As the ocean is vast and the ocean phenomena change quickly, the satellite remote sensing is considered to be very useful for monitoring the ocean. The remote sensing technologies are characterized by wavelength regions of the electromagnetic waves bing used. The remote sensing is generally classified into visible near infrared, thermal infrared, active and passive microwave remote sensings. The characteristics of the ocean observation by satellite remote sensing are explained and the ocean phenomena which can be observed by each remote sensing are descibed. The sea surface temperature, one of the important ocean phenomena, can be observed using the thermal infrared remote sensing. The active and passive microwave remote sensing are effective for monitoring the ocean owing to their observation capability under all weather condition. The satellite remote sensing data available for monitoring the ocean at present and in future are also described.
The Kansai International Airport is the full-scale, large off-shore airport, the first of its kind in the world. This paper presents, first, the analyses of the Kansai International Airport in terms of its planning and technology. It also proposes the concept of the off-shore urban airport which might effectively become the main stream of the future airport construction project in this country. Technical reports on major works of the construction of the Kansai International Airport are also included.
A wide areas breakwater, to oversee a spacious area inclusive of several f ishingports, will be constructed to secure “ calm”. Furthermore, the breakwater will duplicate as a farming zone to promote “fish farming industry” in the waters. Therefore, in this survey, plans and basic designs have been devised for a breakwater that can secure a “calm water area” for the safety of fishing vessels and retain “certain water quality” for its function as a fish farming zone, with the “slit caisson type” finally being proposed for the breakwater structure.
In order to promote coastal fishing and improve the residential environments of fishing regions, it is imperative not only to raise improvement standards for individual fishing ports and villages, but also to establish functional roles and relationships between fishing ports which are interdependent and mutually beneficial. The functional roles of fishing ports must also be developed on a regionwide basis. This document proposes planning methods for exploring the direction of fishing port improvements on a regional scale by regarding each prefecture as a regional improvement zone. The roles of individual fishing ports in each zone are also clarified.
Tokyo International Airport (Haneda Airport) is being expanded in order to increase the airport' s capacity, eliminate the noise troubles and utilize the man-made island as waste disposal areas. In this project, all of the facilities in terminal area such as the terminal building, the control tower, access roads and bridges are newly constructed on artificial island made by embankment in Tokyo Bay. To create good landscape architecture, almost all of facilities are well planned, designed and constructed. The processes of the study on landscape architecture in the planning, design and construction are described in this paper
The Port of Kuantan had been completed in 1978 by European contractor, immediately after which the steel sheet pile cofferdam type of quaywall began to suffer the excessive sliding and settlement. Furthermore, during monsoon season, the wave height in basin sometimes became more than 1.0m, causing difficulty and danger the berthing and loading/unloading of the ships. In this paper the remedial method of quaywall and layout plan of the breakwater by calmness analysis are presented, and the result of our examination for earth anchor test and wave observation during the construction are reported.
Characteristics of coastal zone in Ibaraki Prefecture are investigated from the comprehensive point of view of“protection”, “conservation” and “utilization” for a typical example. Regional characteristics of 7 subregions of this coastal zone are summarized and compared each other. Future plans of each subregion are proposed based on these regional characteristics. Furthermore, fundamental concepts for the utilization and protection of overall coastal zone of Ibaraki Prefecture are proposed, which are required for the optimal development.
Aerial photographs of coral islands in Maldives were taken to investigate the streak pattern developing on the shallow coral reef surrounding small islands. These streak patterns correspond well with the streamlines of the nearshore currents induced by wave breaking. The direction of the littoral transport was determined from these streak patterns. Beach erosion caused by the effect of the construction of impermeable jetties was investigated and plan ning method to prevent beach erosion was discussed.
