Kamata (1967), Kondo and others (2003) researched particle size composition of sea bottom substrates in the Ariake Sea and Shimabara Bay, which are located in the west part of Kyushu, Japan, and showed clearly that the depositional environment of this area is divided into five deposit types. Later, Akimoto and others (2006) clarified the existence of an area containing mud in the eastern Shimabara Bay and off the river mouth of the Shirakawa River, and analyzed the vertical distribution of the mud content. In our research, bottom sediment samples were extracted with a sediment sampler from both the Ariake Sea and Shimabara Bay in April 2002 for further analysis, and we determined the spatiotemporal distribution of their contents. Which was about 1 week before the opening of the gate of Isahaya bay dike, so in our study we are only considering the previous depositional environment of this area.

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 To monitor the depletion of dissolved oxygen in the hypolimnion of the lakeand the inherent increase of nitrogen and phosphorus from the bottom sediment, the Kagoshima Prefectural Institute for Environmental Research and Public Health periodically conducts research to check the further progress of eutrophication in the lake. However, there are few reports about the chemical analysis of the bottom sediment. For this reason, the authors of this study have intended to clarify the seasonal changes in the sulfide concentration of the sediment, accompanied with the depletion of dissolved oxygen, which is one of the chemical indicators of sediment condition. Sulfide concentration had a maximum at the end of the stratification period, while it decreased during the circulation period. These results suggested the possibility of an increase in the sulfide concentration of the sediment, followed by poor vertical mixing of the water, which is a consequence of the advance of global warming in recent years.

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 This paper describes the estimation of sediment discharge volume and the characteristics of sediment deposition in the Niigata West Port. There is serious problem of siltation in the port. In flood time, by considering the influence of the flow rate adjusting relations and hysteresis were calculated inflow sediment accurately. By comparison with the amount of dredged volume and the observed sounding data, the characteristics and accuracy of estimated sediment discharge volume are investigated. And the mathematical model of sediment transport is developed by using POM in order to consider the sediment transport, erosion and deposition in the Niigata West Port. To match the water quality and flow regimes observed, I went the sensitivity adjustment of parameters. And I examined the deposition characteristics and transport of sediment inflow and water quality of Port in flood time. From the results, I found the seasonal variations of sediment discharge volume. And I found the difference of characteristics of deposition rate in the harbor when the river discharge is flood or normal.

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 Dependence on salinity of settling rates of estuarine suspended sediment (The Chikugo River) and coastal suspended sediment (Ariake sea sediment) were studied. Two sediment samples had same mode particle size of the fine particles. As a result of the study, we clarified that the estuarine suspended sediment settled faster than the coastal sediment in freshwater but they had almost same settling rate in the sea water. The estuarine sediment had more amount of EPS. We concluded that the sediment had much faster settling rate under fresh water condition because EPS bonded clay particles and silt particles.

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 Wando is a semi-closed water area whose hydraulic characteristic is different from that of the main river. It served as spawning place and nursery ground of fish juveniles. In this study, field observations were carried out to understand physical conditions of Wando. Study site is at the right bank of the Kakogawa River mouth. As a result, the difference of the amount of deposit and its vertical distribution between Wand and the main stream are clarified. Moreover, the decrement effect of waves by vegetation is also confirmed.

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 This study was conducted to elucidate characteristics of sediment transport in Amitori Bay, Iriomote Island, Japan, and to assess meteorological disturbances and river discharge from the perspective of numerical analysis. Wind speed, wind direction, inflow rate from rivers, and other factors were observed to provide input data for numerical models. Reproduction of coastal currents in Amitori Bay under various meteorological conditions was done using an ocean current model: CCM. Characteristics of sediment transports were examined using particle tracking analysis. Results show that the sediment transport distributions are strongly influenced by the wind direction and the river plume during flooding.

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 The influence of saturated-unsaturated sloped beach on sediment transport in swash zone is investigated experimentally and numerically. The movement of fluorescent sand on seabed and the orbit of fluorescent paint injected into sandy beach are measured in bore wave experiments. As the result, the uplift seepage flow leads to the activation of sediment transport in the direction of runup and backwash under the saturated condition. The numerical modelling simulates the interacting runup wave motion and groundwater flow. The tractive force under the influence of seepage is quantified through a permeable Shields parameter. The results of prediction are in good qualitative agreement with those of experiments.

