Eelgrass and seaweed beds are important places for ecosystem of coastal zone, and also fishing industry in Japan. Therefore, We have tried creating seaweed bed on the wave dissipating concrete blocks and the rubble mound of breakwater, at Togi fishing port in Isikawa prefecture. We were able to get four information about the design from monitoring the seaweed bed type breakwater. The first is the necessity of setting up the substratum of seaweed in accordance with maturity time of seaweed. The second is that of predicting the transportation range of its spores. The third is that of detailed investigation and development of measuring apparatus for the propagation of specific seaweed. The fourth is that of examining comprehensively the relation between seaweed bed succession and herbivorous benthos.
In Hamada fishing port of Shimane Prefecture, the improvement works are underway with a campaign of “Development of Fishing Port in Harmony with Nature” in line with “Marinovation Plan”. In construction of the huge submerged mound in front of the breakwater and the revetment, the construction method to add the function of seaweed bed has been applied, considering disappearance of a part of better coast due to the improvement works. After completion of a part of the submerged mound, the site investigation was carried out 12 times during 5 years to verify the effect of the works. On the basis of the monitoring survey results for seaweed communities, the effect of function of seaweed bed was verified and evaluated using the change of dominant species and the similarity index of seaweed commnities.
In the 2nd phase KANSAI international airport island, a gently rubble mound type seawall was adopted over more than 90% of the about 13km-long seawall, and also for the seawall, positive efforts toward seaweed bed formation are being made in order to create rich sea-area environment at early stage.As a result of supply of seaweed seedling that used seaweed blocks utilized in the 1st phase seaweed bed formation and net bag (spore bag) containing sporophylls, the area of the seaweed bed in the 2nd phase airport island where seaweeds are growing was about 18ha in October, 2002. We can say from this result that the artificial seaweed bed formation is contributing to the ecosystem in Osaka bay.
About the artificial algae zone added to the offshore structures, we examined the elementary method, the characteristic of algae zone and construction examples. Moreover, from examples of failure, the influence and the countermeasures of grazing pressure were shown. Next, the numerical model which predicts existing quantity of algae was developed, as the evaluation method of the structure which were added the artificial algae reclamation. The characteristic of this model is considering the environmental factor of offshore environment, and the grazing pressure. The first conclusion of this research is, the relation of algae existing quantity was able to be clarified with offshore environment, the ecology characteristic, and the grazing pressure. The second conclusion is, proper wave condition generates the current which controls the grazing pressure. The third conclusion is, water depth which can obtain proper light, generation of sufficient algae zone is expectable.
Waterfront area has been created by land reclamation and others, and has supported our social and economic activities. This paper first reviews the transition of the use of waterfront area under the change of economic, social, and industrial situation our country has been experienced. Then a summary of the recent policies concerning the use of waterfront area such as Special Zones for Structural Reform, Urban Renaissance, development of grove at waterfront, wide-area disaster prevention bases, and wind power generation are briefly presented. Furthermore, technical aspects to promote redevelopment of the waterfront area including reclaimed land are introduced. It is important to recognize the characteristics of coastal zone in redeveloping and revitalizing the waterfront area as well as reclaimed land, which would contribute to social and economic revitalization in the 21st century.
In 1997, the Russian tanker Nakhodka, weighing 13, 157 tons, sank off in the Japan Sea reportedly causing an oil spill of 6, 240 kiloliters. In spite of offshore oil collection attempts, and as a result of strong winds and rough winter weather, a large amount of spilled oil drifted into the Japan Sea. Consequently, vast amounts of this heavily emulsified oil washed up on the Japan Sea side shorelines. The oil spill had a serious impact both ecologically on the shoreline environment and economically on coastal activities such as fisheries and tourism. The purpose of this study is to assess the response process of oil spill from the technological point of view. The result shows that collaborative scientific and technological support for the response should be carried out under integrated coastal zone management policy as well as accurate oil response. It is also crucial to accumulate knowledge about integrated management of coastal zones based on day-to-day management in coastal regions. This report will clearly be a great contribution to the oil spill response strategy and coastal zone management policy in the future.