In the planning of the shore protection facilities the harmony with the coastal environment should be taken into consideration as well as their protective functions and construction costs. However these points have not been analyzed yet and the data necessary for the planning are inadequate. In this study the examples of the coastal facilities in harmony with coastal scenery were gathered. 70 photos of the facilities were collected from the 68 coasts in Japan. These facilities were classified depending types, such as (1) vertical, mildly sloping and stepped type sea walls or revetments, (2) artificial beaches, (3) groins, (4) headlands, (5) detached breakwaters and (6) artificial reefs. The relation between coastal scenery and shore protection facilities is closely described in each type.
This paper proposed the constituent model for the arrangement of coastal structures in a fishery harbour. The model consists of the arcs of circle and ellipse and the line segment. In order to determine the aesthetic measure for the whole fishery harbour, the popularity of the constituent for coastal structures was evaluated by a questionnaire survey. The symmetrical elements impress us favorably. The curved shape is favorable. The rectangular structures, which are mainly shaped by means of right angles and line segments without symmetry, are common in Japan but artificially impressed.
The spring tide in the East China Sea on September 4, 1989, is simulated with coarse grids. As the open sea boundary conditions, tide are constructed from constituents at 24 stations along the boundary. The computed tidal current explains well the formation of sand bars at Chonggang. With finer grids, the tide in Hangzohou Bay and Yantze Estuary is also simulated, by using outputs of the simulation with coarse grids as the boundary condition. In Hangzhou Bay, tidal currents mostly form linearly oscillating flow, affected by the coastline boundary, while they form rotaing flow in the Yangtze Estuary.
Large scale reclamation projects have been planned and constructed in coastal waters such as Osaka Bay and Tokyo Bay. It is of importance that the scheme of impact assessment must be established from the view point of long-term and whole circumstances of bays. In this study, three-dimensional numerical experiments are carried for the environmental assessments of two hypothetical big reclamation of coastal waters shallower than 15m or 18m. The physical indexes for the assessment are Okinose residual circulation and the front phenomena. The results show that in the case of reclamation depth of 18m the front is significantly affected by project.
A new type artificial structure, in order to upwell the cold and eutrophic water from the sea bottom to the surface in deep sea, has been developed. Recently, some types of artificial upwelling generating structures have been proposed. Those structures can be seen as one of the coastal structures which are based on the sea bottom. The proposed new structure is a kind of the big mooring artificial wall in the intermediate depth of deep sea. It can make more significant upwelling flows around the structure in comparison With other types proposed last. And it aims to be constructed in very deep sea for its structural characteristics.
Three dimensional structure of nearshore currents is obtained by detailed measurements of velocity by Fiber-LDV using a plane wave tank. Vertical distribution of cross-shore velocity is similar to sum of uniform flow and velocity distribution of two dimensional wave flume. Vertical distribution of longshore velocity is nearly uniform flow. Velocity measurements of the upper reaches of trough level of wave are important, because vertical distribution of velocity changes rapidly at the nearly trough level.
The author and his colleagues have been engaging in the study to estimate ice forces on Multi Conical Legged Structures (MCLS). They constructed a method to estimate ice forces on MCLS and gained a partial succession. It was recognized that the method must consider effects due to non-simultaneous occurrence of ice failure. In this study, the author employed the Monte Carlo simulation to consider the effects of non-simultaneity and obtained a better correlation to experimental results. Methods to calculate design ice force and simplified method to obtain a first look estimation of ice force were also proposed.
Positive Utilization of floating ice is recommended for the construction of marine structures in the oceans of polar and subpolar regions. In this study, the main subject is to systematize the utilization methods of floating ice in the marine construction of sea areas with ice, In addition, with respect to shorttime loading, we report on results of systematic experiments on the improvements of bearing capacity and asfety as a traffic road when geotextile is applied, and with respect to long-time loading, we discuss the use of air mats to prevent ice deflection and flooding due to such deflection.
