Offshore wind farms have not yet been realized in Japan except for some near-shore plants although they are promising for sustainable economic growth with less CO₂ emission. This paper introduces a marine condition study for offshore wind farm design, by constructing offshore wind and wave observation system with 85m high tower from sea level and with Doppler typed Wave Directional Meter (DWDM) installed on the seabed 14m deep. Not only design and construction process of the system but also examples of the observed data are introduced in this paper.

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 This study estimated the accumulative probability curves and the annual and monthly statistics, such as the maximum, median, mean, and minimum values, of the 20-min-mean wave powers around Japan by using the significant wave database of the deepwater GPS buoys and shallow-water coastal wave gauges on NOWPHAS, and then examined the seasonal and inter-annual variations on these statistics. The examination led the following major conclusions; (a) During a year or a month an individual wave power can exceed the mean vaule over the duration with a probability of 20-40%; (b) The annual and monthly maximum and minimum values estimated from daily mean wave power datasets become around half and twice, respectively, as much as those from 20-min-mean ones; (c) A several-year-long dataset is recommended for the certain determination of wave power statistics because the inter-annual variations on the statistics are large; (d) The mean wave power and the median direction are almost constant among GPS buoys off the Pacific and Sea of Japan coast, respectively; and (e) These statistics on the coastal wave gauges are strongly affected by their surrounding bathymetry. Moreover, this study calibrated the signinfciant waves that are estimated by using the WAM model, and interpolated the mean wave powers in the months when the measurements are not available owing to the Great Tohoku Disaster effects.

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 The authors already have shown that the conversion efficiency of tidal current energy by a vertical Savonius water turbine is significantly improved by introducing outer ring type current controlling devices. In order to obtain much higher extraction rate of the tidal current power and also seeking a more simple structural form of guide vanes, a new type of guide vane was examined and proposed. The proposed guide vane in this study is composed of four vertical thin walls in axisymmetrical arrangement. We call it as a vortex-stream like guide vane. It was confirmed that the extraction rate of the tidal current power of a vertical Savonius water turbine becomes more than fifty percents by installing a new guide vane. Also the rotating torque by the turbine is significantly magnified, typically four or five times as large as the case without a guide vane.

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 This study was investigated to obtain some basic information for the influence of Tsunami associated with the Great East Japan Earthquake on the structural succession of the Hasunuma seaside park pond ecosystem located in Kujyukurihama coastal line in Chiba prefecture. This pond was under the eutrophicated state of hyper P loading, and Aoko of Anabaena spiroides was occurred in every summer season. For insecurity and complaint from citizen, sun exposure of sediment of this eutrophicated pond was conducted in 2004, 2009 and 2010. In spite of this attempt, Aoko was occurred again in summer and red tide of Cryptomonas spp. was observed in winter, and eutrophication of this pond was in progressed more. Furthermore, Tsunami with the Great East Japan Earthquake in 2011 made a drastic change of ecosystem structure of this pond, that is, the water quality was improved and Ruppia maritima which is endangered spices water plant has become observed. The biodiversity became rich with increase of zooplankton and the food web became complexified.

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 A method for safe use of large amounts of debris sludge yielded after a disaster was established. Since the debris sludge consists of colloidal organic matter, it is thought that malodorous gases are greatly generated by the decomposition of the organic matter. The debris sludge was comprised of a high content of colloidal organic matter. This is because, the colloidal organic matter adheres easily to silt and clay particles. It has been pointed out that organic substances can be classified based on the ignition behavior of the organic substances, i.e. unstable substances burn at low temperature (less than 350 degree Celsius) and humic substances burn at high temperature (370-600 degree Celsius). In this study, a method based on ignition behavior is proposed to identify the debris sludge which leads to a high risk of malodorous gas generation. Furthermore, a method for utilization of granulated coal ash is also proposed to suppress the generation of malodorous gases.

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 The ecosystem in Miyako Bay was greatly damaged during the tsunami generated by the "2011 Tohoku Earthquake off the Pacific coast". Topographical features of tidal flats and shallows were considerably changed, and large quantities of seagrass and seaweed disappeared. To provide basic background information for a future restoration of eelgrass (Zostera marina) in the bay, we undertook a study of current sediment conditions. Field measurements were carried out at the head of the bay in February and October, 2012. Sediments were collected at stations where Zostera marina had grown prior to the tsunami. Using entropy analysis, we grouped sediments according to particle-size distributions. The head of the bay was divided into three zones on the basis of suitability for Zostera marina. Taking into account the characteristics of each zone, we proposed future monitoring plans.