Hakusan is the oil recovery vessel for the open sea. This ship was planned to build because of the oil spill of oil tanker Nakhodka when it sank in January 1997. We decided to load the oil recovery system “the cyclone type”. However the cyclone type was difficult to collect the oil in the winter high wave and to collect the very sticky oil. Accordingly we developed the new type of the oil recovery system that was based on model-experiment. And the oil recovery vessel “Hakusan” which was loaded the most suitable oil recovery system completed in August 2002.
The oil spill accident of Nakhodka in 1997 made many persons (around 400 to 500 thousands) work hard to remove emulsified heavy oil to clean the coasts. They suffered from viscous oil because the conventional oil recovery equipment was not good for the oil of such viscosity of 500Pa·s. They had to use dippers and buckets by their own labor, because the access of heavy machinery to the coast from land or sea was difficult due to irregular terrain conditions and shallow water depth. This paper describes a labor saving oil recovery system for viscous heavy oil on the water surface in front of the beach. The system is able to skim oil from water/oil mixture which contains emulsified heavy oil. It is also able to transport separated oil for long distance without blockade. The performance of the system is equivalent to 150 persons while only 10 persons are necessary for operation. These results have been confirmed by pool test using emulsified heavy oil and operation test at sea.
A Iocal wind prediction model named LAWEPS (Local Wind Energy Prediction System) isdeveloped. LAWEPS is based on the computer fluid dynamics theory, and its goal is the accurate wind speed estimation with the accuracy of yearly mean wind speed error of 10%. Its validation results show that the wind estimation error is within 5%. LAWEPS is applied to the ocean surface wind estimation around Tokyo bay and Setana port area. Wind estimation is compared to observed wind data over the ocean. It is concluded that the wind estimation by LAWEPS has enough accuracy for practical use, and LAWEPS will be a powerful tool for wind estimation over the ocean.
In the field of coastal engineering, so far the wave hindcasting has been executed for several limited purposes such as the clarification of the cause of the disaster due to waves, the interpolation of missing wave observation data and the determination of design wave conditions for maritime structures since the wave hindcasting was usually expensive and special knowledge was sometimes required to the executions. Recently, the wave hindcasting models have been improved as seen in the successful development of the third generation wave models such as WAM, SWAN and Wave Watch III. In addition, accurate and reliable meteorological data for several decades has been supplied from the international organizations such as ECMWF and NCEP. Thus the simulation of ocean waves with those wave models and meteorological data for the past of tens of years becomes easier. The accurate and reliable wave information can be obtained for long term in various coastal areas where there is no wave observation data. In this paper, we introduce the recent situation concerning the wave hindcasting models and their applications.
This paper shows the development of wave theories and numerical methods for random wave transformations in nearshore sea. When estimating wave conditions acting on coastal structures, a suitable wave model should be chosen, depending on the situation. This paper also describes criteria for selecting wave models and shows several examples of wave predictions.
Estimation of wave height and period is in great importance for design of port facility. The harbortranquility is determined according to wave height distribution and occurrence probability in the target berth areas. The crown height of breakwater and sea wall is designed as those facilities protect the inner harbors and water-front areas from the acting waves. The wave transformation model with high accuracy is necessary to keep the harbor safe and effective. In the paper, the practical computation system for port wave is introduced. The energy balance equation model and Bussinesq equation model for wave is employed for estimation of wave transformation in shallow water and very shallow water area respectively. The data base including water depth contours and berth arrangements in the ports is attached with the computation system as the bathymetry data for simulation is completed in short duration.
In the past 25 years, many researchers studied nonlinear time domain simulation methods of free surface and floating body motions based on the potential theory. These simulation methods are called as numerical wave tank (NWT). To solve the simultaneous equations of ideal fluid motion and floating body motion, rational NWT solves both the velocity field and the acceleration field. This review paper presents theoretical and technological state of NWT. The basic mathematical formulation of NWT for floating body simulation is firstly given. Then, the application of NWTs for two dimensional and three dimensional problems are presented and the strengths and limitations of NWT is explained. The direction of future development 3D-NWT is also discussed.