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 Longshore sand transport on Inage and Makuhari Beaches 5 km distant each other and located in Tokyo Bay was investigated. The direction of longshore sand transport on both beaches was found to be reversed. To investigate this phenomenon, shoreline changes were read from the aerial photographs along with the measurement of longitudinal profiles and the sampling of the beach materials. Furthermore, wave field was calculated using the S-M-B method and longshore sand transport rate on both beaches was estimated. The reversal of the direction of longshore sand transport was triggered due to the change in offshore seabed topography caused by offshore dredging.

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 In order to prevent a diffusion of fluid mud over the seabed with a possibility which contaminents may be included, a containing work has been carried out by covering the area wtih cement treated soils. According to the field investigation result, the mean wet density of the fluid mud was 1.05g/cm³ and its maximum layer thickness was 10mm. For a purpose to find out an optimal execution plan for containing the fluid mud, preliminary laboratory underwater casting test was carried out using several tens types of cement mixed soils. As a result, it was observed that the treated soil A of the density of 1.1g/cm³ with low flowability, cast as first layer with thickness of 10cm, created big voids by itself, in which the fluid mud was contained, and the treated soil B of the density of 1.3g/cm³ with high flowability, cast as second layer with thickness of 10cm, effectively formed the covering layer over the first layer. The laboratory test demonstrated that the fluid mud could be effectively contained into the cement treated soils by using the treated soils A and B. In addition, a field trial test was carried out, which demonstrated that the fluid mud could be effectively contained into the treated soils without diffusion by the abovementioned staged casting of the treated soils A and B.

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 We reclaimed artificial ground made of dredged soil and converter slag by using pipe mixing method for the first time. From the result of the survey, unit weight and short-time strength were useful for predicting sustained strength. Strength of cone and surface wave velocity were useful for assessing ground strength.

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 Lattice-shaped cement treatment by using the deep mixing method has been used as a liquefaction countermeasure. Floating lattice-shaped cement treatment is the method to reduce the improvement depth of it in terms of the economic pursuit of ground improvement. In this study, pseudo-3D analyses were carried out to simulate the seismic behavior of floating lattice-shaped cement treatment in the tests which were conducted for horizontally-layered ground. A Pseudo-3D analysis is the anlytical method modeling 3 dimensional lattice-shaped improvement ground by 2 dimensional analytical method. As a result, by floating lattice-shaped cement treatment, increase of excess pore water pressure of liquefiable soil was fairly constrained, and effectiveness of them was confirmed by the pseudo-3D analyses. Moreover the effect was confirmed in the case of broad range of ground by the analyses.

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 Jet grouting method is known as a measure against liquefaction on the foundation where the fine-grain fraction content in a harbor structure etc. Its problems include high treatment costs and adverse environmental effects of the sludge, which is produced during the cutting of soil. The present study proposes a method for reducing the amount of sludge through its efficient utilization.This method is characterized by recycling of sludge soil. At first, the sludge soil produced by water-jet cutting is collected on the ground. Then, in the recycling process, this sludge soil is mixed with cement and this mixture is filled though the tip of a rod.
 In order to check such a feature, a laboratory experiment and test construction were carried out. The following are the results of the laboratory experiment and the test construction: 1) high-quality soil improved material is produced with a distance of 1 m between nozzle of a high-pressure water jet and the filling outlet without contamination of filling materials, 2) from the viewpoint of non-miscibility with the sludge and repletion of the drilled areas, the desirable flow value is 190±20mm.

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 Intermediate sand layers with high permeability often exist in the ground which has formed by disposing dredged soil. In the case of improving such a ground using the vacuum consolidation method, it is concerned that the consolidation effects would be decreased by sucking considerable seawater through intermediate sand layers. For a purpose to clarify an influence of such intermediate sand layer, two laboratory model tests were carried out. One was a vacuum consolidation test with water suction rate of 2ℓ/min per prefablicated drain and the other was a normal vacuum consolidation test without water supply from the intermediate sand layer. It was observed that the settlement curves of these two cases well agreed. Therefore, it was clarified that the water suction from the intermediate sand layer with its rate of 2ℓ/min does not significantly influence on the performance of vacuum consolidation system.

