Along the 3000 km coast of the Spanish Mediterranean there are about 150 marina facilities. The coast between Gibraltar and Cabo de San Antonio is called Costa del Sol (the Sun Coast) and Costa Blanca (the White Coast).
The author visited 44 marinas in these areas and reported the characteristics of marina development and the recreational boating found. The quality and quantity of the competitive supply of marina facilities are adequately balanced in these areas.

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The main object of this research settles on the improvement plans for environment on a coral sea area around Awa-Takegashima underwater park in The East Shikoku distinct. Many people have pointed out the decrease and the change on the coral around this park in the past thirty years since 1972, when this sea area was designated for one of the underwater parks. We investigated the social, the nature and the stream conditions around this sea area.

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The Omori hometown shore project, from the first in 1981, was planned for constructing a sewage disposal plant and a park. But, many citizens opposed this plan. They required obliged to be thought over this plan. For more then 20 years through deliberations with the fishery societies, conservation groups and the persons concerned, the present plan has agreed. The construction plan was changed into restoration of original environment in Omori shore by constructing tidal flat, sand shore, and. shore protections by stacking stones. After started this project, the persons concerned had various opinions. Several meetings were held in order to disclose and deliberate upon the problems in concerning with this project. NPO supervised the environments in the independent position during construction periods. These positive information disclosures and citizen's participation systems brought smooth construction promotion.

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This paper is considered about formation of the organization for promoting exchange between urban residents and fishing community by investigation of three practice areas. Three investigation areas are Ine-cho, Shibetu-cho and Yuki-cho where the contents of activity are different.
The results of the study are as follows: Ine-cho is in an initial stage. Its subject is in cooperation of each organization in an area. Shibetu-cho is in a fullness time. Its subject is strengthening of the organization which performs staff training and planned development. Yuki-cho is an extended stage. Its subject is the function and role towards the community improvement by the organization outside an area (The cheering party for an area in outside).

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In recent years, the number of the sight-seeing which includes experience fisherperson's life has increased. Exchange between urban residents and fishing community, such as experience activities is expected as means of building a vitality of a region. The purpose of this study is clarifying the subject of advancing experience activities in fishing village. The investigation is contained the questionnaire analysis of the organization that is performing experience activities in coast.
The subjects of advancing experience activities can be summarized as follows: A fully worked out plan. It does not depend on volunteer for many times. A parson is secured who assume experience activity.The substantial activity organization is made.

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In harbors, the sheltered water basin from wave actions is usually required for berthing ships safely to piers. However, the construction of harbor breakwaters for the basin tranquility may be responsible for reducing seawater circulations in the basin and often causes the difficulty of seawater exchange between the inside and outside harbor.
In this study, in order to improve the seawater quality in a harbor, a new type of reflection wave dissipater from piers and sea walls is developed. Especially, for activating the aeration of basin water, we have used wave interaction process with the dissipater to activate the aeration of the basin water. The piston mode wave resonance in the water chamber of the dissipater is a main driving force to activate the entrapment and diffusion of air bubbles to the water. Both the functions of wave energy dissipation and activation of the aeration by a new dissipater are examined experimentally and theoretically.

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Littoral landform, temperature and moisture condition are studied in relation to the habitat of Cicindela lewisi juveniles at Okinosu beach, Tokushima prefecture, where artificial beach is planned for alternate its habitat. This paper describes environmental condition of existing juveniles habitat which locate narrow line near the coastline of HWL, and proposes required environmental targets to make alternate habitat in the artificial beach and key terms of reference to confirm juveniles ecesis in the process of adaptive management.

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Three artificial reefs have been built off the shore of Waita in Kitakyusyu, Fukuoka Prefecture, which is to prevent the erosion of the seashore. During the construction, we started researching on the effects of these artificial reefs for the sands stability and the nursery ground, continuing for four years through its completion.
Although there are natural seaweed beds around this sea area, we were unable to observe any seaweed on the artificial reefs when two of them had been set up. Right after the third reef was placed, however, seaweed (Sargassum) beds began to spread.
Therefore, we examined if there was any correlation between changes of nearshore currents caused by the third one and the growth of seaweed on natural or artificial reefs. As a result, we suggest that the changes of currents improved the growth of seaweed beds.