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 To protect oneself from a huge tsunami occurred along Nankai-trough, it is important to understand the residents' evacuation in Wakayama prefecture given a major tsunami warning in 2011 Tohoku earthquake tsunami. A questionnaire survey was undertaken for residents' evacuation against tsunami in Kushimoto town. As the result, it turned out that the residents of about 30% evacuated, and the main residents evacuated have lived to near the beach and low land of less than 3 m above the MSL. Residents' tsunami experience has influenced against the evacuation, that is there is strongly conscious of a big shake = tsunami.

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 In this study, a survey by questionnaire was conducted on local government's disaster prevention measures as two years have passed since the tsunami disaster triggered by the Tohoku Region Pacific Coast Earthquake. The survey was conducted in 54 cities and towns in Chiba Prefecture and six cities and towns on the coast of Ibaraki Prefecture. The period for conducting the questionnaire survey was December 2012 through January 2013. In Sotobo, Chiba Prefecture, which suffered extensive damage, about 60 percent of respondents said that they failed to provide appropriate evacuation guidance. This figure is higher than in other areas. This shows that two years after the disaster, there is a difference in emergency planning between areas. Less than 20 percent of respondents in Uchibo and Sotobo said that they were able to put their experience of evacuation drills to good effect. Therefore, it was found that it is necessary to prepare evacuation drills in which residents can actively participate.

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 After the 2011 Tohoku Earthquake tsunami, the disaster mitigation guarding human-life as the first object has become the most important issue. In this paper we carried out tsunami evacuation simulations for the Kesennuma city under two tsunami levels, by changing the evacuate operating method and the time of starting to evacuate. Through the simulations, it was recognized the difficulty of evacuation on elderly people safety, if they start to evaculate within 30min. As increasing cars more than 1000, the successful evacuation ratio becomes less than 40%, which is more danger than by walking evacuation due to the inceasing car traffic jams.

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 Information sharing between the parties at the time of emergency, forms the base of all emergency response. Survey results for the port from interested parties, it was found that the following. Prior determination of information sharing, has contributed greatly to the contact in the early post-disaster. It is effective in emergency to determine a range, a method of the information sharing in normal. On the other hand, future work is a study of the contents, such as the scope of information sharing.

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 Numerical forecasts of weather and oceanography are in common in the field of ship operation, as the improvement of computer science these days. However, their accuracies is still unreliable in some situations. Here, nationwide questionnaire is implemented to make sure the current effectiveness of wave forecast from viewpoint of navigation safety. A couple of weather patterns are revealed as the difficulty of forecast. Moreover, two cases of failed forecast are analyzed with observed and forecasted database. These patterns are caused under the low pressure develops and moves north-easterly. Authors concludes that the backdrop has to be revealed why these weather patterns tend to misforcast in the future.

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 Ship's berthing speed were measured at several major container berths in Japan and in South Asia. Analysis was made on the characteristics of berthing speed with tug boat assistance, thruster use, wind speed, wave height and so on. It is found that the berthing speed is mostly dominated by the berthing manner. Berthing speed obeys log-normal distribution while other three factors obey normal distribution. And coefficient of variance of those three factors are considerably small than that of berthing speed, therefore one can determine partial safety factor only for the berthing speed against the target safety index while the partial safety factor of the other three factors to be 1. 0. Under controlled berthing operation average of berthing speed may be 8 to 9cm/s and coefficient of variance may be 0. 5.

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 This paper describes ship action at 2011 TOHOKU earthquake. About fifty-seven percent ships of tsunami damaged area evacuated at the time of tsunami, and about seventeen percent ships waited in port. And about twenty-six percent ships drifted by tsunami flow. And about forty percent ships damaged by tsunami. This paper also describes the results of investigation about ship action at the time of tsunami. According to the investigation, the relationship of tsunami height between ship damage is arranged concerning each harbor, when coefficient of correlation is taken with tsunami height and ship damage ratio inside the port it was about 0. 83.And it seems that the effective countermeasures about tsunami are, for example, information tool preparedness, and the teaching item for foreign seamen preparedness, and so on.

