In the previous study, we have developed a water chamber type breakwater with a dissipative front wall comprised of inclined plate array and a horizontal plate at the bottom. It was intended as an improved water chamber type breakwater comprised of impermeable walls. Especially for the use in the sea area where the tidal difference is comparatively large, say larger than 3m difference. In this study, supposing that the clearance height between the bottom plate of a water chamber and a sea floor is comparatively large because of supporting piles in deep sea, influence of the clearance height on the performance of the breakwater has been examined extensively. For instance, wave transmissions and reflections, and also mean currents about the breakwater. It has become known that the clearance height is not so critical for the breakwater performance.

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In the Inland Sea of Japan, influence of nutrient loading from rivers and out of the sea on chlorophyll a concentration was estimated. The sea was divided by 24 boxes in the calculation. Sensitivity of each river and outside of the sea, west-side and east-side, to chlorophyll a concentration in each box was analyzed. The results of the sensitivity analysis showed the followings. The nutrient loading from the east-side was the most effective for the boxes from the Sea of Aki to the Sea of Harima. The effect of the nutrient loading from the west side was difference between August and October. In addition, although the Takase River, the Asahi River, the Yoshii River and the Ashida River affected the whole the sea, the Ota River, the Oze River affected only the boxes from the Sea of Iyo to the Sea of Hiuchi.

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Seto Inland Sea is the largest enclosed coastal sea in Japan. This sea is greatly influenced by incoming rivers and nutrient concentration sometimes makes the area susceptible to unusual events, such as red tide. In this paper, to clarify the contributing factors for the variation of water quality in Seto Inland Sea, EOF (empirical eigenfunction) analysis was applied to the monitoring data of COD (Chemical Oxygen Demand), T-N (Total nitrogen) and T-P (Total Phosphorous), which obtained form 1982 to 2001. Main results are as follows: 1) The first principal component which is obtained by EOF analysis reflect the effect of load form incoming rivers. 2) The second principal component may have some connection to the variation in main channel area (Bisan Seto area). 3) The variation of water quality in Seto Inland Sea can be described by using top three principal components.

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Separately water quality into the before increase of red tide occurrence becomes remarkable (1987 April-1998 March) and the after increase of occurrence becomes remarkable (1998 April-2004 March), cluster analysis was done. The tendency to change of environmental characteristic before and after increase of red tide occurrence was examined at each sea area division by cluster analysis. Ariake Bay was divided into 6 zones as follows, head of bay north and west part and head of bay east part and Chikugo river estuary front, middle and entrance of bay. In order to correspond with this division, occurrence of red tide in sea area was rearranged, connection of increase of red tide occurrence and characteristic of variation of sea area environment was investigated. Middle and entrance of Ariake Bay, after 1998 when red tide occurrence increases, rise of water temperature, transparency, COD, PO4-P and decrease of (NO2-N+No3-N) /NH4-N ratio which are cause and factor of red tide increase, became clear.

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To ensure the sustainable development of coastal areas, the Integrated Coastal Area Management (ICAM) approach has been required. The development of efficient management plans of complex ecosystems subject to significant human pressure cannot occur with the absence of science. For the development of the ICAM of Genka sea where is well known as the habitat area of Ryukyu sweet fish, a comprehensive observation of sea currents and water quality has been conducted. From the results of the observation in the summer season, characteristic currents of internal tide and water quality distributions are discussed.

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Southern part of Keihin Canal in Tokyo bay is highly urbanized. The water is warmer than the other part of Tokyo bay because of thermal pollution from many industries. The lack of DO is also severe. Some countermeasures improving the water quality, e. g. small artificial tidal flat, have been considered. However, because of the lack of information of water quality, the efficiency of these countermeasures is not clear. In order to clarify the environment in Keihin Canal, water quality is measured every 2 weeks at fixed points in and outside of the Canal.
Following results are obtained. 1) In autumn, anoxic water of the canal possibly flows out into Tokyo Bay estimated by the T-S data. 2) The surface water temperature is 2°C higher than the outside of the canal.