Recent advanced computer technology encourages development of numerical simulation method of complex flow regime. Then, recent numerical simulation methods are able to simulate interactions between waves and coastal structures even for cases of rotational motions of viscid fluid. This kind of numerical simulation method has been applied to simulate mainly the interaction between waves and structure with vertical face represented by the breakwater. In the simulations, wave deformation, pressure on the face and wave overtopping have been analyzed, and acceptable reliabilities have been confirmed. Recently, the numerical simulation method has been developed to the three-dimensional problem for wave-structure interaction, where the vortex formed behind the structure is important. In this paper, applicability of the numerical simulation method in the estimation of the wave force on the structure is discussed. Moreover, the latest results of the application of the numerical simulation to the wave-structure interaction with asymmetric feature where the transverse force is significant are presented here.
A numerical analysis model, based on the coupling of a Boundary Element Method (BEM) which is applied to the region far from the structure where the fluid motion is less non-linear and a Volume Of Fluid (VOF) method which is applied to the region near the structure where the fluid motion is highly non-linear, is developed. Two methods were combined under the principles of continuities of the velocity and the pressure. The validity of the method was checked comparing the numerical results with the theoretical ones for wave profiles. Although the combined method showed the superiority over each single method, in the present state, several problems to be further settled were found on the numerical accuracy and stability.
Public involvement of four environmentally friendly construction project cases which authors directly or indirectly involved were described. The process regarding with agreement between persons who requested as well as who be requested, also meaningful of public involvement were discussed.
Public involvement was carried out at the Shirasuka coast in Chiba Prefecture in order to select measures against waveo vertopping over the seawall. Original plan to build artificial reefs off the coast was opposed by local fishermen because this coastal facility kills seaweed field spreading on the widespread natural reefs off the coast. Combination of construction of a retreated parapet and reform of crown part of gently-sloping revetment were proposed instead of the original plan of artificial reef. Many local people supported this plan. Process of the public agreement was clearly summarized.
The authors have been widely participating to the public agreement processes of the public works affecting the coastal environment such as coastal, port and fishing port construction works as a researcher or an engineer. Based on these nationwide, concrete experiences, roles and tasks of the researchers and engineers in public involvement of works related to river and coastal management harmonized with nature and environmental recovery are discussed comprehensively.
Although many artificial tidal flats had been constructed in Japan, there was not enough monitoring data that can prove the restoration of the natural environment after the construction of the tidal flats. Hiroshima Port and Airport Office at Chugoku Regional Development Bureau constructed three tidal flat as environment restoration projects in Onomichi-Itozaki Port area, Hiroshima, Japan. Total area of three tidal flats is c. a. 60 ha. After the completion of the tidal flats, geo-morphological change, sediment quality, benthos abundance, and sea-grass (Zostera marina) habitats have been monitored since 1984 to 2002. Especially, during FY 2000 to 2002, high biological diversity as natural tidal flats, abundance of many endangered spices, and 8 ha of sea-grass (Zostera marina) habitat restoration had been observed.
Reclamation of tidal flat is one of the most critical nature conservation issues in Awase area of Nakagusuku Bay, eastern seashore, Okinawa Island, southern Japan. The environmental assessment of the reclamation of Awase tidal flat ecosystems including seagrass bed with many endangered species, have not been thoroughly conducted through scientific background before transplantation of seagrass bed by government. It is necessary to conserve the tidal flat that the citizens, NGOs, government, specialists, and stakeholders sit at a round table to discuss and reach a consensus based on scientific data of the ecosystems.
The need to develop a new framework to bridge different societies relating to coastal environments is first discussed for comprehensive understanding of recent heavily deteriorated status of coastal ecosystems like tidal flats, seagrass/seaweed beds and coral reefs, and for finding propers trategy to restore them. A council established in 2001 April for multi-disciplinary cooperation in this line is then introduced with detailed description on its activities, including successive joint symposia. Finally the latest joint symposium entitled “Tidal flat ecosystem at risk-its status and restoration strategy” is referred in some depth to discuss direction towards desirable paradigm to realize comprehensive and integrated scientific approaches.
The special session “Evolution of Public Works in Harmony with Environments mainly in Tidal Flats” was planned to find out the future directivity of public works for environmental restoration. In the session, the history and the present condition of reclamation, preservation, and restoration of tidal flats were reviewed, and how the works should be in the future was discussed. Presentations and discussion by researchers, NGO and government officials clarified the importance of tidal flat conservation, and some issues such as social recognition, consensus making, and scientific argument on environment and technology.