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 When tsunami attacks in harbors, vessels moored at a wharf may be unable to evacuate. Vessels should prepare for the break of mooring tethers, grounding on a wharf, drift to land areas and the collision with buildings. The present paper describes the tsunami simulation and the motion analysis of moored vessels at a wharf. The chart of the break of mooring tethers was created. The chart shows the relation of wave height and the break of mooring tethers. And the influence of the install more mooring tethers to the break of mooring tethers was considered.

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 Tsunami disasters of floating vessels moored on the quay are complex, such as breaking of the mooring line and then drifting and collision of floatingvessels. There was an examplewhich a mooring tether does not break in the ship moored to the floating pier in the damage of tsunami. It was confirmed in the Miyagi Shiogama port in case of the East Japan great earthquake which occurred on March 11, 2011. In this paper, the objectives are to clarify the effect of reducing mooring tether force in case of that ship is moored to floating pier by using 3D-MPS method and also the advantages of floating pier for fixed mooring quay. In addition, in this paper the authors are discussed the following items: 1) Force of tsunami wave on the pile of floating pier. 2) Response characteristics in various incidence angles.

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 Ocean waves have been drawn to attention as new renewable energy sources. This study focuses on the wave energy around Hokkaido in winter. The authors performed resource modelling using a wave prediction model to investigate distribution and characteristics of wave energy around this area. The greatest wave energy was found around the Cape Erimo and Nemuto with a mean wave power of 10-15 kW/m. Spatial difference of the mean wave power varied with O(100 km) scale in the Pacific Ocean side. At the Japan Sea side, spatial fluctuation of the mean wave power occurred in O(1 km), which was more obvious than the Pacific side because of the geophysical conditions. Relatively large wave energy could also be found at the Japan Sea side depending on the location.

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 The technical development of utilizing natural energy has been conducting since several decade years ago, because the global warming and the sea level rise are realizing to human beings. In order to facilitate the technology of utilizing wave energy, which is one of the natural energy, this study examines the hydraulic performance of wave activated pump system which is arranged in front of the existing vertical breakwater. This system is expected to amplify wave motion even under calm wave conditions, which are sometimes observed in a bay, in order to expand the effective range of waves which can be used for electronic power generation. A series of hydraulic experiment were conducted in this study to investigate the characteristics of wave amplification in the wave activated pump. The effect of a curtain wall-type barrier, which is installed to protect pump system, on wave amplification were also investigated here.

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 Generally, many models for large-scale hydraulic test are made from steel and concrete, because it is necessary for them to have strength and durability. Therefore, construction managements that contain safety, accuracy, workability and process control similar to site construction are needed. Although engineers should have knowledge for both general laboratory experiment and site works of construction, there have been no manuals for construction of large-scale model. This is a case study for the large-scale model construction process based on construction of 1/6. 67 scale model used for wave test of the wave power generation facility.

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 Suitable places for ocean current power generation in the East China Sea and the southern region of Honshu, Japan were ex-amined using the data of current path of the Kuroshio at sea surface and current velocity of the Kuroshio. Therefore, the Tokara Strait is shown to be one of the suitable places for ocean power generation, using the strong Kuroshio current. Moreover, it is found that the Kuroshio flows with a speed greater than 0. 8m/s above 60m depth north of Kuchino-shima and south of Nakano-shima.

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 Among utilization methods of the renewable energies, an offshore wind power is one of them expected to be in a practical use. A project to construct offshore wind power facilities is on-going off Kita-Kusyu City. Unlike the onshore construction, there are many problems to be solved in the offshore construction. In this study, examinations was made on the construction control required throughout the project period, especially by focusing on how to achieve the verticality in offshore installation to meet the requirements given by the wind turbine supplier and what sort of controls are required in order to achieve the safe offshore execution within a limited construction period.

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 This paper describes effects of the projecting walls (PWs) to improvement of the wave energy absorption of oscillating water column (OWC) type wave energy convertors which are fixed on seabed and installed onto an existing breakwater. OWC types are one of a wave energy convertor and wave energy is firstly converted to energy of compressed air. The efficiency could be improved by installing PWs to conventional OWC type convertors. However, reasons of the improvement have not been clarified. The effects of the projecting walls to the efficiency were investigated from series calculations with the method presented in the study. In the investigations, motion behaviors of OWC and water region surrounded by PWs were compared and the reasons were discussed. Besides independently fixed types, variations and effects to the efficiency due to a breakwater were estimated in the paper.