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Environmental risk assessments will be necessary in the near future when every facility that may exhaust pollutants such as a chemical plant or a waste disposal plant is constructed. The puff-plume model is commonly used for the environmental assessments of atmospheric pollutions in Japan. Although the puff-plume model is applicable to calculating pollutants concentration in relatively simple wind fields, we have to examine whether it satisfies requirements of the risk assessment model. The aim of this study is to verify the model using common weather conditions simulated by a three dimensional atmospheric model. Pollutants concentrations were calculated by the puff-plume model and compared to those by three-dimensional simulations. The puff-plume model doesn't calculate pollutants concentrations accurately in the bay area under a weather condition that sea and land breeze is rising.

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Yatsu Higata is one of the most significant remaining tidal flats in Japan. In recent years, Yatsu Higata has witnessed an extraordinary growth of Ulva sp. algae. This paper explores the possible origins of Ulva sp. in Tokyo Bay and describes field studies intended to explore the relationship between the Ulva sp. found in Yatsu Higata and in Tokyo Bay. As a result, the Ulva sp. flourishes in Yatsu Higata, due to the ready supply of nutrient runoff supplied by the Yatsu River. The movement of Ulva sp. from the flats to beyond may help reduce the pollutant load on Tokyo Bay while simultaneously helping to preserve the Yatsu Higata environment.

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An evaluation model on closed water ecosystems coupled with the benthic system was examined. The model was composed of 7 pelagic compartments (phytoplankton, zooplankton, ammonium, nitrate, phosphate, particulate organic matters and dissolved oxygen) and an elaborative sediment flux model that represents the benthic system including microalgal functions. The model showed contrasting dynamics depending on water depth regimes. 1) In the shallow lake model (2m), benthic microalgae grew rapidly and consumed nutrients in the bottom layer. 2) In the deep lake model (4 m) in which benthic microalgae rarely grew, nutrients from the sediment triggered phytoplankton outbreaks in the pelagic layer, and the light availability to benthic microalgae was severely limited. These results suggest the impor ance of light attenuation associated with depth and turbidity. This model could highlight the role ofbenthic-pelagic couplings in closed waters

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Recently, it has been necessary the purification of basin water in port and harbor for utilizations, such as live fish preservation facilities and amenity space. Therefore, various types of water-exchange breakwater by wave energy, tidal current and sea level exchange have been developed. The authorsdeveloped a wave dissipating caisson breakwater having a function of seawater exchange. This caissonis a permeable slit caisson with a submerged vertical plate in a water chamber, and generates a one-way flow from offshore to harbor.
In this paper, through the field investigation, we proved the water inlet ability of this water-exchange breakwater that was constructed in MISAKI fishing port, and compared the result of the hydraulic model test with the result of the field investigation.

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Seawater exchange is being considered as a measure against deterioration of water quality and freezing, which are becoming problems in harbors and fishing ports. It is therefore desirable to develop aseawater exchange system with low running cost to put these systems into practical use.
At the same time, development and use of new energy sources such as renewable energy have become much more common in recent years due to concerns about the global environment. Hydrogen is a clean energy source that can replace fossil fuels. Metal hydride (MH) has been studied as a method for storage of hydrogen. The MH actuator is being developed as a method for directory obtaining a mechanical force using hydrogen pressure generated by a temperature difference applied to a MH.
In this study, seawater exchange system was produced experimentally using a MH. This system could be applied to practicaluse as a sea water exchange.

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Long term environmental monitoring at Tokyo bay entrance is important in order to control the current and water quality in Tokyo bay. We installed the environment observation system in a ferry boat which crosses the Tokyo bay mouth. The system is composed of ADCP (Acoustic Doppler Current Profiler), water quality and meteorological observation system.
In this paper, the property of this observation system and the obtained data are shown.

