In connection with crude-oil production of Sakhalin shelf, studies on behavior of spilled oil in icy seawater. In experiments used crude oil, it is hard to keep on invariable conditions because crude oil viscosities are influenced by temperature and evaporation on oil is proceeding rapidly in the air. In addition, it is dangerous to use crude oil due to its toxicity and inflammable in the components of evaporation. Thus, in the experiments on the behavior of oil spreading under ice floes and recovery method for spilled oil is included in variable constrained conditions.
In this paper, alternative materials of crude oil and ice sheet for experiments were selected by digging the interface between ice sheet and crude oil, so that the experiment method of recovery method for spilled oiland thebehavior of oil spreading can be carried out systematically and safety.

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If an oil spill were to occur under the sea in the winter drift ice season, the spilled oil would spread along the lower surface of the ice. In this case the spilled oil is thought to gradually settle in the cavities and gaps under ice sheets. Accordingly, the recovery of spilled oil becomes very difficult. However, the oil can be separated from those cavities by introducing an air layer between the oil and the ice floe. But these gaps between ice floes are usually thin and weak. This paper examines a characteristics of air layer which formed under the lower surface of the gaps of ice floes. The experiments on bearing capacity of ice between gaps of ice floes against the pressure of air layer and characteristics on heat transfer of ice and air layer were conducted. The experiments showed that the ice between gaps of ice floes could be stable against air pressure, and the air layer insulated the heat transfer through ice and saline so that growth of ice would be prevented.

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In cold region, the design ice load for offshore structures is often given by first-year ice ridges, it is important to obtain knowledge about ice ridge, especially consolidated parts, in designing offshore structures. However, the physical properties and strength of sea ice ridge appear to be much more complex than those of undeformed ice or level ice.
The authors conducted a preliminary series of tests (uniaxial compression tests) in the laboratory to investigate the strength and the physical properties of the consolidated part. In order to construct an ice ridge, cubic ice blocks of varies size (a) were place in the ice tank filled with salt water that had greater salinity than that of the ice blocks. After they were refrozen, using varies size core drill (d), we collected core test samples of varies sizes and various d/a ratio, due to combination (a) and (d). and then we examined its physical properties and its strength characteristics in considerations with the size effects.

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Ice Scour (Ice Gouge) is a phenomenon that occurs when ice comes into contact withseabed. Ice gouge has been reported to have caused damage to communication cables and water intake pipelines. Since oil and natural gas exploration projects in offshore areas of arctic seas are becoming popular, more care must be taken over the design and installation of oil pipelines in such areas in order to avoid accidents due to ice scour. It will be very important to acknowledge mechanisms (ice motions, sub-seabed conditions on gouge events). In addition to our previous tests (Kioka and Saeki, 2000), we have performed many series of model tests under various conditions. We revealed relationships between pore water pressure in the sand and bulldozing force due to velocity of the model keel, and we also prospected depression of model keel during scour events.

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Ice Scour is a phenomenon that occurs when ice comes into contact with seabed. Ice Scour has been reported to have caused damage to communication cables and water intake pipelines. It will be very important to acknowledge the mechanisms. We have performed a series of small-scale (1-g) model experiments. Furthermore, we performed a series of medium-scale model experiments on ice scour events at a sandy beach in order to try to determine the effect of scale. The model ridge-keel was placed in the sea and pulled at a constant velocity toward the shore by a crane, and the bulldozing force and the motion of the model keel were measured, Furthermore, a model pipeline to which a strain gauge had been attached was buried at a depth of 15-20 cm from the predicted scour surface, and stress and strain acting on the model pipeline during a gouging event were measured. We showed our mechanical model could be applied to scour events not only on a small scale but also on a medium scale. We also discuss similarity law between medium-scale test results and small-scale test results, stress and deformation acting on the model pipeline.

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Blockage by ice floes and freezing of the seawater in ports along the coast of Hokkaido, theonly coastal sea area in Japan that freezes over in winter, have serious direct and indirecteconomic impacts on various industries such as shipping and fishing industries. In order to devise strategies todeal with the problem of port closure in winter, the mechanism by which the water in the ports freezes mustbe elucidated. Elucidation of this mechanism and the establishment of measures to resolve theproblem of freezing in ports would be very beneficial for industries operating in such ports.
The aim of this study was to elucidate the mechanism of freezing in Otsu Fishing Port, aexcavatedtype fishing port in which the water freezes almost every winter, and to try to establisheffective measures for dealing with the problem of port closure due to freezing.

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Recently, the long-distance mud transport pipeline systems using a compressed air are utilizing in the field of marine construction works and coastal zone developments. This system is very useful for high density mud transport. However, previous studies of air-liquid two-phase flow have mainly focused on the flow deformation phenomena in short-distance pipeline. The purpose of this study was to clarify the mechanism of mud transporting pipeline system using a compressed air in the experimentally. This papers describe about moving velocity, pressure gradient, pressure fluctuations and passage period of slug flow in long pipeline. As the result of experiment, itwas to clarify that the rate of increase on slug velocity is remarkable at the end of pipeline and it was shown that the passage period of slug flow in long pipeline was controlled by quantity of liquid.

