counter-weight block (CWB) against tsunami-induced current through breakwater openings was investigated by hydraulic experiments; CWB was originally developed as reinforcing countermeasure for breakwaters against tsunamis and waves. The Isbash formula was used to evaluate stability of CWB. It was found to be difficult to evaluate the Isbash number based on the flow velocity alone since the Isbash number varies with the model scale and initial water depth. However, it is possible to properly evaluate the Isbash number using the Froude number. In addition, it was clarified that the fluid force on the CWB was highly correlated with the Fluid number, and the stability assessment of CWB is possible to use the Fluid number.

 The tsunami which run-up in river over the embankment affected serious damage in coastal area at the 2011 Tohoku earthquake and tsunami. Therefore the measures to river run-up of the tsunami were important in thinking about the tsunami disaster prevention in the coastal area. On the other hand, there were few records of the tsunami data, though active faults were near the land on the Sea of Japan side and time to tsunami arrival from an earthquake occurrence tends to be short. Therefore it was simulated based on 1983 Japan Sea Earthquake to perform the comparison with the measured value with Sea of Japan side particularly.

 The following things were confirmed from a calculation result and measured. It is thought that the tsunami sediment in this area is of the sea origin at Takogawa River. (1) The tsunami run over the beach bank, (2) The tsunami flowed into the small river, (3) The flow to return to the sea from the east side in the right bank the small river was confirmed at Shirayukigawa River

 The flap gate type breakwater lays down on the seabed in normal times to secure the passage of vessels, and when a tsunami or storm surge is predicted, it floats above the water surface and closes the route to prevent inundation damage. Development of this technology was started in 2003, and after three years of actual sea area tests from 2011, it was first adopted in the tsunami countermeasure facility conducted by Iwate Prefecture in 2017. In the detailed design, we paid attention to the maintainability after the equipment was completed, and in the on-site construction, we paid attention to the construction method of the on-site joining between the bottom structure of the flap gate type breakwater and 56 steel pipe piles, which were expected to be difficult. Through a field test run, we confirmed the operating characteristics of the gate in the actual machine and confirmed that it satisfied the specified performance. Construction was completed successfully in December 2020.

 The 2011 Great East Japan Earthquake and Tsunami attacked Japan on a scale far beyond conventional expectations. Buildings, automobiles, and ships were swept away, and a large amount of drifted debris caused catastrophic damage. In the event of a tsunami, evacuation methods using floating tsunami evacuation shelters have been proposed, and the behavior and wave forces of shelter models installed on buildings have been investigated. In this paper, we propose a method of evacuation using a floating tsunami shelter. In this study, a pressure sensor was attached to a drifting object model and a tsunami impact experiment was conducted to examination the wave force in the drifting condition. For this results, the maximum value of the wave force and the behavior of the model differed depending on the inundation conditions. Furthermore, it was found that the wave force was overestimated by fixing the model.

 Many of the breakwaters were damaged by the 2011 off the Pacific coast of Tohoku Earthquake Tsunami. It is thought that these were caused by the strong current behind the breakwater caused by the overflow at the top of the breakwater, which scoured the foundation mound. However, the technical standards in Japan mainly focus on composite breakwaters, and do not refer to other structural types. In this study, hydraulic model experiments and fluid analysis were conducted to investigate the structural resistiveness against tsunami action of the port side armor blocks of a sloping breakwater with a capping concrete.

 As a result, it was found that the location and degree of damage varied depending on the tide level at the time of tsunami attack, and that it was necessary to consider seepage flow in the case of sloping breakwaters.

 It has been reported that there is uncertainty in motion of a tsunami debris object on horizontal land, and the motion is highly affected by the initial condition of an object. This study aims to experimentally investigate the effect of the initial setup angle θ₀ of a rectangular object on its motion induced by a tsunami. An object which initially had a face inclined in tsunami flow could move laterally in the flow. The lateral movement also depended on an angle of the object in the flow, which was especially varied by object’s rotation in an initial phase after the object started to move. In the case of an object with θ₀ =30 degree, there was especially a case that an object moved in the direction of 16.7 degree from the initial position. The standard deviation of lateral movement was modeled with the flow-down distance multiplied by 0.04, independent of the initial angle. Two objects closely arranged each other showed different patterns of movement from a single object by their interaction.

