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鷲見 浩一, 牛木 賢司, 水谷 法美, 岩田 好一朗
2001 年 17 巻 p.
293-298
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
This study investigates experimentally the wave-induced flow field formed on an artificial tidal flat. At the offshore edge of the tidal flat, submerged dike are often constructed to protect sand erosion, which affects the flow field. Hydraulic model experiments have been conducted to investigate the flow distribution and wave height distribution. It is found that circulating currents are formed around a submerged dike. The circulation flow is revealed to depend on the wave steepness and relative opening width of the dike to the wavelength. Results also show that the strong flow is formed in the vicinity of the opening of the dike, which suggests the local scour and countermeasures against the scour may be necessary.
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中村 孝幸, 竹本 剛
2001 年 17 巻 p.
299-304
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In order to reduce wave heights in a harbor, an artificial trench installed in front of theharbor entrance was newly proposed as alternative works of detached and offshore breakwaters. Based on the wave refraction mechanism by water depth variations, change of wave propagation direction by the artificial trench is realized. Several factors regarding artificial trenches, such as locations, sizes, plane figures and so on, were examined theoretically by the numerical method of analysis. For the comparison, effectiveness of a rectangular resonator for harbor tranquility was also examined. It was confirmed that artificial trenches with a circular and rectangular figures are effective for reducing incoming waves to the harbors, especially for normal incidence of waves to that entrance.
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中村 孝幸, 村上 浩司, 国本 栄一
2001 年 17 巻 p.
305-310
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Recently, it has become known that multi directional and irregular natures of incident waves are important for estimating wave sheltering effects by maritime structures, such as wave diffraction effects about a harbor entrance gap. In this study, concerning with variations of wave reflections and transmissions about harbor breakwaters with wave period, the harbor tranquility for the incidence of multi-directional and irregular waves was examined extensively. The vertical line source Green's function method was basically used for the numerical computations. Extension of the method to the permeable boundary conditions was briefly introduced.
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玉田 崇, 井上 裕規, 井上 雅夫
2001 年 17 巻 p.
311-316
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The purpose of this study is to clarify the characteristics of wave overtopping on gentle slope-type seawall. Therefore, the experiments on wave overtopping by irregular waves were carried out for gentle slope-type seawalls. Using the results, the diagrams for the estimation of wave overtopping rate were proposed for the gentle slope-type seawalls with 1: 3 and 1: 5 slope. And, these diagrams were compared with the diagram for upright seawall by Goda et al. As the result, by comparing for the upright seawall from the viewpoint of the wave overtopping prevention, the gentle slope-type seawall clarified the advantageous range in the relationship between relative water depth and relative crown height of seawall.
In addition, the effects of sea level, wave height, crown height of seawall, wind, and etc. on the timerelated variation of wave overtopping rate were examined using the existed experimental results.
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下迫 健一郎, 鈴木 高二朗, 黒田 豊和, 大木 泰憲
2001 年 17 巻 p.
317-322
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The recent utilization of reclaimed land to provide large-area, man-made islands, e. g., those used for airports, has necessitated their construction in relatively deep seas, which naturally requires them to be surrounded by seawalls that are directly exposed to strong waves since no protective breakwaters are present. Consequently, failures frequently occur during and after construction. Especially, the breakage of backfill stone and geotextile sheet, which caused by wave overtopping and transmitting wave through rubble mound during the construction, result in landusage problems and expensive long-term maintenance requirements.
We conducted a hydraulic experiment in order to investigate the breakage mechanism caused by wave overtopping. The pressures and velocity acting on the part of backfill stones and geotextile sheet are measured. The impulsive pressures and consequent transmitting waves acting on the slope of backfill stones lead to the breakage of geotextile sheet and collapsing of backfill stones.
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中村 孝幸, 西川 嘉明, 小野塚 孝, 加藤 孝輔, 神野 充輝
2001 年 17 巻 p.
323-326
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
It has become known that a curtain-wall type dissipater of reflected waves from vertical sea walls and breakwaters is more effective for comparatively long waves than the conventional perforated walls and breakwaters. The dissipation mechanism of reflected waves is to enhance vortex flows around a vertical barrier by the use of piston-mode wave resonance in the water chamber. However, for the sea with large tidal difference, it is concerned that effectiveness of the reflection dissipater may vary significantly with tidal levels because the draft depth of the vertical barrier changes with tidal levels.