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Development in the coastal zone was focused on from functional aspects such as utilization and protection. In recent years, responding to the social demand for nature conservation, numerous projects have been carried out, seeking ways of coexistence with nature. This report presents an outline of the planning, design, construction and monitoring of such an experiment on how breakwaters can be harmonized with nature. Three types of breakwaters were constructed at Maruyama Fishing Port in Hyogo prefecture to compensate for the loss of seaweed beds due to reclamation. In a survey carried out for three years after construction, the situation was judged to have reached mid succession as the number of species and the diversity index of the seaweeds and phytal animals had increased.

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In order to using scallop shells of a fishery by-product effectively for the back-fill material of aquay, we investigated the internal friction angle of the sand mixed crashed scallop shells by consolidated-drained tri-axial compression test. The following conclusion can be obtained from this study. When the maximum grain size of crashed shell and the rate of shell mixture decreased, the mass of unit volume and the internal friction angle increased, and it turns out that the crush of shell itselfdecreased. It has checked that the sand mixed crashed scallop shells is applicable to back-fill material to some extent.

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Recently, nori culture in the Ariake Sea is a poor harvest. It is known that one of the factor of the poor harvest of nori culture is a shortage of nutrients required for growth of nori. Two areas on mud flat in the Ariake Sea, where one area is tilled with a mud flat move machine and another area is not tilled with it, were set up for investigation sites in this study. These data of the water quality, the sediment, and the release from sediment of two areas were compared. Consequently, it turnsout that the release of NH₄-N and PO₄-P from the sediment is promoted by the tilling with a mud flatmove machine. Therefore, the tilling with a mud flat move machine was considered to be an effective method as the supply of the nutrient salts at the time of nori culture.

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We conducted two sets of the experiments on coral recruitment by in situ mass culture, transportation, and release of reef-building coral larvae in Okinawa, Japan in 2002 and 2003. Gametes and embryoswere collected from slick on the sea surface and cultured in floating culture ponds at Akajima untilthe larvae were competent to settle onto a substratum. About 2 and 4 million larvae were transportedby boat to a seeding experimental station at Naha Port, a distance of 50 km east of Akajima in 2002 and 2003 respectively. Divers released the larvae over concrete blocks surrounded by nylon mesh enclosures. The number of polyps settling on the blocks was monitored regularly and compared with a control block outside the enclosures. In 2003, we investigated density of the larvae at each process andprepared hollowed concrete blocks to enhance larval recruitment. As the result, the number of polypsin 2003 increased 2 to 3 times of the 2002. Although it needs improvement, this restoration technology is considered to have reach a satisfactory condition.

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In Hokkaido, more than 30 semi-closed water areas exist, and aquaculture has been performed in many of those water areas. Since the semi-closed water area connected to open sea by narrow mouth, the area is suitable for the aquaculture of scallops, oysters, and other marine products. However the water quality in semi-closed water area has the danger of getting worse quickly with change of surrounding environment. For the permanent use for the aquaculture, the maintenance of the water quality is needed. As one of the water quality preservation measures, promotion of the water exchange is mentioned. Although the aquaculture facility densely installed in the water area is one factor that worsenswater exchange, the flow analysis and evaluation of the amount of water exchange in considering influence of the aquaculture facility has not been performed. In this paper, the influence of aquaculture facility to water exchange clarified by the flow analysis which set up the fluid resistance of thefacility obtained by experiment is described.

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Habitation condition of the hermit crabs in the vicinity of the seawall at an artificial beach was investigated at Kemigawa beach in Tokyo Bay. This beach is surrounded by two curved groins at south and north ends. At the northern side of the south groin, where is located inside the wave shadow zoneof the curved groin, dense habitat of hermit crabs were discovered near the mean sea level. The causes were studied by the numerical simulation of waves and nearshore currents as well as field observations. Three main causes were pointed out. At this area, direct sunshine is cut off by the seawall in summer. There exists a wave calm zone due to the wave sheltering effect of thegroin and wave induced currents always flow from outside to inside of the wave shadow zone, gathering much plankton.