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Undesirable usage of gently sloping revetment was investigated taking the cases on the Kaike coast in Tottori Prefecture and the Kitanowaki coast in Tokushima Prefecture as the example. On these beaches, gently sloping revetment was built in front of the existing vertical seawall resulting in narrowing of natural sandy beach. The reason is due to the fact that construction works in order to enhance coastalenvironment are only possible in the narrow coastal preservation zone designated by law. This issue is summarized by the relationship between the locations of the shoreline, foot of sloping revetment and seawall. Correction method is shown.

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The irregularly mooring boats are becoming big troublesome problems with other commercial vessels and fisheries boats in harbors and rivers. The port authorities are planning to develop new marinas for the irregularly boats on private finance initiatives. However, the authorities are proceeding with the projects in confusion due to a lack of the information which constructing and operating scheme is best minimizing finance expenses of the public sectors over the life of the project contract.
In this paper the some number of key messages are shown, i.e. the public private partnership method which the construction costs are shared between public sector and private sector is best one for the value for money, and it is necessary for the Japanese government to attempt the PFI contractors as public sectors for theincome tax collection of the companies to avoid the tax transfer from local governmento national government.

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This study aims at planning of fishing port on the coast with big range of tide and coastaltidal flats, which obstruct fishing boat navigation on low water. As a result, we have proposed anartificial island fishing port with a connecting bridge, which would realize the navigation free on low waterand conserve the shape of coastal tidal flats.

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About 47% of land area of the earth is dry lands. Dry lands are found in areas where the amount of evapotranspiration is greater than that of precipitation. Desertification is the land degradation that occurs in dry lands as a result of various factors, including climatic changes and human activities. The effects of desertification are being felt in about 17% of the whole area of dry lands and the affected area is expanding. The major cause of desertification is human activities, paticularly current agricultural practices such as overgrazing, inappropriate agricultural land management, deforestation, and overexploitation of vegetation for domestic use (including utilization of trees for firewood). Behind desertification lie factors such as rapid population growth and poverty. Therefore, establishment of susutainable agriculture through improved technologies thata are mainly based on traditional knowledge, and reconstruction of socioeconomic systems which will give benefit to local people for combating desertification are necessary

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地震は古来災害で一番恐れられ, 古文書にも数多くの記載がなされている。我国において, 地震の記載が最初にあるのは, 日本書紀 (養老4年 (720)) 允恭天皇記の5年7月14日 (416・8・13) の河内地震である。それ以後, 記録されている被害地震は400を越えている。地震はその原因が判らず, 「地下の大なまず」の仕業にされ, 神業・祈祷・陰陽道などで天変地異として理解していた。しかし, 最近, プレートテクトニクス説で説明される地球科学の理論で, 地球内部での現象, 地震のメカニズム, 火山活動などが明らかにされている。
2000年春から, 北海道有珠山の噴火, 伊豆諸島の三宅島・神津島の地震活動と噴火, そして鳥取県西部地震を始めとする日本海沿岸地域に多発する地震と, 最近活発な時期に入ったと見ることができる。山陰地方では, 過去の大地震の発生, 微小地震の帯状配列と, 日本海沿岸に沿った地震活動がこの地域の特徴である。火山分布・地形分布などとの対比もこの形状と同じであり, 地下のいろいろな構造がこの傾向を示している。

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In recent years, offshore wind power systems are public attentions as the new frontier, because the cumulative capacities on land in Europe were considerably increased.
In our country, although the introduction of wind power generating systems on land were increased in the last decade, there are difficult problems inherent in establishing a large number of installation. Therefore, in order to promote offshore wind farms in Japan, this study assessed some issues of installing offshore wind farms based on the current state of development of offshore wind power generation systems in Europe.

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Over the last decade the wind energy technology has dramatically been developing to meet the needs of the times for clean and renewable energy resources and the attributes of offshore wind energy resource have beenreceiving increasing attention. Our goal in this paper is to raise some key issues that must be evolved in order to realize a large-scale offshore energy base. The concept outlined here is one of the important technological areas identified by the “Committee of Japan Ocean Industries Technological Strategy for the 21^st century”(Chairman: Prof. Koichiro Yoshida, October 1999 to March 2001) organized in JOIA (Japan Ocean Industries Association).
The authors expect that the considerations presented in this paper can invite further continuous investigation to realize the projection based on cost effective offshore wind energy technologies.

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It is important to promote the introduction of new energies that impose low loads on the environment. Wind power is viewed as a promising new energy source that is pure, clean, and inexhaustible. In the coastal areas, wind is not disturbed by structures and relatively stakes. These areas therefore, are suitable for constructing wind energy conversion systems. This report describes the design method of the foundation and the execution methodologies for offshore wind energy conversion systems.

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Wind energy for electric power generation was estimated around all over the Japanese coastal area. Observed wind data every 2 hours for four years at twenty-nine stations were acquired by using the Nationwide Ocean Wave information network for Ports and HarbourS (NOWPHAS) system. Results of the observed wind statistical analysis showed that wind characteristics on seas are much more suitable for the power plants than ones on lands.

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