 This paper presents a case study of the rulemaking process for the evacuation of fishing boats in the event of a tsunami for Omoe Cooperative Association in Miyako City, Iwate Prefecture. As a result of examining and analyzing the evacuation of fishing boats during fishing work under the situation where the first wave of a tsunami has arrived in the middle of evacuation from a tsunami, small outboard motor boats were found to have a problem in staying on the sea for a long time to evacuate from the fishing sea area to the sea area to evacuate. When examining the evacuation from the fishing sea area to the safe higher ground, we do not adopt the first wave arrival time for setting the time from the earthquake occurrence until mooring to a quay becomes difficult. Instead, we adopt the shortest one out of the following three: (1) the time when fishing boats become difficult to navigate due to the flow velocity of a tsunami at the fishing port entrance after the earthquake occurrence, (2) the time when the flow velocity exceeds the berthing speed, and (3) the time when a tsunami overflows a major quay. As a consequence, it has become clear that it is important to examine the evacuation possibility of fishing boats by comparing the abovementioned time with the time to evacuate from the fishing sea area to the safe higher ground.

 The Tsunami occurred at offshore of Yamagata prefecture by the strong earthquake in 2019. Furthermore, the small tsunami occurred and tsunami warning was announced by Japan Meteorological Agency. Fortunately, there was no tsunami damage in the region, however, some tsunamis by the earthquake sometimes occurred around this region in recently years. Therefore, the residents that live near the coastal area and the government always need to concern about some tsunami countermeasures. We grasped this tsunami dynamics and the behavior of the residents and the government when the earthquake and the tsunami occurred. Firstly, we simulated the tsunami dynamics. Secondary, we grasped the status of the information transfer systems and behavior of the government. Finally, we made the questionnaire survey to the residents, and grasped the behavior of after occurring the earthquake.

 In order to investigate the process of the human model being caught in the tsunami-derived vortex, and to clarify the force induced by the vortex and the necessary buoyancy to resist the vortex, a large vortex caused by a solitary wave was reproduced inside a large wave flume. As a result, followings were clarified. 1) When a tsunami (solitary wave) with a wave height of 0.2 to 0.5 m acted on the human model, the human model was caught in the vortex behind the concrete block and pulled into the depths. 2) The centripetal force and buoyancy force acting on the human model were calculated from the rotation radius and angular velocity of the vortex, and 3) the human model wearing a life jacket floated on the sea surface. 4) When rotating around an axis perpendicular to the axis of the body, the centrifugal forces act on the hands, the legs and head with a maximum acceleration of 12 m/s² (1.2 G) in a tsunami with a wave height of 0.5 m.

 A large-scale hydraulic experiment was conducted in a large basin to investigate the scour and stability of the breakwater head at the mouth of Urado Bay due to tsunami. In this study, a new surveying method was introduced to precisely measure the ground height under water using a laser displacement meter. As a result, the followings were clarified. 1) The frequent tsunami caused scour hole up to 8 m in depth at the Tanezaki breakwater, resulting in scattering of rubble mound, armor blocks and sliding of caisson. 2) The largest tsunami caused severe scour and caissons to roll and move more than 50 m. 3) The scour around the head of the breakwater is estimated to be caused by the fast flow from the surface layer outside the harbor to the bottom layer inside the harbor.

 In order to develop user-friendly ferry terminal, public-private collaboration is important in making new layout plan of the ferry terminal. However, it is difficult for the public organization to consider layout planning based on the terminal operator feedbacks since the public organization, such as national government and port management body, usually don’t know much about actual terminal operation. This study develops Discrete-Event simulation model for new ferry terminal in port of Takamatsu and presents how the model is utilized in designing the new ferry terminal layout. Through the case study, the advantages of use of simulation model are discussed.

 After the enforcement of the law on offshore renewable energy utilization, proposals of offshore wind power generation have become active in Hokkaido. It is necessary to obtain widespread support from the citizens toward to large amount of offshore wind power generation. This paper describes trends toward the development of offshore wind power generation in Hokkaido. In addition, the authors show the results of a questionnaire survey on the awareness of offshore wind power generation for students and citizens conducted from 2017 to 2019, and describe the factors that affect the awareness of offshore wind power generation.