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 Urban cities in New York and New Jersey were severely damaged by the storm surge in October 2012 induced by Hurricane Sandy, in which the sea level anomaly reached 4 m. The damages included blackout, inundation of underpass tunnels, subways and underground malls, and complete and partial destructions of port and airport facilities, oil refineries, power plants and houses, oil spill incidents. The large sea level anomaly was probably caused by a long fetch, a large shallow water area and wave breaking.

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 On October 29th, 2012, Hurricane Sandy made landfall along the east coast of the United States and generated storm surge in the states of New York and New Jersey. The flooding in New York City caused heavy damage on infrastructures such as an electricity and a subway system. In this paper, the actual situation of this disaster in New York City are summarized based on the results of a field survey and information on public websites and lessons for increasing preparedness in Japanese waterfront area are discussed.

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 The present paper investigates the vulnerability of urban areas in the Mekong Delta to inundation due to seasonal flooding, a phenomenon which is likely to be exacerbated by future sea-level rise. The research reveals that ocean tides predominantly determine water elevation even in an upstream location such as Can Tho City, 80 km inland from the river mouth, and that the river flow causes tidal damping and effectively reduces the energy of the incoming tides. This tidal damping is especially pronounced during the rainy season. Analysis based on the water levels monitored by the Mekong River Commission revealed that the ground near the riverbank of Can Tho City had experienced inundation for a total of 215 hours between July 2009 and June 2010 (2.5 % of the time over a one year period). Assuming three scenarios of SLR of 20, 40, and 60 cm, all within the range of the IPCC AR4's projections, it was found that the duration of inundation will be prolonged from the present percentage of 2.5 % to 6, 13.2, and 23.9% of the year, respectively. It is thus feared that in the future inundation can occur during any season of the year, whereas it is mostly limited to the rainy season under present sea levels. Furthermore, the field survey carried out by the authors shows that inundation reached up to a height of 47 cm above the roads of Can Tho downtown on November 2009. Such flooding can influence daily life, agriculture and traffic in the region and an increase in their frequency and height due to sea-level rise can have negative consequences on the socio-economic conditions of the inhabitants of the delta.

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 Sea level rise and an increase in typhoon intensity are two of the expected consequences from future climate change. In the present work a methodology to change the intensity of tropical cyclones in Japan was developed, which can be used to assess the inundation risk to different areas of the country. An example of how this would affect one of the worst typhoons to hit the Tokyo Bay area in the 20th century was thus developed, highlighting the considerable dangers associated with this event, and how current sea defences could be under danger of failing by the end of the 21st century. The present results show how this level of defences could be inadequate by the end of the 21st century. Possible solutions to this problem involve raising the level of existing defences or increasing the ground level of reclamated area. The cost of possible countermeasures are calculated and are compared with possible economic loss under flooding. The cost is less than 1 % of possible economic loss in Tokyo metropolitan and 6 % in Kanagawa prefecture.

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 Storm surge disasters have frequently occurred at the Ariake Sea coasts in the past. Besides, the innermost area of the Ariake Sea has also large lowlands behind the coastlines. Therefore, once severe storm surge occurs at the innermost area of the Ariake Sea, its damage might be very serious.
 In this study, to understand the characteristics of storm surges along the coast of innermost area, the tidal changes in front of seawalls along 3 different areas were measured for about three months in the summer of 2012. Several typhoons passed through the west sea area of the Kyushu Island during the observation and one of the typhoons caused a relatively large storm surge in the Ariake Sea.
 In addition, to investigate the amplification of storm surge in detail, a storm surge caused by typhoon 1216 was reproduced by a numerical simulation using FVCOM(Finite Volume Coastal Ocean Model). FVCOM was developed by Chen et al. (2003) with unstructured grid system so as to compute tidal currents in complicated inner bays with high accuracy.
 Main findings obtained from observational results and numerical results are as follows:
(1) In the case of T1216, the maximum storm surge at the coast around innermost area increased up to 3times of the maximum storm surge near the mouth of the bay.
(2) The detailed spatial distribution of the amplification factor of storm surge along the coastline in innermost area was clarified.