The Okhotsk Sea coast of Hokkaido is rushed by dtift ice. Sometimes aquaculture facilities and fishery resources have been damaged by the movement of drift ice. And they affect activities of port and harbor. It is required that ice control facility are constructed for decreasing their damages. When we design the Ice control structure the data about drift ice (size, thickness and concentration ratio) is needed. The authors observed drift ices at the Coast of Okhotsk Sea and clarified the distribution of ice size and the relation between size and thickness.
This is a report on the results of detailed experiments conducted to clarify: (1) the effect on ice floe control by the Sink-and Float-type Ice Boom (SFIB) and (2) the optimal sectional form of SFIB which may pervent SFIB from burying in sand when it is sunk. SFIB has a structure with a number of floats connected to a steel wire which is tied to piers at both ends. When water is injected into the floats, the boom sinks. On the other hand, when air is injected into the floats, the boom floats to the water surface and prevents invasion of ice floes into the harbor.
Sampling and laboratory soil test to identify the soil are common at the first phase of construction both onshore and offshore, but it is much more expensive offshore than onshore. In this paper an accoustic method for the identification of seafloor soil is proposed, which is not so accurate but simple and cheep. The sledge on which the ultrasonic transducer is mounted is dragged in the laboratory and the frictional sound pressure generated between the sledge and soil is acquired in the range of ultrasonic sound (30, 50, 75kHz). And then the empirical relation between the grain size distribution and the sound pressure is shown.
The undrained strength anisotoropy oLaluvial marine clay were investigated through a unconfined compression tests. In the case of the Kuwana clay and Amagasaki clay, the both ratios of qu and E50 of horizontal specimen to the vertical specimen are about 0.8, and the ratios of that of Tokuyama clay are about 0.6 and 0.5, respectively. The relationship between undrained strength and angle between axis of sample and horizontal is given as a function of Ip, qu and overconsolidation ratio.
The frequency response of mooring anchor plate embedded in the seabed due to a steadystate harmonic mooring force is numerically evaluated by taking the seabed characteristics into consideration. In an anchor plate-eabed interaction analysis proposed in this paper, the seabed is assumed to be a fluid-saturated poroelastic medium whose behavior is governed by Biot's theory of wave propagation, and the mooring anchor plate in seabed is assumed to be a flexible circular plate or a rigid one. The effects of both the stiffness and the mass ratio of anchor plate on the response of anchor plate are numerically investigated.
control to change the direction of ship for minimizing a long period mooring force. Distributions of stresses and pore water pressure in seabed around anchors are investigated by analyzing a frequency response of cnd bearing anchor due to ship motion. Considering the interaction between anchor and seabed, the feasibility of a double point mooring system are examined, and the effects of both, the stiffness and the mass ratio of anchor plate on the response of anchor plate are numerically investigated.
This paper concerns the centrifuge experiments on wave-induced instability of sand beds. A flap-type wave generator was developed for the use under centrifugal conditions. The quasi-standing waves were imposed on the horizontal deposits which were submerged into the sea of silicone oil with 50cSt viscosity. The pore pressure time histories indicated that the temporal liquefaction occured at shallow depths of a loose deposit. A one-dimensional analytical solution was derived to analyze the measured pore pressure response. The poro-elastoplastic solution, which incorporates the cyclic contractancy of soils, favourably reproduced what has been observed.
This paper aims at investigating experimentally the characteristics and mechanism of the local scouring around multiple large circular cylinders under wave action, in relation to the water particle velocity at bottom around the cylinders, and to the case of one cylinder. The bottom configuration change around multiple circular cylinders has a strong correlation with the spatial variation of water particle velocity at bottom, and, is revealed to differ from that around one cylinder. Finally, the local scouring location around multiple large circular cylinders is shown to be well predicted theoretically by diffraction theory.