 Delay of container services is the big problem in recent years. One of the causes is considered the concentration of calling at specific ports and terminals, which had been induced by revision of alliances.

 Based on this background, this study analyzed offshore waiting time, which is the main factor of delay, in world container terminals. Waiting time of each ship was calculated by spent time from port entry to berthing by utilizing AIS data. From the result, it was revealed that offshore waiting time of each terminal linked to berth occupancy ratio, delay of berthing ship, and characteristic of schedule.

 There are from 2,000 to 3,000 rescues every summer season on the beaches of Japan. At the time of drowning, a "help signal" is recommended worldwide as a rescue request sign. But it is not easy to find it because one life saver monitors over 1,000 beach users. On the other hand, in previous research, efforts have been made to automatically detect a help signal using AI. However, the video used for AI learning in the previous research was shot in winter, and there are no users other than the drowning victim (subject), and the subject is close to the camera and always faces the front to the camera. Therefore, we developed an AI that can detect help signals under multiple conditions where drowning may actually occur. Three AI models were developed using the object detection algorithm YOLO v3. As a result, the AI model which has most high accuracy was possible to detect help signals with 87 % F measure.

 When considering tsunami disaster prevention measures, it is important not to interfere with local industry and daily life. From this point of view, the local government and local residents in the coastal area of the Izu Peninsula have established the "Tsunami Countermeasures District Council" to promote tsunami disaster prevention measures that match the regional characteristics. Therefore, this study clarified three types (sightseeing spot type, steeply sloping land type and small fishing village type) and their characteristics based on the relationship between tsunami disaster prevention measures and regional characteristics in that council of the eastern Izu peninsula (12 districts of Atami city and Ito city).

 Itsukushima Port, which is the gateway to Miyajima, Hiroshima Prefecture, is the regional port in Japan with the largest number of passengers. In recent years, due to the rapid increase in tourists, problems such as worsening traffic congestion, aging piers, and lack of stagnant space have become apparent. Therefore, the Miyajimaguchi district renovation project was implemented. In this study, for renovation of harbor and town corresponding to inbound, the implementation process of this renovation, the characteristics and points to be noted of port facilities and terminal renovation, the effect on project implementation and the future way were considered.

 Green infrastructures, such as mangroves and pine forests, have not yet been practically incorporated into the design as part of protective infrastructures, despite its attracted advantage related to environments. In order to treat the green infrastructures as the protective facilities, it is necessary to calculate the life-cycle cost of the green infrastructures accurately with considering their changing performances against waves. In this study, the relationship between the width of the forest zone, the density of vegetation and the wave attenuation effect on mangroves is developed based on the results of existing experiments. And the optimal combination of gray and green infrastructures is investigated in relation to the overtopping wave rate. In addition, the variation tendency of the life cycle cost depending on the condition is examined, and the variation of the cost which incorporates the future prediction such as the expansion of the width of the forest zone and the change of the wage to construct the infrastructures is also examined.

 The Covid-19 pandemic was an historically significant incident in that it was the first pandemic at the world level in the last 100 years. The pandemic has been affecting significantly to the international logistics sector including shipping carriers. One of the striking features of the incident is that different interested parties (carriers, ports, shippers, and government bodies, etc.) are having impacts, and they took different countermeasures.

 The purpose of this study to overview and compare countermeasures during the pandemic, and to propose measures which should be taken in the future, so that the related knowledges on the logistics sector can be accumulated for appropriate responses in the future.

 It is indicted that COVID-19, which has been spreading worldwide from the beginning of 2020, has caused significant impacts on the world economy and maritime transport. The aim of this study is to quantitatively grasp the impacts of COVID-19 on shipping industry using PIERS and Lloyd's data, in order to provide necessary information for organizations to formulate policies, and for shipping industry to make responsive actions.