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 In order to understand characteristics of overflow, we simulated with a wave-simulating numerical flume that sea water flowed over seawall. The numerical flume was CADMAS-SURF, which could simulate water flow in vertical cross-section by using Volume Of Fluid Method. The simulations executed under no-wave condition considerably reproduced flow rates calculated by Honma's fomula (1940). Flow rates under wave condition were higher than under no-wave condition. Its increasing tendency in complete overflow was higher than in submarged overflow. Flow rates over thin wall was higher than over thick wall in complete overflow. In submarged overflow, obious difference between thin wall and thick wall was not observed.

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 We have investigated the sensible heat flux between the water/soil surface and the atmosphere over Yatsu tidal flat using large aperture scintillometer. Diurnal variation of heat fluxes depend not only on the solar insolation but also the water level. Sensible heat flux at Yatsu tidal flat was positive in daytime (83Wm^-2), and daily mean of the sensible heat flux was 1.26MJm^-2day^-1. However, it was relatively smaller than that in a regidential area of Kanto region (about 300Wm^-2, 9.02MJm^-2day^-1)¹⁰⁾. Quadrant analysis of the sensible heat and momentum fluxes revealed that positive heat flux is predominantly accounted by upward motion of heated air which is driven in a soil surface exposed from water.

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 Monitoring of current and water quality were conducted in the summer from 2005 to 2012 in order to reveal the relationship between tidal currents and hypoxia in the inner western part of Ariake Bay. M₂ component were largest in the 10 tidal components, and northern component were larger than eastern component every year from the result of harmonic analysis of bottom layer currents. Tidal current amplitude of M₂ component on 2009 was highest, on 2006 and 2012 lowest in the 9 years. Average dissolved oxygen above the 0.2m sediments on 2006 and 2012 were lowest, on 2009 highest. From the relationship between the tidal currents amplitude of M₂ and stratification, between the tidal current amplitude of M₂ and bottom average dissolved oxygen, estuarine circulation by freshwater input and tidal current variation has also an important role of occurrence of hypoxia in the inner western part of Ariake Bay.

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 The catches of the short-necked clam decrease for sedimentation of the sludge remarkably in the estuary tidal flats of the Hiroshima delta. On the other hand, a steel sheet pile is set up for revetment to prepare for a disaster. The groundwater which flow out underground of the tidal flats was stopped at the landside by a steel sheet pile. And it is assumed that the environment of the tidal flats changes.
 The fishery grounds of the short-necked clam spread a granulated coal ash (GCA) on thickness of 0.3m in the ebb water route of the tidal flats and built it. By laying of the GCA, the biota is turning into the environment where various creatures inhabit. 12 months after laying of the GCA, the habitation of the short-necked clam was confirmed. It was confirmed that the overlaying sand of the GCA might build the environment where the habitation of the short-necked clam was possible.

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 A small tide pools on nature tidal flat around estuary were evaluated of important for fish habitat condition. However, there are few studies about effects of fish habitat of constructed tide pools on the artificial tidal flat in a canal area. The seasonal occurrence pattern of fishes and benthos and water quality at small tide pools in Keihin canal of Tokyo metropolis were examined and compared some small tide pools and shallows.The results suggested that artificial tide pools have important ecological function for fishes including rare species. And it is necessary to design the tide pool of a variety for fishes.

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 A sediment transport calculation considering cohesive force is proposed to deal with transport phenomena of cohesive sediment. In the proposed calculation, each sand particle is assumed to be surrounded by a thin layer of clay, and a critical Shields parameter and a bed-load sediment transport rate are modified to include cohesive force acting on the sand particle. The proposed calculation is incorporated into a coupled fluid-structure-sediment interaction model, and applied to wave-induced topographic change of an artificial shallow. Numerical results show that an increase in the content rate of the clay, the cohesive force per unit surface area and the water content causes an increase in the critical Shields parameter and a decrease in the bed-load sediment transport rate, and accordingly reduces the topographic change of the shallow without any change in its trend. This suggests that mixing clay in the pore of the sand particles can reduce the topographic change of shallows.