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Water bloom and nutrient loading in Hasunuma seaside park pond which is consisted of brackish water and located in Hasunuma Watetr Garden in Kujyukurihama coastal line in Chiba Prefecture was investigated. In this pond, the massive water bloom (Aoko) has been observed in summer in recent years, but there are no rivers into this pond. As results of this study, the followings were made clear. (1) The main nutrient loading source was considered as pollen of Pinus thunbergii as sandbreak wood, excrement of Anas platyrhynchos as immigration bird and rainfall including NO₃-N, (2) The dominant species of water bloom were Anabaena spiroides and Microcystis aeruginosa in summer and Cryptomonas spp. in winter. (3) The peculiar loading source of nutrient against seaside park pond should be paid attention to preservation the water environment in seaside area.

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We investigated the geography by the echo sounder and the sediment surface with the side scanning sonar, and collected the sediment cores at three points off Kumamoto City, to environmental reconstruction of the history of oceanic conditions since the 1950's, and to evaluation of the influence of sediments on marine organism.
The sandy bank off Yokoshima has been lost the function as the habitat of marine organism, because new sediments are not deposit on the slop and bottom in the dredged holes, and the mats ofModiolus comptusare not distributes on the surface of the bank. Muddy sediments in the Kumamoto area deposited after the latter half of 1970's are thick (ca. 80cm) off Midorikawa River, and became thin toward the north (less than 1cm off Kikuchigawa River). The limit of diffusion in mud exists off Yokoshima. The rapid increase of the haul ofRuditapes philippinarumwas closely related with the expansion of the sediments mixed coarse grains such as the shell fragments, sand, and gravel. In addition, the individuals of the clams increased in the sediments with less than 60% of mud in core sample.

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It is difficult to clarify the environmental condition in tidal flat because of the complicated interaction of atmosphere, sea water, land and creature. The thermal environment is an important factor in water quality closed relationship phytoplankton growth and activated biological. The objective of this study is the characteristic grasp of thermal and the attempted to calculate the numerical thermal model simulation in the bottom mud at tidal flat. The thermal water or bottom was observed at three sites that were different in the ground level and the meteorological variables was observed using an weather station deployed in the inter-tidal zone near Kumamoto Port As a result, the thermal water and air temperature influenced not only just bottom surface but also the interior bottom at tidal flat and the use of seepage flow in the numerical thermal model improved the accuracy of the model.

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The organic sediment moves with water flowing in estuary. It is carried to the river with flood tide from river mouth, and settles on the riverbed at a tidal flat. The organic sediment settled there causes the environment deterioration and loss of waterside scene value. Then, the environmental quality improvement technology was proposed using fly ash for consolidated sediment.
We established the construction technology for environmental improvement at riverbed covered by organic sediment. The infiltration-pillar was constructed as a method of supplying oxygen into consolidated sediment by the water movement in the pipe with the ebb and flood tide. Formation of the water cycle by construction of infiltrationpillar was confirmed by seepage flow analysis. After infiltration-pillar was constructed, the effect of the environmental improvement decreased the ignition loss in the sediment, and it was confirmed to decrease the nitrogen in the pore water.

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Kagoshima Bay, which is located at the southernpart of Kyushu Island, is composed of innermost (Aira caldera) and central (Ata caldera) basins. Innermost basin is connected by only one narrow channel, called Nishi Sakurajima Channel since an eruption of Mt. Sakurajima in 1914, that connected Mt. Sakurajima with Ohsumi Peninsula and closed Sakurajima-seto channel. In addition, expansion of Kagoshima Port makes the channel narrower. As a result, current system, which controls water quality in the bay, might be changed. Direct measurement of current system is difficult in the bay, therefore bottom sediment sampling is applied to estimate the current system. The bottom samples for this study were collected perpendicularly from 24 stations at the area of Nishi Sakurajima Channel to Off Hayato Santo. This study reveals that the current system in innermost basin is composed of three major current systems.

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In this study, we investigated the influence of sediment nutrient release and sediment oxygen consumption for the redeposition of suspended sediments from the sand capped sediments. It examined by the experiment of nutrient release and the sediment oxygen consumption in Tokyo Port Wild Bird Park and Minatomirai area of Yokohama Bay. From the study in Tokyo Port Wild Bird Park and Yokohama Bay, we found following results.
There is the good relationship between the sediment quality, nutrient release and oxygen consumption rate. It became cleared that the durability of the sand capping effect, to improve the sediment, and equilateral correlation of sediment quality and sediment oxygen consumption.