This paper presents a summary of the special session “Land Reclamation at Seas.” The aim of the session lies on identification of technologies which allow us to construct man-made land environmental-friendly and economically. The session consists of two parts: one part is presentation of the papers regarding with land reclamation and the other part is a panel discussion among panelists presenting the papers. Presented are four regular papers concerningseveral essential reclamation technologies and five invited papers concerning large land-reclaimed projects taken place at various parts of Japan. Among various topics discussed, a shielding structure for disposal grounds is most discussed.
Long-period wave problem is selected as the theme of the special session on the design and the construction of maritimes tructures. Firstly, the basic properties of the long-period waves, such as the generation and propagation of long-period waves, the engineering problems on those and the countermeasures against the long-period wave problem, and its reflection on the design maritime structure at present are lectured. The panel discussion for the reflection of long-period waves on the design of maritime structures was opened. The practical problems in the design stage and the direction of the future research on the long-period waves were discussed.
In the special session for ‘Ecosystem Model’ demonstrated that there has been significant advancement in the use of time-dependent multi-dimensional numerical models for coastal environmental studies. In addition to themodel applications, these papers also addressed numerous aspects of numerical modeling of coastal environment, including numerical algorithms, process representation and parameterization, larvae transport, environmental assessment, and computer graphics as a output tool. Depending on the target processes of interest, one should select anumerical model that uses the appropriate numerical algorithms and incorporates the appropriate processes.
A directional spectral wave transformation model with random breaking in 3-D bathymetry was presented by the author in 2002 with introduction of a gradational breaker index into a parabolic equation. The model is presently revised with introduction of a secondary gradational breaker index for of negative seabed slope to account for wave decay in the trough zone of a barred beach. The revised model succeeds in predicting wave height variations across the surf zone as shown through comparison with field measurements in the Ajigaura Coast and the data of Duck 94 and Sandy Duck campaigns. The model is further applied for analysis of wave transformation by artificial reefs. With addition of a frictional damping factor, calculation yields good agreement with the laboratory and field measuremendt data.
This paper is intended to investigate the spectral characteristics of sea winds and wind waves on the Pacific coast. Time variations of the significant wave heights and periods have been also discussed in relation with time variations of sea winds in order to investigate mechanism of the growth of the wind waves. In the initial stage of the wind wave, high frequency components grow up and then the lower frequency components are developed. The linear relationship between the significant wave height and wind intensity has been confirmed for the swell propagating from far field. The boomerang-liked istribution has been found in the relationshipb etween the significant wave height and period.
Recently, the model of the third generation wave forecasting and hindcasting became highly accurate representing by WAM or SWAN. The forecast accuracy and the feature of them have already been studied at several locations in Japanese coast. However, these study points are located facing to open sea and only two or three typical anomalous weather conditions were studied. WAM has a lot of actual result of open sea wave forecasting and hindcasting though, there is not enough reports for such applications in inner bay water. This report explains the feature for forecast and hindcasting of WAM in inner bay water by adopting WAM calculation for 124 examples of anomalous weather during 49 years from 1952 through 2000 at MISHIMA-KAWANOE port located at HIUCHINADA offshore.
Extended Boussinesq equations with wave-current interaction are derived and a numerical model is developed in this study. It is difficult for a standard Boussinesq model to treat the effects of pre-existing current field on waves. The present numerical model can easily take ambient current conditions into account by dividing the flow velocity into the wave component and the current component. In order to investigate the performance of this model, some calculations are executed. Firstly, the results of the calculation are compared to the theoretical results of Brevic and Aas (1980). Only in the region of low ambient current, namely low effect of non-linearity, the agreement is good. Secondly, the wave blocking phenomenon is numerically simulated. Although the model cannot treat the wave breaking effect, the wave blocking is predicted to some extent.
It is important to estimate an influence of permeable breakwaters in a numerical simulation for multidirectional random waves. In this study, a proposed method for generating transmission waves has been applied to the time-dependent mild slope equation for random waves. Transmission waves was generated by the wave damping method. The relationship between damping coefficients and transmission coefficients has been investigated by numerical simulations for uni-directional irregular waves. The validity of the method has been verified through the hydraulic model test for multi-directional random waves.