 As a result, several facts have been found. Firstly, container cargo volume from Asia to the US fluctuated significantly, affected by the changes of productions and consumptions. Secondly, the fluctuation is mainly caused by the increase of demand for some types of commodities such as furniture. Thirdly, increase of transshipment at Japanese ports were observed. Finally, the number of calls by cruise ships and pure car carriers substantially dropped while those of container ships and bulk ships did not drop significantly.

 Since March 2020, a new type of coronavirus (Covid-19) has spread all over the world, and it is effective to avoid crowding of people as one method of preventing the spread of infection. On the other hand, in the summer of 2020, about 40% of the beaches were closed nationwide, but many users visited in some areas. In the absence of the convergence of Covid-19 infection, appropriate infection prevention measures will be required in the summer of 2021 as well. A situation of beach usage in 2020 will help examine infection prevention measures, and it is effective to provide quantitative information for risk management by users themselves. In this study, we investigated it including a human density using AI from images taken by fixed cameras at a beach and compared the coastal usage in the summer of 2019 with that of 2020, which was under the Covid-19 crisis. As a result, there were many users on weekdays in 2020, and the peak time zone of the number of users was shifted from 13:00 to 14:00 during the day, so it was considered that the usage situation avoided the concentration of people. However, the crowds of people within 2 m were high on Sundays and around peak hours.

 "Blue carbon", absorbed carbon by photosynthesis in coastal and ocean ecosystem, has been paid attention to as climate change mitigation. The carbon absorption rate varies when seagrass bends due to current, suggesting the necessity of precise estimation of carbon absorption by the blue carbon ecosystem. We developed the Submerged Aquatic Vegetation model (SAV model), which combines SAV motion and its interaction with the current. Therefore, this study aims to verify the SAV model's validity by applying laboratory experiments in an open channel assuming low-density polyethylene as SAV, which agreed with the laboratory experiments.

 The steel pipe sheet pile quay wall with press-in method, which is new technology developed in Japan, was adopted in the Grant Aid project at Dakar Port. Although this technology didn’t have enough experience in Japan, it was introduced in ODA project as a reliable technology. To introduce this new technology, a technical consultation committee, which was comprised of experts, was set up to examine the technical issues. As a result of the examination, it was concluded that the press-in method could be adopted for casting even on rocky ground. For introducing the new technology in this project, the structural details were adjusted according to the request of the recipient side.

 We believe that the policy of “Quality Infrastructure Investment through the World” will be realized by accumulating the experience by the recipient countries on Japanese high technologies. In this paper, we clarified the basic procedures, advantages, and points to note when introducing the Japanese new technology in ODA Grant Aid project.

 The standard values of tractive forces of moored ships used in mooring post design are described in the Japanese technical standards for ports and harbors. They were set based on the calculation results of the tractive forces by the simulation of oscillation for moored cargo ships subjected to wind loads. On the other hand, wind pressure areas are so large for container ships and passenger ships compared with cargo ships. It is therefore more appropriate to select mooring posts and bollards by using the tractive forces calculated by the simulation of oscillation for moored ships. In this study, we carried out the simulation of oscillation for cargo ships, container ships and passenger ships subjected to wind loads. We then compared and evaluated the influence of ship types on the tractive forces acting on mooring posts and bollards. We also confirmed the applicable range of the standard values of tractive forces in the Japanese technical standards.

 Two-dimensional hydraulic experiments were conducted using a reversed triangular bottom-hinged flap with the reflection wall behind it. Electricity generation performance when the power take-off system is installed was evaluated from the experimental result based on linear theory. Efficiency is lowest near the antinodes of the standing waves. There are some cases in which D/L when efficiency is highest is slightly different from nodes depends on wave period. Efficiency is high when the wave period is short and the water depth is small. There is a possibility that there is a specific wave period in which efficiency is extremely high. The increasing ratio of efficiency by installing the wall reached 6 at most and 2 at least.

 A steel platform with concrete bottom plates has been constructed as a mooring facility for small boats in a fishing port. Rubber protectors covering the steel piles were damaged due to the collision of rubble stones activated by the wave action during under construction stage. This study clarified the moving patterns of rubble stones in front of the steel platform by random wave experiments at a scale of 1/30 for the wave and tidal conditions when the damage happened. In addition, the characteristics of moving speed of the sphere type model for the maximum wave condition were examined by dam-break wave experiments at a scale of 1/10. The relationship between the collision force and the flow speed was shown based on the momentum conservation law. As a result, it was shown that the collision force was peak for the typical diameter conditions.