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Artificial beaches are usually used throughout the year, therefore the maintenance of those beaches are very important. Inagenohama in Chiba prefecture was built as the first artificial beach in Japan. So various maintenance problems have appeared there, in particular, beach garbage is one of the most important problems. This paper investigate the beach garbage characteristics, and analyzed the good beach environment for the users.

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Contingent Valuation Method (CVM) is a typical method for us to measure the benefit and/or cost of goods having no market, such as tidal flats and shallow water area. CVM has several types for gettinganswers. Among them, the referendum type is seemed having least biases in the estimation. But, the payment card type is rather preferred to the referendum type in business practices, because the referendum type requires many data for reliable estimation. Using the case of promotion of tidal flat andshallow water area in Mikawa Bay, the authors analyzed the statistical reliability of the payment card type CVM for the purpose of enhancing usability of the method.
The author estimated WTP median and compared the WTP median and its precision estimated by the density distribution curve with those by the cumulative distribution curve. Significant difference of WTP medians was not observed. There was, however, significant difference in the precisions of WTP median. Therefore, the author formulated an error rate function by the sample number in the case of using the density distribution curve.

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Heiwajima Tidal Flat was improved and developed by means of moving former tidal flat in August at 2003. As it was concerned that the movement had severe damage to benthos in it, we took care of their environmental condition. So, we moved surface layer of the former tidal flat to its surface. Furthermore, we had ecological and soil survey on the tidal flat several times before and after its construction. In ecological survey, it was found that the number of benthos in it has been rising and recovered former tidal flat within 6 months. In soil survey, its soil formation was becoming similar to former tidal flat. As the result, this tidal flat was becoming similar to former tidal flat.

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This study presents a new methodology to evaluate the degree of physical environment and bio-chemical environment at the specific coastal sites. We carried questionnaire surveys to determine weighting factors of coastal environmental elements, which constitute natural environment of the coastal zone, and field studies to measure values of these elements at 12 major coastal sites along the Kyushu.By using the acquired weighting factors and values of the coastal environmental elements, two evaluation techniques are proposed: a relative evaluation technique with average values of all the sites as base values and a point-wise evaluation technique with certain criterion for each elements. The proposed methodology provide a useful tool to evaluate natural environmental characteristics of the coast zone.

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This paper investigates into the type of growth environment required for the tropical seagrass of Okinawa sea area. Due to the open geographical location of Okinawa sea area, the tropical seagrass beds in this area are often subject to typhoon waves and strong currents. These physical factors are known to alter the seafloor structure, and confirmed that it leads to the disappearance of the seagrass beds and limitation of their growth. In order to determine the ideal growth environment for the seagrass, a new parameter, which measures the depth of seafloor sand layer was introduced.

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Reviewing past examples of eco-friendly technologies, as well as findings from field surveys, we applied those results for improvement works of fishing port facilities in Okinawa.
In regard to coral reservation and restoration for the project of constructing outskirt structures such as breakwaters, it is advisable to employ the existing methods of transplanting or relocating coral reefs, or the methods expediting coral larvae settlement by uneven-surfaces on substrate. The newly conducted field survey of the waterway in Tonoshiro Fishing Port indicates that adopting gently inclined slopes in waterways is considered to be a feasible option for coral reestablishment and it is desirable to install stable substrata on the bottom of waterways. Regarding to mangrove restoration on and around port structures, it is necessary to take into consideration the fact that the settlement and growth of seedlings can be affected by waves.

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The influences of many factors on the accuracy of the damage prediction have been evaluated for a two-dimensional effective stress analysis program code: FLIP. Although many improved numerical models for more precise prediction have been proposed, the influences of those improved models varied with the difference of structural type and situation. This study was carried out to verify th accuracy ofthe seismic damage estimation for various types of quay wall on the liquefiable ground by the FLIP code with all these improved models simultaneously.
Through the seismic damage analyses of sheet pilequaywall, gravity quaywall and piled pier constructed on the liquefiable ground, it was observed that the improved models work well not only for the structure in which the conventional model had worked well, but also for the structure in which the conventional model cannot work.