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 This research studies improvement of oscillating water column wave power generation by numerical calculation and experiment on rectification of air flow. Numerical calculation is an extension of CADMAS-SURF. We examinedtheeffect of vortex in the vicinity ofcarten wall on airflow by numerical calculation. We also tested a device rectifying airflow from reciprocating current at nozzle. This device has control valve that opens and shuts with respect to water level in air chamber. We confirmed that this system is able to generate uni-directed airflow.

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 This study is intended to develop a wave energy conversion system as an additional facility of a breakwater. The performance of wave energy conversion system using bottom-hinged pendulum is demonstrated based on hydraulic model experiments. Results show that non-dimensional dinstance has significant effect on output efficiency of the present system. Relative wave height has also influence on output efficiency. Maximum efficiency is confirmed to be about 7. 3% of the energy of incident wave, based on present experiments. Moreover, the proposed system has an influence on reflection coefficient, which depends on its installed position and water depth.

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 A purpose of this study is to develop a Vertical Axis Type Marine Turbine with Variable-Pitch Blades which has high torque and power performance and being able to rotate in low fluid velocity condition. A Variable-Pitch system introduced in this study is developed with reference to Cycloidal propeller. Therefor it can be controlled mechanically for each rotation angle of pitch angle of the blade. In this study, start-up, torque and power efficiency performance of a Vertical Axis Type Marine Turbine with Variable-Pitch Blades are evaluated by using a model of turbine in tank experiment. In addition, the auther thought up a method of controlling blades which is adoptable fluid condition of Japanese ocean and estimated the expected value of energy acquisition this marine turbine in Bisan-Seto for one year. As the result of this study, the start-up, torque, power efficiency performance and the amount of acquired energy were improved by applying variable pitch blades. (Ideal-Variable-Pitch type)

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 A new liquefaction prediction and assessment method considering the randomness of waveforms and duration of seismic motions has been developed. The validity of the proposed method was clarified in light of the past five case histories involving the Central Japan Sea Earthquake, the Kushiro offshore Earthquake, the Southern Hyogo prefecture Earthquake, the Suruga Bay Earthquake, and the 2011 off the Pacific coast of Tohoku Earthquake, Japan. The results demonstrate that the proposed method has improved the capability of the liquefaction prediction and assessment, thus warranting its wider applications to disaster mitigation at port and coastal area.

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 Since many container cranes loading and unloading with vessels were damaged during the 1995 Southern Hyogo Prefecture Earthquake, earthquake-resistant technologies have improved such as introduction of seismic base isolation. The developed cntainer cranes were installed to high earthquake-resistance quays and significantly contribute to maintaining function of container terminal after large earthquakes. A container crane is one of factors supporting curgo handling at ports and its seismic performance must be satisfied integrally with its wharf stracture. Related to seismic performance verification of container cranes, strong-motion earthquake motions are observed at some container cranes of ports to grasp their fundamental vibration characteristics. Strong-motion earthquake records observed at a container crane and pile-supported wharves during the 2011 off the pacific coast of tohoku earthquake are arranged in detail, in order to clarify the seismic properties of container cranes and wharf structuires lying lower.

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 Seismic characteristic of an open type wharf was assesed both by microtremor measurement and two-dimensional earthquake response analysis. It was shown that natural frequencies of an open type wharf estimated by two methods well agreed. Autohrs next studied a simple erthquake resistant design method of an open type wharf using frame model and one dimensional earthquake response analysis considering the applicability to practical design. A setting method of damping coefficient to be used in the simple design method was proposed.

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 Enormous damage occurred to the disaster countermeasures office, the river bridges and the fishery port facilities in Shizugawa, Minamisanriku Town due to the 2011 off the Pacific coast of Tohoku Earthquake (M_w9. 0). To evaluate the performance of structures before the attack of tsunami, it is necessary to estimate strong motions in Shizugawa Area with sufficient accuracy, taking into account site effects. In this study, seismic waveform in Shizugawa Area was estimated based on a super asperity model considering empirical site amplification and phase effects. The estimated seismic waveform will be useful in the detailed study of seismic performance of structures before the attack of tsunami.