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Blue tides, upwelling of anoxic water, are a major environmental problem in Tokyo Bay because they cause mortality of benthic animals in shallows and tidal flats. There are three types of sources of anoxic water containing hydrogen sulfide: dredged trenches, flat bottom at the head of the bay, and navigation channels. To consider remedies for this problem, it is important to clarify each contribution to occurrence of blue tide. It is, however, difficult because of the lack of time series data for the total amount of hydrogen sulfide in each of water. Thus, in the present study, focusing on dredged trenches as a first step, we developed a simple and reliable methodology for the estimation of the total amount of hydrogen sulfide. We utilized the data of pH and ORP collected using a water quality sensor, which have a good correlation with the concentration of hydrogen sulfide. Moreover, we found that the accuracy of estimation is quite improved if we use information of hydrogen sulfide concentration at the bottom. The proposed method is rather simple and very effective because those data are usually available in conventional monitoring.

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This study was carried out to investigate the evaluation method for shallow waters, as suitable area for the short necked clam breeding fields and the eelgrass beds in the area of Seto Inland Sea of Yamaguchi Prefecture. To evaluate the sites comprehensively, we utilize GIS on the analysis of the environmental and social conditions, combined HEP on habitat suitability. We observed the distributions of short necked clam and eelgrass in recent years along with important environmental factors for them. Comparison of our findings with the data obtained from the model analysis indicates that our evaluation method can be applied for the site selection in this area. Consequently, it is considered to be effective GIS with HEP for evaluating habitat suitability for the shallow-water sites.

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It is important to know temporal and spatial change of environment to evaluate its status. Especially, vertical profile and temporal change of water quality are taking an important role on Tokyo Bay environment, since strong stratification and hypoxia in the bottom layer during summer are easily changed by wind driven mixing. However, it is not feasible to obtain a dense data for both vertical and temporal domains for wide area of the bay because of the cost. This research aimed to establish a cost-effective method for the monitoring of vertical profile of the hypoxia by a simple set of a thermistor chain and a dissolved oxygen (DO) sensor. The key factor of success of the method was based on similarity on vertical profile of temperature and DO.

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Recently, there are many researches on sea level rise due to global warming. It is considered that problems on aquatic environment and disaster prevention will be caused by the sea level rise. Variations of high water level (H.W.L.) and low water level (L.W.L.) rather than that of mean sea level (M.S.L.) are important to discuss countermeasures against these problems. However, few researches on the long term variations of H.W.L. and L.W.L. have been carried out, and the characteristics of them are not made clear. In this study, in order to evaluate the variations of H.W.L., L.W.L. and M.S.L. the tide in Ariake Bay is discussed by analyzing tide data, numerical test and theoretical analysis. As a result, it is clarified that H.W.L., L.W.L. and M.S.L. have risen after 1960's, and the rate of rise increased in order of L.W.L., M.S.L., and H.W.L.. In addition, it is implied that M.S.L. rose corresponding to the decrease of tidal current due to the reclamation in Isahaya Bay.

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Monitoring on the shore line restored with three types of soil, dredged material, sand and mixture of them, was conducted to investigate the stability of its internal ground structure. Mini-CPT was introduced to determine internal soil properties by measuring both penetration resistance, qT and the difference of generated excess pore pressure, Δu.
As the result, it is confirmed that the inner parts are stable after construction despite the erosion of the surface due to high waves. It is also conformed that Mini-CPT is effective to investigate the internal ground structure on the intertidal zone where saturation and unsaturated are repeated

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It is possible that an underwater noise and vibration which occurred by marine construction have an influence on marine benthic invertebrates and fishes. For the present, we must to consider that the environmental impact about an underwater noise and vibration. There are many reports about the influence of underwater noise about fishes. However, the influence of an underwater vibration on the benthos is not clear. Therefore, we experimented to prove that the influence on the benthos (Bivalve, Gastropod, Crustacean, Fish) by the vibration.
As a result, the vibration was caused liquefaction and burrowing benthos pushed out the surface. The influence appeared remarkably by 110dB or more and 30Hz.