Field observations on the nearshore currents and the formation of sandy beach around Lhohifushi island in Maldives were carried out. Aerial photographs of this small sandy island were taken to investigate the pattern of the nearshore currents induced by wave breaking on the reef. Beach situation around the island were observed. Coral sand produced by wave breaking at the reef edge is found to be gradually transported by the littoral drift caused by incident waves from SE, and on the lee side of the island a sand spit is formed. This continuous sediment transport was interrupted by the construction of the impermeable jetty, and the downcoast beaches were severely eroded. In order to solve these problems shore protection method considering the overall littoral balance of the island is important.
The effects of the course of typhoon on the design wave height are amined at two locations in the Osaka bay. The existing data ofe the ind-casted wave height are utilized. At Nada offshore near the bhay ead, the 50 years design wave height generated by the typhoons proceeding westside of the bay is larger than that by thpe typhoons oceeding eastside. At Kashii river offshore along the eapsrt coast, the esign wave height by those proceeding eastside is larger than that by those proceeding westside. This is opposite to predicted from the wind elocity difference between east and west halves of typhoon.
In this paper, the 3rd-order theory of the two components composite wave in the uniform depth is developed with considering the higher order modulation of wave frequency, and the nonlinear interaction of the wave is theoretically and experimantally discussed. As the relative depth is smaller, the wave steepness is larger, and the ratio of wavelengths of two fundamental waves in two components composite wave, n, becomes near 1, the nonlinearity is stronger. In particular, when n becomes near 1 like as 0.8 and the relative depth is larger, the bound waves with angular freqencies 2σ1-σ2 and 2σ2-σ1 (σ1 and σ2 are the angular frequencies of the fundamental waves) considered by 3rd-order wave theory cannot be ignored.
The estimation method of reflection coefficient is proposed. This method is the modified one which is proposed by Guza et al. and assmued to the linear long wave theory, and moreover, dealt with the three dimensional wave field, while Guza et al. dealt with the two dimensional one. The reflection coefficient calculated by present method was compared with it by the directional spectrum which is calculated by maximum entropy method. The agreement between the estimated value and it by the directional spectrum is satisfactory.
The phenomenon of wave reflection caused by breakw ater with vertical wall in the deeper depth than that of wave breaking point is a non-liner boundary problem, it has been exam ined experimentally using the water surface displacement in changes of vertical wall height. In order to get the data new digital water level recorder w as used to record the w ater surface displacement and the heights of wave crest and trough from the still water level are obtained respectively. As the results, it is found that the vertical wall in the water contribut to increase of trough level and the upper vertical wall from still w ater level contribut to increase of crest level of Partial Standing Wave.
Minami-Daito fishing port is the under construction from last three years. The port is going to be constructed by excavating the coral reef of Minami-Daito Island which consists of a risen coral reef, having area about 6km long and 5km wide. The maximum excavating depth reaches about 60m. Heretofore, some attempts were made to construct a fishing port or harbor. However, even those attempts had been ended in a failure due to the invasion of incoming big waves.Therefore, the method mentioned above has been adopted to construct the fishing port. In this study, experimental and theoretically, the characteristics of waves around the port are discussed. Consequently, it is clarified that the long period wave does important role in phenomena at inner side of the port.
Accurate estimation of wave set-up in wave breaking zone is be of great importance to the design of maritime structures in shallow water area. A new computation method applying the energy flux equation is proposed to estimate wave set-up, coastal currents and wave deformation. The estimated wave set-up and heights on an uniform slope agrees to an experimental result at shore boundary. In the comparison of field observation, the estimated error of wave set-up and heights is about 15% and 30% respectively at shore boundary. Therefore, this model can be applied to the estimation of wave deformation in shallow water.
Shoaling deformation of short-crested waves acting on the slope is investigated experimentally. Power and direction-al spectra, wave height and steady current velocity on the slope are compared among regular, uni- and multi-directional irregular waves. The application of the conventional formula proposed based on long-crested wave experiments is also discussed.
In the sea partically covered by ice, ice pieces are swaied by waves propagating from the open sea area, and hit the structures with the speed of order of wave motion. To evaluate this impact ice force, the experiments were performed using plastic plate instead of real ice to examine the followings. 1) Wave attenuation under the ice cover. 2) Wave velocity under the ice cover. 3) Transportation of ice pieces caused by wave propagetion.