In this study, at first, variations of effectiveness of a curtain-wall type dissipater with tidal levels were clarified by both the physical model test and theoretical study. Secondly, in order to overcome such difficulties resulted from varying tidal levels, two different counter measures were proposed. Effectiveness of these measures was also examined theoretically and experimentally.
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中村 孝幸, 高木 伸雄, 中山 哲厳, 河野 徹, 森田 嘉満, 菊地 一郎
2001 年 17 巻 p.
327-331
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In order to mitigate secondary effects caused by high reflection waves from a conventional curtainwalled breakwater, a new type of breakwater consisting of two different walls was proposed. One wall is an impermeable curtain wall and located on the shore side of the breakwater. The other is consisted of an array of inclined plates with the same gap and located on the offshore side. For the practicalapplication of the new breakwater, the influence of a super structure on the performance was examined extensively. Furthermore, presuming the sea area with significant tidal difference such as the Seto Inland Sea, effect of water levels on the performance of the breakwater was also clarified. The dissipation mechanism used here is to enhance the generation of vortex flows from the plate-array front wall. By using the Helmholtz mode wave resonance between the two walls, enhancement of the vortex flow is realized.
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斎藤 武久, Guoping MIAO, 石田 啓
2001 年 17 巻 p.
333-338
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The appearance of resonant phenomena in which the resonant force spectrums appear with sharp peaks due to interaction between waves and two rectangular cylinders with small gap has been indicated both numerically and theoretically in our previous paper
1) . This resonance should be considered in the construction of large offshore structure connecting with many rectangular unites.
This paper presents more details of the numerical calculation methods and the theoretical derivation, and newly shows the following characteristics of resonant phenomena; 1) The resonant phenomena appear only in the cases that two rectangular cylinders come very close. Especially, in the case of square cylinders, the resonance dose not happens when the gap width is longer than 8 percent of the gap length. 2) Non-dimensional resonant wave numbers are regardless of incident wave angles.
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董 勝, 李 華軍, 高山 知司
2001 年 17 巻 p.
339-344
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The major objective of this study is to experimentally and theoretically investigate the characteristics of rectangular Tuned Liquid Damper (TLD) under wave excitation. An obvious engineering motivation for this study is to explore the applicability of TLDs for suppressing the structural vibration of offshore platforms. The structural model used to perform experiments is scaled according to a full size platform by matching their dynamic properties. Rectangular TLDs of different sizes and water depths are examined. By observing the performance and the behavior of TLDs through laboratory experiments, the influence of a number of parameters is investigated. In an analytical or numerical study, a mathematical model that describes the nonlinear behavior of liquid in TLD and the interaction between TLD and structure is prerequisite. Validity of the mathematical model to simulate the behavior of liquid in TLD and TLD-structure interaction has been evaluated based on the experimental results.
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森田 知志, 中村 孝幸
2001 年 17 巻 p.
345-350
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The three dimensional source distribution method is a popular technic to estimate hydrodynamic pressures on offshore structures during earthquakes. However, because only series-form expression of proper Green function was available, it takes long CPU time for accurate calculation. In this paper, an alternative integral-form expression of Green function is derived and its efficient way to calculation is presented. Resultant acting forces on circular and submerged rectangular cylinders vibrating horizontally under the effective dimensions of cylinders are also presented.
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森田 修二, 出口 一郎, 尹 晟鎭
2001 年 17 巻 p.
351-356
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The authors have already shown that breakwaters with slope channel and step channel effectively reduce transmitted wave height when compared with a straight channel, and the flow rate through the breakwater with channel can be estimated from the non-linear Darcy's law.
In this study, the authors examined the ability of the breakwater with channel to exchange water in the model harbor in a three-dimensional wave basin. The authors also proposed numerical model for predicting the rate of water exchange in the harbor and the applicability of the proposed model was also examined using experimental results. The time required to change whole water in the harbor can be estimated from the water volume in the harbor, the representative longshore current velocity, and the opening ratio of the channel in the breakwater.
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藤田 孝, 永田 修一, 岩田 節雄, 新里 英幸, 武田 純男
2001 年 17 巻 p.
357-362
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
New permeable type breakwater with low wave reflection performance is developed. This breakwater consists of a slit wall and reservoirs, in which L-type impermeable walls are set up, in front of a permeable vertical wall.
As the results of hydraulic model tests on the wave reflection, it is found that the breakwater has very low wave reflection performance for wide frequency range. Furthermore, the experiments on the water exchange performance are carried out, and it is found that the breakwater is effective in water quality improvement of an inner bay.