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Ariake Sea is typical the large-scale closed bay and contains the regional scale tidal flat that account for 40% of Japanese tidal flat total area. A lot of characteristic creatures inhabit Ariake tidal flat and influenced remarkable the environmental functions, topography, grain size water contain, organic substance and sulfide etc. However, the species and the populations of the creature have been decreased in this recent environmental degradation. The aim of this study is to evaluate the habitat environment and recommend the environmental improvement at tidal flat in Ariake Sea. At first we conducted the resource research and the field observation to grasp or in order to grasp and analyze the current tidal flat condition. As a result, the data obtained via cluster analysis was classified into 6 groups and explored the relationship between the environmental characteristic and the habitat.

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It is feared that Ariake Bay has recently fallen into a vicious cycle of rapid environmental degradation that includes changes in biota and decreases in its number and species, as well as water quality and sediment deterioration. In particular, sediment deterioration is one of the major factors causing hypoxia and other signs of environmental degradation. As a part of restoration technologies, we performed to restore the sediment with setting up some kinds of “artificial nest hole”, which employs water level difference and tidal current and transports upper layer water into the sediment in the sea and tidal flat area. As a result, the sediment made better slightly, on the other hand, the habitat expected as environmental remediation of sediment had improved markedly.

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Ariake Bay, a typical closed bay on the west of the Kyushu Island, is a sea area where a vast tidal flat develops. Recently, various environmental degradations are reported occur in Ariake Bay, as red tidal and anoxic water. In this study, the ecosystem formation process by recovery of shoreline, the aim in this method is to establish the technology that can artificially restore the tidal flat and the shoreline in front of embankment development and to recover and maintain the ecosystem, was investigated in Ariake Bay. We investigated the characteristics of spatial distribution of habitat from relation to topography, sediment and distribution situation of benthos. As the result, the peculiar environment such as water-route influences distribution situation of benthos.

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The natural coastline has been almost replaced by the concrete construct on such as coastal embankment for the land reclamation and disaster prevention in Ariake Sea. The natural habitat for benthos and salt plant had been getting loss; and then the environmental deterioration becoming advanced in Ariake Sea. Agricultural Administration Office promoted the harmony with disaster prevention and environment using embankment and jetty in Tamana Yokoshima coast. In this study, firstly searched the volume of sediment movement at the jetty area by the river and tidal flow and confirm the stability performance in sediment, which the benthos could be alive. And then, modeling the Habitat Suitable Index by using the topography, bottom quality and benthos calculate the habitat environment in the feature.

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The Sone tidal flat in Kitakyushu city has a dry flat of about 517ha during ebb tides. It is one of the nicest spots for the wild bird observation through the four seasons. It is also famous as the breeding ground of Horseshoe crab (Tachypleus tridentatus). Although large-scale landfills have been recently constructed around the Sone tidal flat, number of Horseshoe crab breeding pairs laying eggs have been increasing. However, they suddenly decreased for the past 2 years. The aim of this study is to understand physical habitat environments of Horseshoe crab larvae and bottom sediment characteristic through field studies.
This study confirmed the bottom sediment characteristics, especially about the bottom sediment hardness. In addition, the relationship between the bottom sediment characteristics and the number of the Horseshoe crab larvae observed was discussed.

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Yatsu Higata is one of the most significant remaining tidal flats in Japan. It is located on the inner part of Tokyo Bay, and was registered under the Ramsar Convention in 1993. Therefore, many waterfowls come flying to Yatsu Higata and they feed benthos and seaweed. However, waterfowl drop nutrient-rich water in the tidal flat, and it acts as nutrient load to the tidal lat. In Yatsu Higata, nutrient load study and water quality analysis have been carried out so far. However, there have not been conducted any analysis about factors of water pollution at Tokyo Bay, such as nutrient load from water pipe placed at seawalls, water gate, and load of drops from waterfowl.
This paper explores the nutrient load from waterfowl and wastewater in Yatsu Higata through field studies.

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Construction of the Hyakken River, a diversion channel for the Asahi River, was carried out at the initial stage of the Edo period. Main structures such as weirs and gates were made of stone and skillful masonry technique was used. The construction works were carried under the direction of Eichu Tsuda who was the county reign of the Okayama province and he proposed many new ideas. The flood prevention system by the diversion channel and river mouth gate has fulfilled its function more than three hundred years. The advanced civil engineering technology used in the construction works is introduced in this study. It is necessary that we once reexamine the disaster prevention technology which the predecessor left for us now.