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 In order to utilize the products made of converter steel-making slag in marine area, knowing the leaching behavior of alkali substances and the pH rising of seawater is necessary. Most of the reported experiments for this purpose have been performed in closed system using such as a cylindrical container, but pH change under water flow in opened system is important. In this study, the experiments using large scale flume (L=6.5 m, W=0.5 m, H=1.2 m) with artificial seawater flow were performed. Five kinds of samples, 1) three kinds of steel-making slag of which particle size is 0 - 30 mm, 15 - 30 mm, 30 - 85 mm respectively, 2) artificial stone, which is solidified steel-making slag with hydration reaction, and 3) reformed soil, which is dredged soil mixed with converter steel-making slag, were used. pH values of the seawater sampled from 40 parts of the flume simultaneously were determined, and pH distribution maps were drawn with time. pH rising of the seawater for steel-making slag were 0.16 - 0.35, and slag with different particle diameter showed different behavior. On the other hand, pH rising of the seawater for artificial stone and reformed soil were within 0.04.

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 Examined the possibility by performing a model experiment of submerged mound without soil stabilization from mixture of dredged soil and converter slag which adjusts to the soft ground as substitution materials of building stones.
 Measure shapes model of submerged mound sink into the soft ground and destruction situations after the solidification of mixture of dredged soil and converter slag tried the evaluation of the result by numerical computation.

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 Artificial tidal flat has been constructed by use of steel slag as filling materials. Three layers composed by 30-80mm steel slag, 0-25mm steel slag and coverage sand are proposed to realize stable structure without leaking of constitutive materials into lower and coarser layers.
 FEM analysis of consolidation settlement by use of elasto-plastic constitutive soil models has been introduced into the construction management of artificial tidal flat. Based on predicted consolidation settlement of ground for 30 years after completion of construction, optimal heights of filling material and sand coverage are determined at the construction stages.

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 Uplifting the ground by pressure injection of slurry soil is effective as a restoration method of tidal flat subject to consolidation settlement. This method ensures compatibility between maintenance dredging in ports and maintenance of tidal flats. In this study, we have made a field experiment to examine the applicability of the proposed method and confirmed the auxiliary methods to uplift the ground smoothly. By use of the distribution of S-wave velocity obtained by a surface-wave exploration, the shape of slurry soil injected in the ground has been estimated. It is confirmed that the estimated result agrees well with the volume of injected soil. In addition, the uplifting shape of ground surface in the field experiment has been reproduced by FEM analysis.

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 In the construction site of tidal flat made of dredged clayey soil, submerged breakwater and seawall are developed at first and coverd sand layer. If the foundation is firmly, submerged breakwater and seawall are able to construct with direct set of gravel. Foundation is soft condition on the contrary, ground improvements are need. In this study, applicability of geotextile bag filled with dredged clayey soil is examined to construct submerged breakwater on soft ground instead of gravel. Centrifuge model tests and numerical analyses were carried out to construct 3m of height of submerged breakwater using geotextile bag on normally consolidated ground.

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 In order to establish a restoration technique for eelgrass bed of Zostera marina in coastal region where thick sludge deposit is present, the applicability of granulated coal fly ash as the construction material of the growth base was investigated. Although the granular artificial growth base showed the tendency of being affected by wave actions at low tide, it had eventually stabilize sufficiently. Porous structure of the growth base contributed to the rapid growth of the rhizomes and roots. As a result, it was possible to maintain the eelgrass bed in the region and, in turn, to enhance the stability of the favorable coastal environment. It was concluded that the eelgrass growth base of granulated coal fly ash is an effective technique to establish a stable seagrass bed in coastal waters.

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 Coral reef and seagrass vegetation are attempt to coastal and island area of southern part of the Arabian Gulf. In this water a large number of fish and marine mammals such as dugongs and green turtles are inhabited to form very rich marine ecosystem. As an extreme example global increase of sea water temperature should be noticed. In the Arabian Gulf after 1996, high water temperature above 36 deg. C. was occasionally observed, when a large amount of damage on coral were reported. It is necessary to preserve ecosystem and biodiversity by coping with natural environment changes. From this standpoint, authors develop new methods with practical applications for coral and seagrass which enable to adapt to future abnormal seawater temperature increase.