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An advanced finite element analysis for liquefaction process is carried out in order to simulate pore pressure accumulation in seabed around a pipeline due to horizontal cyclic loading. Pore pressure build up response in seabed due to horizontal cyclic loading of a pipeline is numerically investigated through some examples from the viewpoint of the horizontal cyclic displacement and the stiffness of joint element between the pipeline and seabed. The displacement behavior of the pipeline, the effective stress path and the shear stress-strain relationship in the seabed around the pipeline are obtained by this numerical analysis. Pore pressure build up response greatly depends on not only the horizontal cyclic displacement but also the stiffness of joint element.

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In this research, the “floating beach” which combines the floating breakwater and a pump function was developed. The floating beach is constituted from the board prolonged in the shape of radiation onthe slope of a cone form at equal intervals, the skirt attached at the equipment lower part, and thehose for water supply extended in the lower part. In phenomenon the movement energy of a wave is dissipated by loss of that an incidence wave converges to equipment, and wave breaking and wave overtopping, and the dissipation by the skirt. Moreover, it is equipment which can send water to a lower layer through the hose with which the wave which ascended the inclination board flowed into the hole of the equipment central part, and was extended below by making the grade out of which the top part of the equipment central part comes for a while from the water surface float. This research examined the wave absorbing characteristic at the time of installing a floating beach model in straight line arrangement and alternate arrangement, and the water supply characteristic depended on floating beach.

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This paper reports drawing up a shore protection plan reflecting the opinions of local residents in the southwest-coast of Ise Bay. In the meeting that two mayors, a town headman and scholars are member for discussion about shore protection in the coast, it was decided to organize the regional informal gathering for discussion about shore protection in three areas, Matsuzaka City, Meiwa Town and Ise City as opinion hearing method of the regional residents in June, 2002. Several ideas that were obtained from the opinion exchange of the meeting with the regional informal gathering were reflectedto the shore protection plan in the coast.

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To explore the effective countermeasures against erosion of beaches, shoaling of harbors and blocking of river mouths, it is essential to acquire information on the direction and the volume of net sediment movement. However, much difficulty has encountered in field measurements of these physical quantities. So these physical quantities are usually estimated by analyzing data of topographic changes.
This study will present a new simple scheme for estimation of the spatial distribution of net sediment transport rate on the basis of bathymetric survey data. The present method facilitates practical applications.

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In order to recover sandy beach, an improvement method of gently sloping revetment with dangerous exposed slippery toe was proposed by the nourishment of gravels. Ishikawa coast was selected as an example of the study. On this beach, gently sloping revetment has been built in front of the existing seawall, resulting in disappearance of sandy beach. Protruded gently sloping revetment was damaged by waves. The effect and stability of beach nourishment were predicted by the contour line change model. Their effectiveness was confirmed by numerical simulations.

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Beach nourishment is now the principal option for shore protection in some countries, such as the USA and The Netherlands, and it is being increasingly employed in other countries, particularly in Western Europe. Few studies have evaluated the biological aspects, especially the benefits that result from the widened beach. This paper summarizes the state of the art on biological implications of beach nourishment operations in the USA to identify the biological tradeoffs involved in these operations and steps that should be taken to maximize beneficial uses of beach fill.

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In recent years, coastal erosion has emerged as a nationwide problem. Toward comprehensive sediment manegement that promotes coastal conservation, the mechanism of wide-area littoral drift needs to be understood.Research on sea sand drift has thus far targeted relatively shallow sea areas, such as the surf zone. For wide-area sediment management, however, a study should be extended to include the role of grain in sand drift and to include sand drift in deep-sea area. As part of this research, an field survey was conducted in the Ishikari coastal deep-area in winter, when significant wave height occur. As a result of this field survey, characteristics of flow and littoral drift were found.