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In order to establish the technology for restoration of seabed sand at the area of sea around Bisa-Seto, this study analyzed the existing environmental condition there, proposed the direction of technology development based on above analysis, and implemented the proving experimentation to confirm the appropriateness of proposed technology.
In this study, the problems at Bisan-Seto were made clear by using the“Impact Response Flow Analysis”, and taking the lifestyle of fish and shellfish into account the comprehensive method to simultaneously restore the shallow area along coast line and offshore seabed sand was adopted.
Since there have been few studies on the restoration technology of seabed sand, the proving experimentation to establish this technology has been commenced and monitoring works been carried out.

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In latter half of 1900's, Eelgrass (Zostera marinaL.) beds were ever distributed over the approximately 590 ha of near-shore waters in Hinase-cho Bizen-city Okayama. However, one of the results of increased pressure such as recent landfill and water pollution has been the destruction of most of the coastal eelgrass habitat. Therefore, eelgrass bed restoration has been ongoing since latter half of 1980's, and Marino forum 21 Public Corporation and the agencies of the Okayama Prefectural Government have developed restoration technology for eelgrass beds from 1998. The project, which involved restoring eelgrass beds and creating habitats for each life stages of fishery products, had been planned by using technologies based on these results and the field studies in this development. First, in this study, based on the research in these sites, restoration policy considered with growth distribution of the natural eelgrass beds was set up. Second, some limit factors in eelgrass beds were detected quantitatively and this information was used to plan a design, a project execution and adaptive management.

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A project which contributes to the enhancement of ecosystem restoration, utilization, and disaster prevention function in the urban shore by constructing a wetland was planned. Since the area was restricted spatially, a terrace type sand flats bounded by rocky shore with bulkhead was employed instead of a sloped beach type wetland. It enabled to use adjacent water surface as living port facilities. Furthermore, the terrace type structure was enhancing disaster prevention function of the seawall by a counter-weight effect. For the detail designing, dimension and material of the wetland was determined scientifically sound way based on enrichment of biodiversity. It was also paid attention on implementation of an adaptive management for public participation and utilization. After the completion, the wetland have been in a utilization and monitoring phase for checking detailed topography, sediment quality, and underground water etc. for implementation of the adaptive management.

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A tidal flat, sand beach and shoal which were built in the inner part of the Keihin canal. In this area, environmental monitoring is continued from 2002. Benthos and sediments were investigated several times for a year. Flow velocity observation including continuously measurements were carried out in summer in 2006.
Although the sight where was constructed is low-salinity, low-oxygen, and high nutrition, a benthic community is formed here. This community is mainly consists of Polychaetas and Bivalves. Biomass of this community is unstable and is changed seasonally. And dominant species change every year.
In this sight, benthic communities are often reset by the attack of low salinity and low DO water-mass. From the continuation observation result of current, salinity, and DO, it was presumed that bottom water of a surrounding canal advances into a shoal.

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A big push began to promote environmental restoration in Japanese coastal zones. Tokyo bay is one of dense populated bay in eastern part of Japan. To facilitate an economical utilization and an environmental conservation in balance, a habitats creation project in urban canal area has been implemented. The facility had two 4m×8m pools with 0.5m depth sandy bottom on the rocky terrace of sea wall. These pools had a potential for a habitat of juvenile fish (gobies) and benthos. Partnership type collaboration was employed to make citizens active participation in the project supported by scientist and local governments. Special designed monitoring methods entertained participants of the project, and proofed high potential of the facility as good habitat for fish and benthos.

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In the Sea of Japan of southern Hokkaido, the area affected by isoyake (seaweeds withering phenomenon of a rocky shore) has been expanding. It is necessary to take the swift measures for restoring seaweed beds as soon as possible. It is thought that one of the causes of the continuous isoyake condition is the seaweed damage by northern sea urchin (Strongylocentrotus nudus).
The creation of seaweed beds was experimented by the artificial swinging material at Era fishing port in Matsumae-Cho. The artificial swinging material is made by the polyester cloth, it has Velcro ruggedness on the surface. As a result, seaweed beds of kelp (Laminaria religiosa) were formed. Moreover, it was found that its durability for oscillatory flow was about 4.4m/sec by the experiment of fluid drag force.