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 Sea weed beds have important functions as water purification, spawning and nursery grounds for valuable marine resources. In recent several decades, sea weed beds have been decreased remarkably by coastal reclamation, pollutant discharge from land area and gathering up of the sand from sea bed in the Seto Inland Sea, Japan. Therefore, the Japanese fisheries research institutes that located coastal areas have been conducted planting experiments of sea weed beds in various coastal areas for about 30 years. However, there are few successful outcomes despite their efforts. In terms of environmental condition, various factors must be considered for developing sea weed bed using the artificial reefs and sea weed enhancement structure. Recently, it is neccesally to consider the stability of structure against sliding resistance, toppling and lifting force on the seabottom. Therefore we developed an artificial reef as the seaweed enhancement structure with the functions of the current control and the high stability on the sea bottom.
 In this study, we tried realizing the former function by the hydraulic experiment and sliding resistance tests using a real scale model similar to the actual scale spikes. From the results of tests, we developed a theory for calculating the coefficient of static friction of various shapes spikes installed at the bottom of the reef made of concrete. Besides, we proposed a method for calculating the coefficient of static friction of the spike even if the bottom sediment conditions, facility conditions are different. Also, we examined the effect of fouling function of algae around the structure, which was settled at the real sea bottom by measuring the concentration of algae and aggregation of fish juveniles.

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 Comprehensive measures for protecting marine biodiversity have recently been initiated in Japan. In 2011, Japan's Ministry of the Environment adopted a "Marine Biodiversity Conservation Strategy," and has started a process for designating marine protected area (MPA). Sites that are important for natural resource management need to be selected in MPA designation. To identify such sites, decision-makers must refer to accumulated fishery data and the experience-based knowledge of local people, as well as scientific knowledge, specifically oceanography and ecology. Currently, in Tsushima City, Nagasaki prefecture, local fishermen are playing a central role in considering an MPA aimed at sustainable fishery resource use. Thus, our research involved a zoning exercise based on collection of data on the fishing environment surrounding Tsushima Island, as well as on Geographic Information System (GIS) data. On-site observations of the sea off Tsushima Is.'s north coast were conducted to examine the relatedness of techniques for ocean structure and habitat zoning, and a summary is provided.

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 Barren ground is widely distributed in the sea area. The coastal structures to make the algae place have been constructed for about ten years. However, it is feared that the decrease in the effect of seaweed creation by the aged deterioration of the substrate and water temperature elevation in recent years. Field investigation concerning distribution of seaweed beds and physical environment were performed in fishing port of Hokkaido. In this study, the results of the field investigation are introduced. It is found that one of the causes is feeding pressure to seaweed by sea urchin. It is strongly dependent on water temperature in winter. To control the feeding pressure in the situation of the elevated water temperature, it is necessary to improve flow velocity by raising the rear steps.

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 For an island (called Mubarraz Shoal) located in the southern part of the Arabian/Persian Gulf, we performed numerical simulation, considering tidal and drift currents to study about the current and flow routes of coral eggs and larva around the island. On the basis of results, it was identified that eggs and larva were transported to the southeastward as northwest wind was significant all the time around the island in the sea area. However, the transportation interval is varied according to the strength of the wind. Accordingly, it was estimated that coral eggs and larva may stay near the island at the time of the transportation in case of light wind. Moreover, consequently, we made a comparison between 2D and 3D simulation results about the transportation interval. We found that the difference has increased when the wind is strong. Farther, the effect on one directional wind was examined by 2DV. Throughout, it was identified that there is a necessity for increasing number of vertical layers. It is because, when wind is stronger, the difference of current speed between the surface of 3D and 2D simulation has increased.

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 In this paper, by analysis of generation structure of population of created from observation results of larvae of the clam Ruditapes Philippinarum in Tokyo Bay, average growth rate and the spawning date of larvae was estimated in a rational manner. We could create a simplified growth model taking into account the individual differences of the larvae of clam Ruditapes Philippinarum in Tokyo Bay, and prove the validity of the growth model reproducing the results of the observations shown in distribution of frequency of appearance of larvae of different shell lengths. Also, we created a vertical movement model taking into account the individual differences with the difference of density between the sea water and the larvae serving as the impetus and proved the validity of this model by conducting a basic vertical reproduction simulation.