 A model experiment was conducted in a wave basin for the purpose of understanding the reflection characteristics and wave overtopping characteristics of the slit caisson with respect to the obliquely incident waves. At the same time, the method of measuring and analyzing the reflection coefficient of obliquely incident waves in the three-dimensional model experiment was examined. The two points wave gauge method, and the one point wave and current gauge method were applied to the wave reflection analysis. The accuracy of the wave reflection analysis was improved by using wave data considering the difference in wave height that occurs in the experimental area. Experiments were conducted with three types of incident angles: 0°(perpendicular), 20° and 39°, and it was found that there is no significant difference from the reflection coefficient of perpendicular incidence and in the case of oblique incidence. In addition, it was confirmed that the reduction in wave overtopping by the slit wall could not be obtained under the condition that the slit wall was almost submerged, and it was found that the wave overtopping quantity can be estimated from the calculation chart of Goda et al. by treating it as an upright wall.

 In recent years, the frequency of high waves that hit coastal roads has been increasing in accordance with the sea level rises and wave heights increase, causing frequent embankment damage on coastal roads. In this study, the wave estimation is carried out based on the damage caused by the collapse of the road slope caused by the run-up wave and overflow that acted on the road slope behind the retaining wall. Furthermore, we clarified the damage mechanism of the road slope depression by the moving bed experiment regarding the erosion of the road slope in the cross section at the time of the abnormal occurrence of the disaster and the external force.

 In the construction of rubble mound, damage to the rubble mound by high waves is a problem. Hydraulic model test and numerical analysis are considered to be the methods to verify the damage of rubble mound. In the numerical analysis, the Distinct Element Method(DEM) and the particle method are generally considered, but these methods are computationally demanding. In the construction field, it is necessary to predict the extent of damage as soon as possible. The authors focused on the fact that the damage process of rubble mound is similar to the advection-diffusion phenomenon.

 In this study, the one-dimensional advection-diffusion equation was solved by the finite difference method to reproduce the damage process of rubble mound. The advection velocity C and the diffusion coefficient ν were tuned based on past experimental data. As a result, the reduction of the crest elevation was reproduced by setting the diffusion coefficient ν, and the deformation to the shore was reproduced by setting the advection velocity C. Although this method is completely new, some issues remain. However, since this method is very simple, it is expected to be extended to 3D in the future.

 The evaluation of wave forces acting on caisson breakwaters with deformed wave dissipation works is important to maintenance. A series of hydraulic experiments was conducted to investigate the relationship between wave forces and deformed wave dissipation works using regular and irregular waves. The caisson breakwater with a relatively lower crest height compared to incident wave heights was examined in this experiment.

 The wave forces acting on the caisson increased when the magnitude of the deformation of the wave dissipation works increased. Although the wave forces increased with the increase in the incident wave height, the wave forces decreased in the cases where the incident waves were larger than the threshold depending on the crest height of the caisson.

 Port construction engineers has long recognized that the slipway, which is frequently set in a fishing port, has a reflection coefficient smaller than that on an upright breakwater and thus plays an important role in ensuring the harbor tranquility. In the harbor tranquility analysis, the reflection coefficient of the slipway is set with refer to that of the natural beach of 0.05 to 0.2, because there are few studies on the wave control function assuming the slipway in a fishing port. On the other hand, it has been pointed out that the reflection coefficient of the natural beach gets closer to 1.0 for long-period waves. In this study, we investigated wave breaking and reflection process on the slipway under regular wave condition using CADMAS-SURF V5.1. We confirmed that the reflection coefficient increases as the slope gradient becomes steeper or the wave steepness decreases, which is the same tendency as in the previous study under uniform slope condition. It was also shown that applying a uniform constant in the harbor tranquility analysis is not always appropriate. Using the results from numerical calculation and introducing the surf similarity parameter ξ₀, we presented a formula to find the reflection coefficient on the slipway in a fishing port under regular waves.