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Experimental study on marine environmental creation by using “wave-dissipating blocks surfaced with grooves” was conducted on the front side of breakwater in the Port of Hamada, Shimane Pref. These blocks were made thin and thick grooves on the surface, using modified steel mold. This procedure is appropriate for workability and cost performance rather than other methods such as using ordinary blocks with some attachment plates, etc. This study reveals that two types of grooves on the block show the different functions, i. e., thin grooves as substratum for algae such as kelps, and thick grooves as habitats for shellfishes such as abalones and turban shells.
As a result of several years survey, two types of grooves on the surface of the blocks are recognized as a certain kind of function for ecological environment.

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Seaweeds, sticking on various harbor facilities, are suspected to have small fishes and juveniles protect. Observed researches have been operated to estimate their function, but failed to get quantitatively detailed results. Accordingly, we have newly developed the collection technique with “hold net”. The numbers of fish species variety collected with the net were as 1.4-5.0 times many as those of observed. Similarly, the total numbers of individuals were 1.1-16.5 times. And sea cucumbers under 5cm were confirmed only by the collected. As those results, it is proved the collection of small fishes and juveniles in seaweed beds with the hold net could research in more quantitatively detailed than observed. It is convinced that those data are useful to assess harbor area.

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In this paper, we paid attention to Japanese spiny lobster Panulirus japonicus which lived in the fishing port facilities, and to contribute to habitation and multiplication had been strengthened. We selected Aoshima fishing port in Miyazaki Prefecture where P. japonicus was distributed and field survey was carried out about the living density, the habitat, spawning ground and catch yield from August, 2006 to December, 2007. As a result, pueruli and juveniles of the P. japonicus appeared in the hole of the size from the diameter 2cm to about 4cm that became empty the bedrock and a rolling stone. The growth stage from juveniles to adult of P. japonicus lived around the fishing port entrance and appeared the caisson, the armor block, and the wave dissipating concreate block. And incubated female appeared in the fishing port facilites, too.

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Field investigations and indoor experiments were performed to evaluate the environmental function of the oyster reef existing around the Nekozane River mouth in Sanbanze Shallows of Tokyo Bay in terms of the decomposition rate of organic matter. The number of living oysters and oystershells was counted to estimate their densities in the reef. Sediment samples were collected and analyzed to understand spatial variation in sediment properties around the reef. Indoor experiments were conducted to determine the oxygen consumption rates of oysters and oystershells in terms of water temperature. All of the information are integrated on GIS and the spatial variation in decomposition rate of organic matter inside and outside of the oyster reef. Very high organic matter decomposition rate of the oyster reef was obtained during summer, which is comparable to several times of that of sandy bed in Sanbanze Shallows. According to the historical aerial photos, the oyster reef remains for more than 10 years. These results show that the oyster reef has valuable and sustainable function of water purification.

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Because specific gravity would increase if the surface of a seed is coated with iron powder, the stability of waveinduced current increased. The improvement mechanism of stability was brought about by 13% of partial subsidence of the minor axis generated into the seed. The iron-coated seed subsided in the valley part of sand ripple generated in a bottom surface, and was buried with disappearance of the ripple. Therefore, the burial depth of the seed can be presumed from the wave height of sand ripple.
The germination rate increased the eelgrass seeds by iron-coating. Furthermore, the time which a bud emergence takes was shortened by about one month, and also increased the bud emergence rate by about 3 times. The reason is because a sprout of eelgrass seeds is promoted by an anaerobic condition. From this research, the appropriate coastal region for direct sowing of iron-coated eelgrass seeds, sowing period, and sowing density can be presumed.

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We confirmed that high coral community cover in top-shell snail (Tectus niloticus) aquaculture structure installed in the northern part of Miyako-jima Island, Okinawa prefecture. The purpose of this study is to grasp the reason why the structure has been functioning recruitment and growth of coral. As the results, it was suggested that the lattice structure in top-shell snail aquaculture structure functioned effectively recruitment of a coral larva. In addition, it was suggested that the measure-shaped structure functioned as to damp current speed at the time of the high surge and it has contributed to the growth of coral.