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 We conducted field observations and experiments on a natural tidal flat to elucidate the ecological function of the mud snail; Batillaria cumingii and species interactions among B. cumingii, the hermit crab; Pagurus minutus, and benthic diatoms. In the natural tidal flat, 77.5% of P. minutus used the empty shells of B. cumingii. Although separately enclosed B. cumingii and P. minutus decreased the density of diatoms, this effect was reduced by mixed treatment. B. cumingii, as an ecosystem engineer, supplied a habitat for P. mintus and facilitated nutrient cycling but these functions were lost in an artificial tidal flat. We need to consider such an ecologically important species on a preferential basis while creating valuable tidal flats.

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 For the enhancement of ecosystem services in coastal area, it is worth to consider a comprehensive evaluation of targeted environment by a well-known indicator species. Thus, we have selected a marginal migratory goby (Acanthogobius flavimanus) as a comprehensive evaluate species.
 As a result, a hatching season of gobies was determined as longer than the said period, and needed to consider the difference of growth speed for each year. Hatching group fraction obtained from total length composition diagram, was an effective analysis technique. It was potentially able to capture the lifecycle of gobies for each location. And the spatial distribution of a specific hatching group was potentially able to determine the routes of migration.

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 For the purpose of acquiring the biological parameter in cold region sea, this study presumed the Light-photosynthesis curve of phytoplankton and acquired the the maximum photosynthetic rate and the optimum light intensity for 11 cases in 8 sea areas surrounding Hokkaido. The maximum photosynthetic rate is the range of the value of the literature values in the low nutrient, low temperature, and high temperature sea areas, so the value of cold region sea does not change a lot as compared with the literature value. The optimal light intensity was near value of the literature value of Honshu or Hokkaido. Furthermore, as a result of calculating the amount of primary production by ecosystem model, it was 29.04~63.21 and 32.54~185.87 mgC/(m²·day) at Musashi Bank and the 4 areas of the North Japan Sea, respectively, and the feature of the North Japan Sea was shown. When primary production of cold region sea will be considered in the future, it is thought that the result of this research serves as effective knowledges.

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 An inexpensive GPS fish finder which is built with side scan sonar function is applied to measure nearshore zone topography. To estimate a survey error by the GPS fish finder, a survey using Total Station had been con-ducted to achieve qualified accurate topography data set. The survey data using Total Station and GPS fish finder are compared. Then, it is found that an survey data accuracy using GPS fish finder is as much as 1.2 to 1.6 times of the error that is accepted by the legal criteria (survey law and hydrographic law), therefore this survey techniques using GPS fish finder cannot apply to a legal survey, but can apply to an environmental study that require reasonably accurate topography. In addition, to develop an aquatic GIS including topography, water quality and bottom condition data, an effective measurement procedure of water quality is also described.

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 We developed a new drifting buoy using Android smart phone. The drifting bouy can detect its position using GPS system and also measure wind velocity and direction. The measured data can be immediately transmitted to a distant location by 3rd generation mobile phone network. Field tests were conducted to verify its basic function and found that the system can work in nearshore area and may be applicable to monitoring spilled oil drift and its forcast.

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 A GPS buoy can measure deep water waves at a point of 100-400m in water depth and 10-20km off the shore line. Although the principal wave directions are determined in routine works, the directional spectra are not estimated yet since the method for estimating directional spectra has not been developed. One of the difficulties lies in that the equipment moves intricately owing to wave and wind actions. Under this background, the motions of the GPS buoy were simulated by a numerical model with the assumption that the buoy moves toward the same directions of the water particle with the same amplitudes in directional sea conditions. The directional spectrum analyses were carried out by EMEP. The estimated directional spectra show good agreement with the ones simulated with a numerical model. In this study, the effect of variable winds is found to be negligible in directional spectrum estimation.

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 Coastal zone mapping technics using commercial handy GPSs is developed and applied to survey an area that is too small to apply an airborne laser survey system or aerial photograph survey and too large to apply a Total Station survey. A quasi DGPS correction method is applied to reduce a survey error and three dimensional affine transformation is applied to original GPS data set (horizontal x, y and vertical z data). As a result, reasonably accurate topography data set which is equivalent to mapping information level 2500 (reference scale 1/2,500), can be achieved. Then, transformed data set is processed by GIS software to draw a topography map. This data process operation is now web-based and can be applied by anybody.