This paper describes utility of measuring settlement system with magnetic-transmission type water pressure gauge. In this system, settlement data can be acquired on board as magnetic wave from the gauge. The electromagnetic wave has very low frequency and can transmit through seawater, sediment and the atmosphere. Therefore, measurement can be taken without cables and its guide even if the gauge is buried in sand. Moreover, this system does not obstruct dumping and reclamation work in contrast to settlement plate with steel pipe. A series of tests on utility of this system was performed in the construction site of the Kansai International Airport. In these test, influences of dumping work on accuracy of measurement and strength of electromagnetic waves were investigated. After successfully performing these tests, this system is now being used in coastal reclamation projects.
In recent year, the capacity of the disposal space of waste is running short. Accordingly, construction of new disposing site is needed. The standard of impervious structure about a disposal site was defined by the law 1999. However, with the past technology about impervious sea wall, it is very difficult to construct this type of structure meeting this law. Then, we proposed new structure and material about impervious sea wall, which maintains the performance of water interception over long period. This research paper reports the result of the field experiment about impervioussea wall structure with clayey water interception material.
The new airport island being constructed in the second phase is located 200m offshore from the first phase airport island. With a total area of approximately 545 hectares, the second phase airport island will require an approximately 13km extension to the seawall. The reclamation of the second phase airport island will make full use of the accumulated knowledge and technological expertise developed during the first phase construction, with the added advantages of new developments in measuring and information technologies. These will lead to minimizing the differential settlement and create a stable foundation for the airport facilities in as short a time as possible.
Laboratory examinations and numerical analyses were undertaken to clarify the deformation and strength behaviors of water proof sheet, applied at a seepage control structure in an offshore waste disposal site. Water proof sheet, used in this study, is made of Polyvinyl Chloride (PVC), which is mainly used in an offshore waste disposal site. Tensile strength measured on several temperature conditions decreased linearly with the increase of temperature. Degree of stress relaxation of PVC sheet was shown to be constant irrespective of the magnitude of strain, and we proposed the equation about stress relaxation behavior by five-element viscoelastic model. Relationship between tensile stress and strain was evaluated on different strain rate conditions. As the result, tensile stress became larger with the increase of strain rate in the range of small strain, however, in the range of large strain, gradients of stress-strain curves became same for all strain rate conditions. Creep behavior and the puncture strength using backfilling stone are now under examination, and we will construct a comprehensive model, including those time-dependent deformation and strength properties of PVC sheet.
Coastal disposal is becoming significant in recent years due to the difficulty of locating inland disposal sites. In designing coastal disposal sites, the performance evaluation of the seawall barrier is of great importance. The effect of tide on the contaminant movement in coastal disposal sites had not been considered in past studies, while water flow under the seabed can be affected by the existenceof tide. To evaluate the barrier performance of coastal disposal sites, the advective-dispersive transport of contaminant under the seabed was analyzed numerically for major seawall barrier structures under several conditions including the existence of semidiurnal tide. Tide showed considerable controlling effect on the contaminant leakage through the barrier.
Three-dimensional and two-dimensional experiments on deformation of submerged breakwaters are carried out to investigate the differences between their results. It is found that the three-dimensional deformation is featured by the accretion at the landward head of the submerged breakwater. Deformed profile of cross-section at the head of the breakwater measured in three-dimensional experiments is not the same as that measured in two-dimensional experiments due to this accretion at the head. In other words, three-dimensional experiments have to be conducted in order to investigate deformation in this area. Onshore water particle velocity above submergedbreakwaters measured in three-dimensional experiments is larger than that in two-dimensional experiments because the difference between mean water surface elevations before and behind the submerged breakwater in three-dimensional experiment is small.
Artificial reefs have been used to protect coastal erosion, and are now replacing detached breakwaters. Although constructions of the artificial reefs sometimes cause significant score around the reefs, the manuals for the design describe mainly on wave decay. An opening between artificial reefs shows typical scouring likea corn at the offshore of the middle of the opening. To estimate a topographic change, we need the distributions of water surface elevation and the bottoms currents. In this research, we investigated the ability of a fully nonlinear Boussinesq model around anopening with the eddy viscosity model for wave breaking. This paper shows that the numerical results have good agreement with experiments wave surface distributions and bottoms currents.