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The area of Tatsukushi bay in Ashizuri Uwakai National Park, is famous for its high coverage of coral community and existence of various ecosystems. However, large volume of mud and soil flowed into the bay by the flooding in 2001 and settled down on the sea bottom. The sediment that remains in the bay now gave serious influences on the coral community.
This research aimed at the development of the device to separate fine grains from sediment efficiently, and to remove fine grains on the sea bottom. We researched, manufactured and developed the practical device for the purpose through the site experiment and the basic examination lasting for several years, and used it in the nature restoration project in 2007 fiscal year.
As a result, it was verified that the sediment of about 20cm on the sea bottom was removed.
We believe that the development of this method and device could be applied to improve deteriorated tidal flat where sediment settled down etc. and other environmental restorations themes in the future.

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The large-scale coral transplantation has been implemented on the reef flat area at Kuta Beach in Bali Island of Indonesia. The transplantation area is about 1.3 ha and there is no other example like this big scale coral transplantation. The asexual reproduction was applied as transplantation method by fixing coral fragments using nail with cable-tie and the limestone was adopted as artificial substrate for coral transplantation. The major species of coral to be transplanted is Acropora sp. which was taken from the same coral reef area. More than a half year has already passed after the completion of the first coral transplantation and high degree of survival rate with more than 98% could be maintained until now.

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The Okinawa General Bureau of Cabinet Office has been performed various environmental investigations to realize coexistence of coral reef and port construction. It should be necessary to utilize the data provided by the investigation effectively. However, there was not a unified guideline by the past investigation. There was the case that an investigation item or precisions were different on each investigation. There was also the grasp of the general comparison and evaluation of the investigated data. Therefore we planed to make unified guideline of investigation methods of coral reef at the port of Okinawa. “The guideline of investigation methods of coral reef at the ports in Okinawa” was published in March 2007.

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The leading part of fishery infrastructure improvement project were local government, it benefits only coastal fishery. Recently, it is improving that technique of fishing ground creation. And request for creation of offshore fishery are increasing. In 2007, Frontier Fishing Ground Project was made formally, so creation of offshore fishing ground will be more propel. In this study, the purpose of obtaining fundamental data of mesopelagic zone, we operated field work in East China Sea. We compared result of current observation data and water quality data to past observation. Distribution of vertical nutrient salts and chlorophyll-a are consistence with past observation data. Exist of internal tide was conjectured during neap tide in St. 2..

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The GPS buoy can measure the coordinates of the vertical and horizontal position of the receiver equipped at the top of the buoy by the RTK-GPS method to an accuracy of centimeter every second. In the previous paper, we proposed a method for estimating the representative wave direction from the GPS information. In the method, first, the observed time series data were separated into components, then, the predominant direction is derived from the horizontal displacement having the maximum power, and finally the representative wave direction is determined with reference to the sign of the covariance value between the vertical displacement and horizontal velocity. Although this method can estimate wave direction in the full range of 360 degree, it has drawback in its computation time. In this paper, we therefore proposed a more efficient method in which the above numerical operations are carried out in frequency domain without applying inverse FFT. We applied this method to the observed data and discussed its adequacy and applicability.

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The Kyushu Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism has placed four High-Frequency Oceanic Radar (HF radar) at the Ariake Sea since 2005. The system named “The Ariake Sea current and ocean wave information system” provides the real-time information on surface currents and waves on the Internet.
This paper presents the results of the comprehensive investigations on (1) the accuracy of HF radar observation, (2) the expansion of the current observation area, and (3) the improvement of the ocean wave observation. These inclusive studies come to the conclusions that the accuracy of ocean radar was verified satisfactory, and the expected improvements of the system for measuring currents as well as waves were successfully achieved.

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The surface tidal current is influenced by sea-surface wind. So, we investigated the influence of sea-surface wind on tidal current data observed by HF Radar. At first, we carried out harmonic analysis in order to know sinusoidal tidal components. Then we studied the relationship between sea-surface wind and the 25 hours running mean values of tidal current by using multi-regression method. From the study, we obtained following results. (1) Tidal current obtained by HF Radar is strongly influenced by sea-surface wind. (2) The influence in shallow area is larger than the one in deep area. (3) The influence in summer is a little bit larger than the one in winter.