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Rubble mound breakwater is permeable to wave, current and sediment sand. In order to reduce inflow of sediment sand through a rubble mound breakwater, impermeable countermeasures such as sheet piles etc. have been occasionally constructed behind the breakwater inside harbors at thermal or nuclear power plant sites. For evaluation on the workability of such countermeasures against transmitted sediment sand, it is necessary to elucidate transmission mechanism of sand sediment through rubble mound breakwater. In this paper, at first, characteristics of overtopping and transmitted sediment sand through rubble mound breakwater caused by waves, is investigated in detail experimentally. Based on experimental results, rates of overtopping and transmitted sediment sand are modeled. Next, these sediment models are introduced into 3-D beach deformation numerical model. This new numerical model is applied to a field area of the sea around the harbor at the Higashidori nuclear power plant site and verified by field data.

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The beach change in the neighborhoods of the breakwater is re-considered by using results of the bottom sounding and the wave observation which have been surveyed on the new port of Ishikari Bay.
As results, the beach change is influenced by the breaking water depth, the breaking wave height, and the equilibrium beach profile.

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The purpose of this study is to develop a prediction model of beach evolution using a quasi-3D current model that can predict the shoreline changes. In this study, the 3D morphodynamic model with shoreline changes proposed by Kuroiwa et al.(2004) were modified. The modified model was applied to several model tests of the beach evolution around detached breakwaters in order to examine the performance of the 3D morphodynamic model. Furthermore, the application to beach evolution around a groin and pocket beach was carried out and then the applicability of the modified model was discussed.

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Beach profile change has been investigated in relation to velocity field inside and outside of permeable beach. Velocity field on shore and swash zone has been obtained by conducting numerical simulations and model experiments. In the experiments, water surface change has been measured using run-up gage covered with finewire mesh and compared to verify the numerical simulation results. Infiltration flow has been found to play an important role on sediment transport. It is also revealed that sediment transport and formation process of gravel beach can be well explained by considering of kinetics on beach.

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This study is concerned with the prediction method of 3D beach evolution in the long-and short term. As the first step, a 3D morphodynamic model, Q3D-CAM (Coastal Area Model based on Quasi-3D nearshore current model), is proposed. First, in order to investigate the characteristics of the presented model, model tests associated with a detached breakwater were carried out. Secondly, the applicability of the model to the prediction of sand bar movement in the short term was examined, and also the model was applied to the 3D beach evolution around a port in the field. Finally, the prediction method in the short-and long-term was discussed.

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Disappearance of sandy beach caused by the excess development of coastal forest was investigated along the Kujyukuri coast facing the Pacific Ocean. Since World War II, coastal forest has been created to prevent damages due to wind blown sand. However, coastal forest zone was excessively widened in the natural sand dune areasas well as the construction of protection facilities of themselves such as an earth dike, increasing potential against beach erosion. Furthermore beach erosion took place due to the decrease in longshore sand supply. Thus sandy beach of Kujyukuri coast has narrowed by these causes.

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Topographic changes of the river mouth bar and terrace of the Sagami River were investigated through field observations and numerical analysis of waves and nearshore currents. The river mouth bar of the Sagami River has retreated and deformed largely, resulting in the sand deposition to the navigation channel of Hiratsuka fishing port. In order to improve this condition, fundamental mechanism of sand movement around the terrace off the mouth was investigated. Sand deposition into the navigation channel was accelerated by the longshore sand transport along the marginal line of the terrace.

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A method to control sediment transport by using DRIM has been examined through three dimensional movable bed experiments and numerical simulations. DRIM is short for the Distorted Ripple Mat', the surface profile of which is of distorted sinusoidal curve, and can control sediment transport in one direction under waves. The effective layout of DRIM installation is examined through movable bed experiments. In addition, the numerical model is improved to reproduce the phenomenon observed in the experiments. As the result of the examinations, it is confirmed that the layout of DRIM where the additional unit (called offshore-tail) is attached is quite effective to increase the effect of controlling sediment transport.