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 If a replaced sand base of a breakwater liquefies during an earthquake, the breakwater should subside and may be unabele to keep the level of breakwater to defend the coast region from Tsunami. As compared with the 1995 Hyogoken-nanbu earthquake with such subsidence damages, scenario earthquakes in recent years has long continuation time, and there are many scenario earthquakes which have a larger power spectrum intensity(PSI) used for the index of earthquake motion scale. In this study, shake table tests of a large model in 1g gravitational field were conducted in order to predict the amount of subsidence of the breakwater to such a long continuation earthquake motion. There was significant correlation between the PSI and the amount of subsidence; the larger PSI an input earthquake motion had, the larger subsidence was.

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 This study deals with the influences of occurrence frequency of high waves on estimation of life cycle cost for a breakwater covered with wave-dissipating blocks using Monte Carlo simulation. The life cycle cost is defined as sum of an initial construction cost and a repairing cost of wave-dissipating blocks. In the computation of the life cycle cost, an occurrence frequency of high wave is assumed as once a year and is determined on the basis of statistical characteristics obtained from wave observation data. As analysis results of high waves at four stations in NOWPHAS, the cumulative frequency distribution for annual occurrence numbers of high waves can be approximated by the Poisson distribution. In the computation of the life cycle cost, the random numbers obtained from the Poisson distribution are used to determine the annual occurrence number of high waves. The optimum size of block that minimizes the life cycle cost is same in most cases regardless of the occurrence frequency of high waves, however, the variability of the total repairing cost during the in-service period is different depending on the occurrence frequency.

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 This paper discusses life cycle scenarios of an open-type wharf. A substructure consisting of steel pipe piles of an open-type wharf is dealt with in this paper. Performance degradation of the wharf would be caused by corrosion of steel piles. The load-carrying capacity is calculated by the pushover analysis taking into account corrosion of steel pipe piles. The performance requirements of the wharf subjected to level 1 and level 2 seismic ground motions are the elastic limit in the load-displacement relationship and the maximum horizontal displacement, respectively. Seismic response of the wharf is calculated by using a one mass-spring model where the skeleton curve is modeled by a bilinear load-displacement curve obtained by the pushover analysis. The Monte Carlo simulation is applied for the calculation of the failure probability of the wharf after corrosion occurs in the steel piles where remaining thickness of the piles are varied following the normal distribution. The life cycle costs of four repair scenarios are evaluated in consideration of the failure probability, which concludes the optimal life cycle scenario.

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 This study discusses the influence of various conditions on the optimum maintenance level of composite breakwaters and breakwaters covered with wave dissipating concrete blocks in view of minimum life cycle cost. As the results, it was found that optimum maintenance level depends on wave stability of breakwater, rather than wave condition and loss cost condition. This method can be effectively used for planning maintenance strategy to estimate expected repairing costs of breakwaters.

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 Since port structures are exposed in the severe natural condition, it is difficult to estimate the deterioration of components of port structures frequently. This paper presents the more effective procedure for efficient maintenance of RC deck in open-type wharf. Kriging method, a typical method in geostatistics, was applied in this study to estimate the deterioration of a target RC deck using inspection data such as deterioration degree from visual inspection and concrete chloride ion tested from in-situ samples. The results show that Kriging method is useful to figure out the distribution of concrete chloride ion and to predict the deterioration process.

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 This study aims at proposing the new evaluation method of strength deterioration for silt curtain. As strength deterioration is inevitable for silt curtain and there exist many uncertain factors regarding strength of silt curtain, present design method evaluates stregth deterioration on the very conservative side especially for reuse curtain.
 Authors collected 315 datum on strength deterioration for silt curtain from experiments after construction works and field experiment results. Authors proposed an equation for the evaluation of strength deterioration for silt curtain based on the statistical data analysis.

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 Damage of silt curtain used for pollution control during construction may cause serious environmental problem. Evaluation of strength of silt curtain is very important to prevent damage of silt curtain, however, to date there exists very limited data on the relationship between duration of construction and strength deterioration for silt curtain. In this study, we set silt curtain in sea environment for 13 months and monitored the strength deterioration of silt curtain month by month. Relationship between strength deterioration and hours of sunlight and temperature is also discussed.