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In the ocean surface, there are currents generated by ocean winds. Wind driven-currents are nonstationary phenomena temporally and spatially. Wind driven-currents affect coastal currents. Therefore, the grasps of wind-driven currents are important. It is necessary to observe velocity of currents temporally and spatially due to estimate wind-driven currents. However, it is difficult to observe spatial velocity of currents and ocean winds by current meter and anemometer of stationary type. High frequency (HF) radar can be observed spatial velocity of currents. Although ocean winds cannot be measured directly by HF radar, it is possible to estimate using wave height, wave period, and the Sverdrup-Munk-Bretschneider's (SMB) method.
In this study, ocean winds were estimated by obtained wave height and period from HF radar and SMB method. In addition, wind-driven current was presumed using the estimated wind and bulk method. Finally, we developed self-contained estimation system of wind-driven system currents using high frequency radar.

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CADMAS-SURF is a useful numerical model to design maritime structure. Applicability of CADMAS-SURF for predictions of breaking waves or irregular waves has been studied. However, there are not many studies about the wave run-up problems. It is necessary to investigate the applicability of CADMAS-SURF for predictions of wave run-up.
This paper presents an investigation for applicability of CADMAS-SURF for predictions of wave run-up. In order to verify the accuracy of CADMAS-SURF, CADMAS-SURF was applied to several wave run-up conditions. The computational results are compared with the experimental results to show the validity and efficiency of CADMAS-SURF. In order to compare the numerical results using different mesh size, several numerical studies were carried out. The present study proposed the calculation conditions for numerical simulation.

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A method for making irregular waves in numerical simulation by a linear wave theory is simple and of great utility in a practical work. It is necessary to modify a horizontal velocity profile, because a total mass of calculated region increases with time by a mass transport. Although several studies have been made on modifying a horizontal velocity in the last few years, it leaves much room for improvement. We also have proposed a method for modifying a horizontal velocity that subtract Stokes drift. In the present study, an improved method for generating irregular waves is proposed. The purpose of this paper is to investigate the validity of the modified method. In the result, the modified method is applicable to a calculation of irregular waves.

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The CADMAS-SURF, which was developed by Coastal Development Institute of Technology (CDIT), has prominent feature in its versatility, and has been applied to many problems on coastal engineering. Since a long duration of wave incidence are required for random wave calculations, the computational time using the CADMAS-SURF increases drastically and it seems to be practical problem. The gradual increase of the mean water level is also reported. To overcome these problems, a new method, which combines the CADMAS-SURF and Boundary Element Method (BEM), is presented. The validity of the combined model is confirmed by comparing numerical results with theoretical ones for wave propagations of Stokes' 5^th order waves and random waves.

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CADMAS-SURF is one of the accurate numerical models that can apply to a performance-based design of maritime structure. However, there were a few application examples to irregular waves, because of the increase of computation time. Thus, a systematic study of irregular waves by CADMAS-SURF has been conducted with a cooperation of research group. The numerical simulations are conducted for transformation of irregular waves propagating a flat flume with a constant depth. The calculated spectra and representative waves are compared with those set as the target and the results of theoretical study. The characteristics of irregular waves generated by CADMAS-SURF are consistent with the existing knowledge. The modification of given spectra to make irregular waves is recommended to agree the spectra, significant wave height or significant wave period with the target at some point. The adequate selection of option parameter is required to avoid the numerical damping.

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The aim of this study is to investigate the characteristics of the height and depth of breaking waves for periodic waves, considering the effects of the groundwater table on them. A hydraulic model experiments and numerical simulation are performed to accomplish the aim. The experimental results of breaking index including the breaking wave height and breaking point on a gravel beach are compared with the existing experimental data on a sandy beach and the proposed breaking wave formula for computing breaker height and depth. Experimental results indicate that the higher the groundwater table, the deeper breaking point. Further, the breaking wave height is smaller than that in a sandy beach. The numerical model based on N-S equation solver is found to reproduce the wave fields affected by the groundwater table and its results are in close agreement with the laboratory data.

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