Artificial reefs have been constructed for protecting coast form erosion and for replacing detached breakwaters. The constrictions cause topographical change around them. Main sediment transport around an opening is bed load, but suspended sediment cannot be ignored. So the experiment using 3-ADV (Acoustic Doppler Velocity Meter) was carried out to measure the vertical mean velocity distribution at a center of opening. The result of experiment shows that the return flows direction was upward at onshore, and downward at an opening. The return flows turn alternately up and down. The amplitude of mean horizontal velocity was the maximum at the bottom. Closing to water surface, the amplitudes of velocity were getting to small.
In this study, the hydraulic model experiments on stability of armor blocks are carried out for sloping breakwater and artificial reef. Especially, the influence of incident wave characteristics and arrangement of armor blocks on stability of coastal structures is discussed. As the result, stability of armor blocks depends on the wave period and arrangement of blocks. And the mechanism of disaster damage on armor blocks is different from coastal structures. That is to say armor blocks are damaged by the uplift pressure due to return flow of swash waves in the sloping breakwater, but by the horizontal wave force from breaking waves on the artificial reef. Additionally, initial damage place and damage process are clarified experimentally.
This paper presents the result of hydraulic model experiments on the coefficients of wave transmission over a low-crown-height type artificial reef which is made of wave dissipating concrete blocks. The ratio between the depth from water surface to the top of the submerged reef and the incident wave height, R/HI, varies from 0.79 to 8.75. The relative width of the reef against wave length, B/L has a variation from 0.51 to 2.53. The wave-breaking limit, R/HI, lies between 0.8 and 1.3 for the above structure. The transmission coefficient, KT, decreases following an increase in B/L. The change of KT is small for a range of B/L larger than 1.6. With regard to the relationship between the ratio of wave height over block scale, HI/d′, and KT, KT decreases slightly parallel with increase in HI/d′, being proportional to increase in B/L. There is no significant relationship identified between Reynolds number, Re, and KT. Based on the above results, an empirical formula to assess KT is proposed, employing B/L as a parameter.
We started the seawall construction of the Tomari nuclear power station unit 3 from March in 2001. Before the construction, since it was necessary to reduce costs of the seawall, we tackled development of new type seawall. In this development, we tested several forms of seawall and investigated functions and improved weak points of seawall by hydraulic model tests, and finally developed the low crest seawall that fitted for field condition and made it possible to reduce costs. It was found by hydraulic model test using multi-directional random waves that wave overtopping quantity was within the permissible range inall place of the seawall, and the blocks were unstable though the wave pressure was low at the concave section, so we put the high specific gravity blocks to improve stability and miniaturize the caissons to reduce costs at the concave section. The seawall was nearly completed, we started the field survey to verify wave pressure characteristics.
Wave overtopping discharge of gently sloping revetment was evaluated in comparison with vertical-type seawall based on the experimental results given by Tamada et al. There are many cases that the gently sloping revetment is built in front of the existing seawall, because of the limitation of coastal land in Japan. However, this causes increase in wave overtopping over the revetment. This kind of application of gently sloping revetment must be avoided.
Authors proposed a non-wave overtopping type seawall (refer as Flaring Shaped Seawall: FSS) with a deep circular cross section. Through a series of studies, they had already confirmed that the FSS satisfies a non-wave overtopping condition with an extremely lower crown height in comparison with a conventional wave absorbing upright seawall. In this study, the reduction effects of both wave overtopping and water spray by the FSS were investigated through hydraulic experiments. And then, in order to reduce the water spray on the FSS effectively, we proposed a vertical wall attached at the tip of the FSS as a technical device. It was confirmed that the vertical wall effectively reduces the spray on the FSS, and the quantity of spray becomes smaller than that on the upright seawall.