The method of weighted average was proposed for the transmission coefficient of wave past the permeable structure with the core. The weighted average was applied to the significant diameter of void in the structure. Each widths of parts of the structure were used for the weights. A part of the structure was made of the same size of the armour units, that is, the core. The calculated transmission coefficients were compared with the test data in a 2-D wave tank. The ratio of calculated transmission coefficient to the obtained transmission coefficient was in the range of 0.8 to 1.2. The transmission coefficient were calculated by the equations the authors had been proposed for the wave in shallow water region.
Characteristics of a flexible-type submerged floating breakwaterwitha pressurized airchamber under wave action and wave transformations are investigated experimentally. As flexibility of the structure and floating motion depend on air pressureinthe air-chamber, decreasing, airpressure means to increase of membrane movement and floating motion. Since the dynamic motion generate radiation wave, wave transmission tends to be smaller in order to the interaction of the wave and incident wave. The type of the floating can decrease wave transmission relatively.
In this paper, the wave deformation by and the wave force acting on three large circular cylinders are examined experimentally and theoretically, in relation to the case of one- and two cylinders. The wave profile around the cylinders and the wave force acting on them vary, according to the incident wave height, period and propagation direction, and the distance of the cylinders, and they are quite diffrent from the cases of one or two cylinders. The wave deformation and the wave force are shown to be well predicted theoretically by diffraction theory based on the boundary integral method using a vertical line wave source Green's function.
Recently, it is feared that enclosed sea areas are contaminated by industrial and household drainages. For the purpose of the water quality improvement there is a method to accerate the seawater exchange between the bay and the open sea by using the cooling water intake and discharge of the steam power station in an enclosed sea area. In this paper, the effects of cooling water on the sea water exchange are studied experimentally and numerically. As a result, the contribution of cooling water on the sea water exchange is estimated quantitatively. And the adaptability of the 3D numerical model used to simulate a sea water exchange is evaluated by comparison of numerical results
Being situated in Northwest Kyushu, Sasebo Bay is connected with the open sea (East China Sea) and also connected with typical enclosed bay named Omura. Especially, The Omura Bay has 53 small and medium size rivers around its coast, which discharge some materials polluting the bay such as sewage, industrial effluents, agricultural fertilizer, ect. All these materials make the bay overenriched with nutrients and this has been well known as cultural or man-made eutrophication. Therefore, water quality controlling and monitoring activities, recently, are inevitable. In this paper, we tried to research tidal current from the open sea to Omura Bay in other to obtain elementary data for Omura Bay's water purification using the remote sensing techniques. The field survey was carried out at three points with thermal infrared camera. And satellite data called Landsat-5/TM were applied to explain field data.
A theory is developed for estimating the wave transmission, wave reflection and wave forces for a spiral-fibered, highly porous barrier used well for submerged biofilter. Theory is based upon the low of momentum flux and energy flux conservation and Morison's equation. The solution is compared with result of model tests, in case of upright wave-absorbing-type and floating wave-absorbing-type, and agrees well.
The triangular sand bar which often exists around the river mouth has the suitable topography for surf-riding. The delta type artificial reef which imitated this triangular sand bar was newly designed for the shore protection structure. In an experimental wave basin, the characteristics of the wave breaking, the wave runup, the littoral current and the sand drift were studied. As compared with thegroins, the delta type reef has the superior property in the sand drift control and the waverun-up height decrease.
Considering the phase relationship between the diffracted waves and radiated w00aves by a floating breakwater, an effective method of reducing incoming waves is newly proposed. It was clarified that the phase relationship between the two waves becomes out-of-phase under which the floating breakwater shows a resonant response to wave forces. Consequently transmitted waves can be reduced effectively under the resonant conditions. It was also found out that the resonant condition lasts for a wide range of wave frequency if the floating breakwater has a comparatively deep draft, such as a floating body with deep curtain walls.