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 Acoustic exploration, core sampling, and other related investigations were performed to identify seabed surface including sedimentary structure of suspended sludge layer in Tokyo port. We examined the viability of the appropriate frequency settings according to the research object by clarifying the relevance between the result of acoustic explorations with different frequencies and the soil properties.

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 A three-dimensional coupled fluid-structure-sediment interaction model is applied to the development of wind waves to examine the computational capability of the model. Furthermore, wind-induced drift behavior of a shipping container floating on the water surface is investigated using the model in terms of force acting on the container. In the development of the wind waves, numerical results are reasonably consistent with experimental data in terms of an increase in the significant wave height with the fetch. In the wind-induced drift of the container, numerical results show that the inertia force is dominant in the force acting on the container compared with the drag force, and suggest that it is essential to consider the inertia force when predicting the wind-induced drift behavior of the container.

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 Yatsushiro Sea is a closed water area, and the wave height is low. Therefore, the sea water exchange with open area is not good. Furthermore, the driftage is running from Kumagawa River, and they drift with the tidal current and wind effect. In this study, drift characteristics of the driftage in Yatsushiro Sea are investigated by a drifting small buoy system equipped a GPS receiver, numerical analysis, a field work, inspection and a questionnaire survey. As a result, it was confirmed that the direction of the wind have a great influence on the drift characteristics of the driftage.

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 Water jet barrier was studied by experiments and numerical simulation in order to contain or collect spilled oil on the sea surface. High-pressure water jet obliquely injected to the water surface forms an exlusive zone enclosed with a parabolic front line. Floating oil can not come inside the exclusive zone.
 Experimental measurements were carried out on characteristic lengths determing the size of the exclusize zone. The measured data were arranged to eqations providing the lengths.
 Numerical simulation was also conducted using a particle model and compared to the experiments. Good agreemet was found between the experiments and the simulation.

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 It was reported that the drifting Japanese commercial fishery vessel which was about 30 m long was found in the Canadian offshore region. The vessel was flown out by tsunami of the Great East Japan Earthquake at the Hachinohe port in Tohoku district in Japan. Based on hints of the drifting vessel found in the Canadian offshore region, the influence of leeway coefficients on the tracking simulation of drifting objects in the North Pacific is examined using leeway coefficients from CGADD, wind and current model climatology. The simulation shows that the drifting vessels in the Hachinohe offshore region have arrived in the American and Canadian offshore region for about 1 year like the actual event. Smaller leeway coefficient tend to decrease more signicantly the clockwisze trajectory size from the North American offshore region to the Hawaii islands offshore region. Moreover, drifting objects tend to stay in the region between the Hawaii islands and the North America which is Great Pacific garbage patch. The total arrival number of drifting objects and the frequency of shorter passgage time also tend to decrease.

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 One of 10 scenarios to be considered for planning and designing an arctic structure is an interaction between a multi year ice floe and a structure during summer. In this interaction the ice floe has limited energy. During winter and break-up season, ice floes seem to have infinite energy, then the limited stress scenario is applied. In this limited energy scenario, the ice floe has linear kinetic energy before the interaction. After the interaction, that energy will be conserved as the sum of kinetic energy of the floe and crushing energy which would consumed during ice crushing. The crushing energy is the difference of kinetic energies between before and after the interaction. The crushing energy can also be obtained by integrating the ice load — penetration distance relationship. By equating those two crushing energies, the penetration distance can be obtained. The ice load can be calculated from the ice load — penetration distance relationship. However, this formulation strongly suggests that this scenario is not needed unless the encounter rate is extremely high during summer and extremely low during winter and break-up season.

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 The scaling effect of ice load acting on offshore structure is shown through the relation between ice pressure and indentation area, and there have been several explanations on the effect. Although there is clear explanation which applied the fractal theory of Palmer and Sanderson (1991) to one of them, there is little data of fractal dimension D. Systematic tests on fractal dimension D are required by the use of sea ice fragments produced by crushing failure.
 In the research, indoor tests on D are conducted to examine fractal characteristics. There exists fractal properties on sea ice fragments produced by crushing failure, and very little dependence of ice temperature on D. The effect of density and crystal structure on D is little. Tests data on D ranges from 2.16 to 2.39.

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