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 It can raise frictional force to install rubber mat between concrete blocks with the gravity style stacking structure such as concrete lump block and build upright wave absorbing block. Using rubber mat, the authors suggested a method to improving the earthquake resistance of the structure stacking up blocks. The authors prepared the model of installed the rubber mat between the concrete blocks, and experimented on the vibration for the inspection of the suggestion method. The rubber mat prepared for different five kinds of the hardness. The rubber mat performed a coefficient of friction examination and measured a coefficient of static friction and a dynamic friction. By the result of those experiments, the authors clarified the characteristics of the vibration when rubber mat was installed and were able to confirm the effectiveness of the rubber mat which could improve the earthquake resistance.

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 The extremely huge waves higher than the design waves occur frequently due to the sea level rise and due to big typhoons and the sliding disaster of caisson is increase. In this study, Hydraulic experiments were conducted to verify the applicability to breakwaters with the counter-weight block installed at harbor side of breakwaters which proposed by Mase et al. The experiments were carried out in the constant wave hight and three different wave periods. The sliding distance of the caisson which was reinforced by the counter-weight block was small, therefore it was found that the counter-weight block is effective as reinforcement of breakwaters against accidental waves.

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 Wave-dissipating blocks are widely placed in front of the upright seawalls which face to the open sea. There are many cases that such seawalls suffer from an excessive overtopping due to increasing wave height in recent years and require counter measures. In addition, there are some areas in front of the seawalls where coastal erosion is observed. The counter measures, therefore, need to be less impact on vicinal coastal morphology.
 This study examined counter measures of a wave-dissipating seawall in Fukui port, which is located on a coastal area and suffering from the said problems, by a hydraulic model test in consideration of performance requirements of the seawall. As a result, hydraulic characteristics of the counter measures were confirmed by a quantitative comparison in terms of effectiveness on overtopping reduction behind the seawall, reflected wave reduction in front of the seawall and stability of the wave-dissipating blocks.

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 A field investigation has been carried out to evaluate the damage level of wave-dissipating concrete blocks on the Oyashirazu Coast in Niigata Prefecture. Wave heights on the Oyashirazu Coast for 8 years were estimated by correlating the wave heights at the wave observation station off the Naoetsu Port. The damage levels of concrete blocks were estimated with a stability formula for wave dissipating concrete blocks proposed by Takahashi el al.and compared with the field data. When the mean sea bottom slope is assumed to be 1/20, the agreement between them is fairly good. This result is useful for engineers responsible for maintaining and managing coastal structures.

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 The damage of armor blocks occasionally occurs at the toe of a mound foundation of a breakwater although the block weight is larger than the one calculated by the Hudson equation. This paper aims to elucidate the mechanism in detail by conducting 2D experiment and 2D numerical simulation. By 2D hydraulic model experiments, acceleration of the offshore flow on the block has a high correlation with damage of the armor block. By 2D numerical calculation, the lifting force exerts on the armor block when the flow direction around the block transitions to offshore from onshore, and a large lifting force to act as the weight of a large block.

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 Damage of a structure is accepted if it gives less influence on its performance since 2007 (Guideline for performance design) in Japan. To realize an idea of the guideline in a coastal structures planning, assessment for 'state' and 'degree' of failures becomes essential in advance. This study proposed statistical method to assess a composite breakwater sliding, applying Monte Carlo wave climate simulation method. A concrete method is shown to make clear about a relation between design conditions and a probability that the structure keeps the performance within a servicing period.

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 Two dimensional earthquake response analysis is a standard tool for seismic design of quay walls against the level-two earthquake ground motion. However, the computational load of the method is large.
 This study aims at proposing the simple estimation method for the residual deformation of quay walls considering the effect of liquefaction during earthquake. We conducted 5, 600 cases of two-dimensional earthquake response analyses and studied the correlation among the deformation of quay walls and parameters obtained by the one-dimensional earthquake response analyses. We proposed the simple estimation method and verified the accuracy of the proposed method by using past disaster case histories and actual design examples.

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 This paper discusses the cracking of un-reinforced concrete coastal facilities. Inspection on unreinforced concrete coastal facilities has been conducted to measure crack widths, length and numbers. The inspection data are analyzed based on the statistics analysis and the crack properties are quantitatively evaluated. As the results, it is proposed that a method to predict the extremal value of crack width in the facilities can be estimated with high accuracy only by investigating about 20% of all the spans.