The theory to evaluate the passive earth pressure that acted on the spike arranged in the bottom of the artificial reef was derived. The passive earth pressure of the spike was derived by introducing new coefficient Cv into the passive earth pressure theory of the coulomb and evaluating the 3-D shape of the soil wedge. The spike of an angle type and a cross type was examined in this research, the direction of the sliding and the length of the spike were changed, and the sliding resistance that acted on the spike was measured. As a result, new coefficient Cv greatly depends on the aspect ratio of the spike and it has been understood not to depend so much in the shape of cross-section and the direction of the sliding. The passive earth pressure of the spike can be presumed according to internal frictional angle of sand, and new coefficient Cv.
This study concerns the verification of the applicability of a Super Roller Flume for Computer Aided Design of Maritime Structure (CADMAS-SURF) to specially designed long-footing caissons in an area of standing wave phenomenon through a comparison of the results of the CADMAS-SURF analysis performed for the long-footing caissons with the outcome of previous experiments. In the study, a limited amount of existing hydraulic model test data was supplemented with the calculations made with the CADMAS-SURF and the scope of application of the wave pressure formula based on the finite amplitude standing wave theory to the long-footing caissons was expanded in respect of the depth-wave length ratio and the footing length-wave length ratio.
Long-term coastal changes at Nakatsu tidal flat was investigated by comparison of past aerial photographs and snap photographs gathered from the albums of local people. Geographical maps were also compared to study the changes during one hundred years of this area. Past coastal situation and utilization were recovered. These data are useful for the future planning of this area based on revised seacoast law.
This study attempts to manifes the present landscape value of Tokyo Bay Fort #2 through in-situ landscape survey and analogical analysis with the concept of ruinage in British Picturesque Gardens in the 18th centuty. The Tokyo Bay Fort #2 was constructed as a major military facility in Tokyo Bay Waterway in 1914. It experienced the Great Kanto Earthquake in 1923 and blast by US military after the War, and most parts have been demolished. Since it has two slender wings, each area shows its unique landscape characteristics composed of the vertical and flat nature caused from different types of canons'setting. Furthermore, we quested the potential possibility for the current landscape to take on such a new value as “Ruinage”, relatively comparing with adjacent military ruins (Sarushima, Fort #1, Kannonzaki etc) and citing the findings of author's former study in which the ruinage landscape in British picturesque gardens were categorized into four;(1) Eye Catcher (2) Jinen: Aesthetically Non-Intended (3) Inclination for Antiquity and (4) Ephemerality.
Today, ‘Public Involvement’ in the development of large-scale public works such as offshore airports has become very important. In this study, a questionnaire survey was done on the school children living near the coasts in order to get present and future scope of both sandy beaches and tidal flats. The school children were asked to answer to ordinary questionnaire and also to draw the picture on the desirable use of coasts. As a result, it has been understood that the children think that ‘playing’ is important on sandy beaches and ‘learning’ is important on tidal flats. It has been concluded that getting scopes of children through picture drawing is quite effective.
There are 37 main tidal flat in Japan, and developments that would cause changes in the natural environment have been taking place in 16 tidal flats. In order to develop, to use or to preserve these tidal flats, it is necessary to determine environmental values that they possess. This study presents results of questionnaire surveys using Contingent Value Method (CVM) to estimate monetary values of tidal flats. We ask to respondents amount of the contribution to “tidal flat preservation fund” for the Isahaya and Sone tidal flats. Willing to pay (WTP) values are obtained, and various biases which influence the results are considered. The WTP values of this study are also compared with those of other studies.
A floating offshore airport has been proposed in Tokyo bay to reduce its environmental impact on the ecosystem of the bay. A new airport called Umi-Hotaru airport is proposed in the south of the Kisarazu man-made island (Trans-Tokyo bay highway: Tokyo Wan Aqua-Line) located in the center of Tokyo bay. Numerical simulations of flow and water quality covering the whole bay were conducted to assess its environmental impact on the bay. To investigate the local impact of this airport on the near field, special attention was given on the environment of Banzu tideland located on east side of the airport. Its shoreline change caused by the new airport was simulated, and the impact on the habitat of benthos was evaluated. The new airport will little impact on the environment of Banzu tideland as far as this study. The results of this study must give us the basic information on the environmental impact of the new airport on the bay, though the further detailed environmental studies will be necessary.