 The efficient and effective implementation of temporary structures such as sandbags, etc. for emergency restoration of damaged seawalls is being promoted in preparation for successive typhoons. However, there have been few studies on the stability of temporary structures on seawalls against waves. In this study, we performed large-scale hydraulic experiments to evaluate the stabilities of sandbags installed on seawalls. The experimental results showed that the damage rate of single-row, single-tiered sandbags is proportional to the wave pressure and that sandbags are more likely to be moved by tipping than sliding. The stability of sandbags was calculated by shifting the center point of the moment of force from the rear end of the bottom to the front, which was consistent with the experiment. In addition, we clarified the stabilities and damage mechanisms of multiple sandbags and connected sandbags.

 In order to promote a fossil-free energy policy, a stable supply of renewable energy sources is necessary. The development of wave power generation technology is desired as one of the means. In this study, the relationship between the frequency of flow velocity and incoming waves is investigated by measuring the flow velocity in a vertical slit wave dissipator, assuming that a water turbine is introduced into the port structure. The relationship between the wave characteristics in the slit-type caisson and the wave characteristics in the slit-type caisson at the Yumeshima seawall in Osaka is clarified from the observed wave characteristics in the National Ocean Wave Information Network (Kobe Port), and the estimation method of the velocity through the slit is proposed.

 Due to sea level rise caused by global warming and the intensification of typhoons, it is feared that storm surges will exceed the designed high tide level in the future. In this study, we evaluate the impact of rising of seawalls on storm surge inundation characteristics in order to discuss hardware mitigation measures against storm surge. Rising of seawalls reduces the overflow into the protected lowland by seawalls, and the sea water level rises due to the increase of sea water retained in the sea area. In this case, the water level rise in the sea area is larger at the inner part of the bay than the mouth of the bay due to the influence of the wind-driven surge. Therefore, it is suggested that the overflow volume may increase in the area facing the inner part of the bay, which may cause the inundation depth in the protected lowland to increase. In addition, the disaster mitigation effect of rising of seawalls was found to be different among municipalities.

 Port administrators and users are required to begin countermeasure actions three days or more prior to a storm surge event. Those who have neither simulator nor expert knowledge need the simplified diagram that can estimate the approximate storm surge height from fundamental typhoon parameters provided by the Japan Meteorological Agency. That is the background why we simulated the storm surges in and around Osaka Bay for various typhoon conditions and then produced the diagram for each port in the region. The diagram was examined with the tide records in Typhoon Jebi, 2018 and would be an effective tool for appropriately beginning the actions.

 Hurricane Dorian made landfall in The Bahamas on Sept. 1 2019 and is an extreme example of a common threat to tropical and subtropical coastal regions. With maximum sustained winds clocking in at 295 km/h, Dorian is tied with the Labor Day Hurricane of 1935 as the strongest category 5 hurricane to make landfall in the Atlantic. In The Bahamas, Dorian persisted for over 48 hours (over 24 of which were at category 5 strength) and resulted in catastrophic environmental, economic, and social damage, as well as unprecedented loss of life. Field surveys and data mining including SNS questionnaires were conducted immediately after the storm’s passage in Sept. 2019, and 6 months following in March 2020 in order to understand the storm surge impact. Storm surge magnitude was recorded at 84 points on the island of Grand Bahama. Storm surge inundation was found to be on the order of 8m above sea level, with approximately 70% of the island affected and flow direction was found to be highly influenced by topographical interaction with elevated ridges, creeks, ponds, and canals. Depending on the direction of storm approach and surrounding geography, property lying less than 8m above sea level can no longer be assumed safe.

 In this paper, numerical simulations of flow and local scour around a cylinder were carried out using various turbulence models in the RANS in order to clarify the turbulence model which can reproduce the flow and the local scour accurately. From the simulations of flows in a fixed-bed experiment, it was found that the SST k-ω turbulence model is the most suitable for the reproduction of the phenomena, and at least over ten-odd meshes for the resolution of a cylinder are required to reproduce the flow accurately. Moreover, from the simulations of local scour in a movable-bed experiment, it was shown that the difference between the RNG k-ε and the SST k-ω turbulence model or the effect of the non-equilibrium bed load transport are not clearly appeared in the numerical results under the target experimental condition.