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Formative mechanism of iron sand layer on the foreshore of the eroded beach was investigated through field observation and numerical simulation considering density difference of the bed materials. Field observation was carried out at the Ohga coast in Tateyama Bay. On this coast, a river mouth jetty was built, resulting in the formation of wave shadow zone. Sand was transported by longshore sand transport from outside to inside the wave shadow zone. Eroded beach was covered by the black sand containing much iron sand. Accumulation mechanism was predicted by the one-line model of beach changes, considering density difference of the bed materials. Observed phenomenon was well explained by this model.

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Beach changes of the Akiya coast located in the western part of Miura Peninsula was investigated through field observations, analysis of aerial photographs and numerical simulation using the contour line change model. One of the causes of beach erosion is due to the longshore sand movement associated with the formation ofwave shadow zone of the breakwater of Kuruwa fishing port. The other main cause is the loss of sand due to the northward longshore sand transport, overflowing the foot of Chojagasaki Point located at the north end of the coastlineduring rough wave conditions.

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At Kemigawa beach in Chiba Prefecture, the central part of the artificial beach has been eroded due to the wave sheltering effect of the curved groins built at both ends of the beach. As a countermeasure, gently sloping revetment was built in front of the existing seawall exposed in the eroded area. This accelerated loss of sandy beach due to the burying under the concrete slope, and the toe of the gently sloping revetment became slippery because of the attachment of marine organisms, disturbing usage of the coast. These situations were analyzed by field observation and numerical model.

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At Pengambengan, facing Bali Strait in Bali, Indonesia, predominant northward longshore sand transport was obstructed by the construction of fishing port, resulting in severe sand deposition inside the fishing port as well as downcoast erosion. Field observations were carried out two times in May 5 and August 8, 2002. On the downcoast, seawall fell down and scarp was formed continuously due to severe erosion. In order to improve the present condition, it is required to take fundamental measures such as sand bypassing instead of local optimization of the eroded coast using structural defence.

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Coastal zones are precious environment for the small island countries in the South Pacific. The coastal zones consist of sandy beaches, coral reefs and mangroves, which have been kept natural for a long time. However, since around 1960, coastal erosion has become apparent, and today it is a prevailing problem in many islands. In this paper, the present situation of costal erosion is presented based on field and literature surveys for Fiji, Samoa, Tuvalu, Kiribati, etc. There are very few places where modernc oastal engineering was applied to design and construction of coastal protection measures such as seawalls. A major problem is; lack of scientific and technical knowledge for erosion, fragile materials used, lack of appropriate design of coastal structure, and poor financial, institutional and technological ability of governments of the island countries.

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Naha immersed tunnel will cross under the port entrance of the Naha wharf, Okinawa, where large liner ships are in service. Fluid power caused by the large vessel was expected to influence strongly against the stability of the tunnel element during construction. In this report, the stability of the element is investigated through three-dimensional numerical simulation, in which speed of the large vessel is assumed to be constant. It is confirmed from the simulation that a large up-lift force is generated by the large vessel when it passes above the element, and that increase of navigation speed reduces the stability of the element against sliding.

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Two routes of north Yamatoguchi and southern Touguchi are fixed in the Naha harbor.However, a Yamatoguchi route has narrow Entry-into-port part to the weather and billow conditions, and is difficult to navigate--etc.--since there is a problem on use, most of large vessels use Touguchi. On the other hand, it is expected by the deployment to the north Urasoeh ead area that the importance of a Yamatoguchi route will increasei ncreasingly from now on. Then, it is necessary to regard a Yamatoguchi route as the main route of the Naha harbor, and to fix as a route which a large vessel tends to use. This examination reports what carried out the navigation simulation in order to verify the form of a route, andt he safety of the navigation about arrangement ef a breakwater, when a vessel uses a Yamatoguchi route.

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This report describes repair methods applied to the bridge piers (Nos.P7&P8) damaged due to chloride induced corrosion together with seismic strengthening applied in 2001-2002, It is required that economical concrete mixes and construction methods, which are applicable to the concrete structures damaged due to chloride induced corrosion under any climaticenvironment, will be developed.(selection of section recovery material, deal with change of concrete, )

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