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 Performance characteristics of a single-water-chamber type breakwater have been clarified as compared to that of conventional breakwaters, typically a composite breakwater with concrete block layers. Focusing on the wave reflection as well as the wave transmission due to wave overtopping above the breakwater crown, effectiveness of the water chamber type breakwater was examined extensively from both the experimental and theoretical points of view. In order to improve the stability of the water chamber type breakwater against wave action, a modified water chamber type breakwater filled with concrete blocks in the water chamber was proposed and its performance was examined. In order to get a rough estimation of wave loading on the water chamber type breakwater, numerical analysis based on the damping wave model was employed to predict wave forces on the breakwater.

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 Large-scale (1:1) and small-scale (1:10) experiments were carried out in order to clarify the characteristics of the tensile force acting on the surface of a geosynthetic tube. The observed relative axial tension was higher than the theoretically estimated tension, and the hypothesized inextensibility of the membrane was suspected to be the cause of the difference. Although an apparent increase in axial strain was observed during horizontal and upward deformations of the tube, the strain seemed to become saturated when the horizontal deformation was large. In the small-scale experiment, the tensile force showed some fluctuations that corresponded to the wave attack; other than that, visible deformation was not observed. Desirable safety factors for designing the tensile strength of a geosynthetic tube are discussed based on these findings.

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 The drifting seaweed reaching ashore or inflowing to the harbor often cause a devastation of scenery and an offensive odor to which a countermeasure has been desired. A technology to capture such drifting seaweed has been developed and nearly in a practical use but a problem here is that the captured seaweed need to be collected and disposed by spending cost and time. In this study, a seabed-based structure which has a function to effectively exhaust drifting seaweed, such as the kelp which has settling velocity, out of the area concern was developed and its effectiveness was verified by the hydraulic experiment.

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 The coastal areas of Tohoku was atacced by Tsunami due to the 2011 Off The Pacific Coast of Tohoku Earthquake that occurred on March 11, 2011.There were severe damage to shore protection facilities, dikes, seawalls, and breast wall. Because it was assumed that the tsunami was higher than the external force of the shore protection facilities design, Fisheries Agency conducted the survey of the disaster, the analysis of the external force and a review of the design conditions before the restraction works.
 In this paper, we reducted the situation of damage to facilities and the patterns affected from the results of the "The 2011 emergency survey of the disign conditions of shore protection facilities". Breast wall affected is higher than the percentage of destroyed dikes and seawall. Percentage of affected by the push waves and back waves, the damage of dikes were about the same, the damage of seawall were a high percentage by back wave, and the damage of breast wall were a high percentage by push waves.

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 Many fishing ports were struck by the 2011 off the Pacific coast of Tohoku Earthquake and following tsunami. Observed deformation at quaywalls was brought by both ground motion and tsunami. To divide both effects correctly, seismic response analyses were carried out. In the analysis, ground motion of each sites were estimated using site effect replacement method. As a result, Deformation caused by ground motion and tsunami was separately estimated. The effects of liquefaction due to ground motion were also estimated.

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 Tsunami-induced wave pressure and force acting on an instrumented specimen fronted by macroroughness elements are investigated numerically in terms of the arrangement of the macro-roughness elements. Numerical results show that the arrangement of the macro-roughness elements affects an increase rate of the inundation depth relative to the absence of the specimen, and accordingly exsisting formulae can underestimate the vertical distribution of the maximum wave pressure acting on the specimen. This suggests that it is essential to consider the arrangement of the macro-roughness elements when evaluating the wave pressure. Furthermore, it is found that the the change in the tsunami force acting on the specimen with the alongshore spacing of the macro-roughness elements constant can be evaluated by the momentum of the water mass in the absence of the specimen.

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 Laboratory experiments on tsunami wave force were carried out to investigate a drag force acting on a horizontal pipeline and oil tanks. The vertical distributions of model tsunami wave force were measured at the location from the seawall. The maximum wave forces were found to be occurred at the location just behind where waves begin to break. Wave forces were estimated by using the CADMAS-SURF and compared with the experimental results. The agreement between them is fairly good when the drag coefficient is assumed to be 0.7 to 1.0.

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