Experiments are carried out in a wind water tunnel. In this paper, wind-waves mean the newly generated waves behind the breakwater by wind. Horizontal distributions of wind velocity and wave height behind the breakwater are obtained. The useful type of wind-fence and the useful setting position of wind-fence on breakwater are found.
Flapboard breakwater is a newly developed structure made up of rows of elastic boards with high rigidity. Reducing the energy of the incoming waves due to reaction forces and swing of the elastic boards, this breakwater creates calm sea area. The 3rd District Port Construction Bureau is now carrying out fundamental hydraulic model tests to examine the functions and characteristics of this newly developed breakwater. This paper reports the hydraulic property of this flapboard breakwarter obtained through the hydraulic model tests.
A gentle slope wave energy dissipating structure with water cushion was constructed at Mitoyo, Kagawa, Precture, in 1984, on land reclaimed along the shore in order to prevent sea wind damage to farm products. This structure is based on the hydraulic model test. To new smaller structure types with water cushion have been constructed as a result of this observation and the the hydraulic model test twice. This thesis discusses the difference between the wave overtopping phenomenon of the hydraulic model tests and the field observation. The thesis concludes that it is difficult to represent the actual wave overtopping phenomenon from the hydraulic model test based on Froude Similitude.
Wave reflection from a slit-type breakwater having plural rows of cylinders as front walls is studied theoretically and experimentally. In the theoretical study, a method of matched asymptotic expansions is developed with the aide of a perturbation method. The energy loss due to flow separation near cylinders is modeled by introducing a complex blockage coefficient. The theories are compared with laboratory data for a model of the slit-type breakwater having two rows of square cylinders.
A numenical model is developed to calculate the vertical displacement of flexible floating structures. This model is based on the Finite Element Method (F. E. M.). In the case of displacement caused by static load, the results of F. E. M. agreed with those of strict solution. The movement in waves is also calculated by numerical integration of the equation of motion based on F. E. M. Wave-exciting forces and wave making resistance forces upon elements are calculated from velocity potential.
In some isolated islands far from the Japanese main island, port facilities like a quay, sea wall and breakwater have not been completed. A mooring buoy is widely employed to moor a vessel at the quay walls facing to the ocean. The joints of the buoy-mooring chain may be broken off when large impulsive tensions are exerted by attacks of large waves. The impulsive mooring tension can be reduced by applying an elastic'rubber chain'as a part of the buoy mooring chain. The tension may become less in case of soft ground.
A new type of traffic terminal has been constructed at Yokohama bay recently. It is composed of 2-storied house on a floating pontoon and moored by pile-fender system. There are ticket counter and waiting lounge on the first floor and restaurant on the second floor. Since the floating type was applied to the passengers terminal station for the first time in Japan, We examined the relation between comfortability and motion of the terminal. Several interesting results, such as people who are easy to get seasick have tendency to estimate the motion of the structure excessively, are obtained.
Wave pressures acting on a caisson covered with armor units are investigated under wave attacks of which wave heights are greater than a design wave height for the armor units. Damage levels of the armor layer were measured to discuss change of the wave pressure profile due to the development of the armor layer. No significant increase of the wave pressure is found when the damage level is less than 10 (damage rate based on Hudson formula is less than 34%). When the damage level is greater than 10, the wave pressure over the still water level acting on the. caisson drastically increases.
Goda's formula is standard expression for the wave forces of composite breakwater, but it underestimates on condition of the impact breaking waves. On the otherhand, Takahashi et al (1992) introduced the coefficient of impact breaking wave forces (ai) into Goda's formula. In this paper, we study on the characteristics of wave forces on the breakwater discontinuous wave dissipating blocks. On that condition we confirm that impact breaking wave forces work on, and show the introduction of ai with regard to estimation of wave forces.