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高山 知司, 吉岡 洋, 大栗 剛, 村山 英俊
2001 年 17 巻 p.
363-368
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
We investigated how the water exchangeable breakwaters promote seawater exchange between a harbor and its outer region using numerical simulation. The flow was calculated with nonlinear baroclinic two and three layers model taking into account the flow through a water exchangeable breakwater. In this model, we express a breakwater as a line on the grid space without thickness. In order to calculate the water level at inside and outside of a breakwater, water level was defined with 4 division at 1 point. The mass flux through a water exchangeable breakwater is calculated by an energy equation of non-steady flow through a tube. Characteristics of seawater exchange at a harbor were investigated by many watef particle trajectories. Distribution of water residence time and variation of exchange ratio were evaluated. Dominant horizontal oscillating flow had little effect for water exchange; therefore, residual flow including vertical component played on important role for it. When exchangeable breakwaters were arranged to promote tidal residual circulation, water qualities of the harbor was improved effectively.
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重松 孝昌, 新枦 豊, 小田 一紀, 熊谷 裕児
2001 年 17 巻 p.
369-374
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The aim of this study is to recover water quality in enclosed water. For achievement of this aim, this study proposed a flexible training jetty as a structure hastening water exchange and promoting fluid motion in enclosed sea Some experiments for investigation of effect of the flexible training jetty are carried out and the results on the effect of the equipment angle and location of the training jetty on fluid motion in enclosed water and on water exchange are presented.
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清野 聡子, 宇多 高明, 塩崎 正孝, 後藤 隆, 黒木 利幸, 中村 利行
2001 年 17 巻 p.
375-380
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Field observations of the river mouth bars in Nakatsu tidal flat were carried out in view of aptitude of spawning site of horseshoe crab
Tachypleus tridentatus. Seven locations were selected based on the topographic features relevant to spawning site. Out of these locations, larval horseshoe crab was found around the Kakise and Maite river mouth bars. Topographic features of each river mouth were summarized. Preservation of river mouth bar is necessary for the protection of rare species.
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渡辺 国広, 清野 聡子, 宇多 高明
2001 年 17 巻 p.
381-386
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Impact of the construction of seawall on the backshore to nesting of loggerhead turtle Caretta caretta was investigated at the Kamouda coast in Eastern Tokushima Prefecture. Emergence number of sea turtles rapidly decreased after the construction of seawall on the backshore, where was the accumulation zone of wind blown sand and partly covered by vegetation. The reason is due to the fact that sufficient consideration of coastal environment was not taken into account in the coastal planning, because of lack of idea in the old seacoast law. Several measures to improve this situation are proposed.
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市村 康, 松原 雄平, 中村 幹雄
2001 年 17 巻 p.
387-391
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The purpose of this paper is to develop an ecosystem model by using cell automaton (CA). First, we simulated the distribution of
Corbicula japonica prime for a long term, and then considered the change in the distribution by the change of environmental factor. Our model is applied to Shinji Lake in east part of Shimane Prefecture.
The observation results were compared from distribution with the calculation result. The result showed a comparatively good agreement. It was able to be reproduced the distribution of the
Corbicula japonica prime in an extremely high density in the coast region. It has been understood that the change of the
Corbicula japonica prime has strongly received the influence of the change of an environmental factor.
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親泊 正孝
2001 年 17 巻 p.
393-398
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
To obtain a more accurate evaluation of strength, of coral gravel soil, engineering properties of that material were compared to soils of another group. Samples taken near coral reefs contain more gravel than those soils, and N values for coral gravel soil are lower due to less sand content. Results of biaxial UU-tests show some larger angles of internal friction in the samples of another group compared to zero degrees of angle in common clay soils using the same test. Results of triaxial CD-tests seem more credible than those of UU-tests in evaluating shear strength of coral gravel soil since this material is considered adequate as an intermediate soil. Triaxial CD-tests further demonstrate that coral gravel soil could be affected by the cementation effect.
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八木 典昭, 目見田 哲, 寒沢 智, 新幸 弘行
2001 年 17 巻 p.
399-404
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
A series of hydraulic model experiments are conducted to investigate the stability of armor units using SEASUP concrete block for discharge channel mound in the surf zone. The effect of wave breakig on the stability of the block is noticeable. The stability of the block is influenced by the water velocity (V
max, V
1/10) on the mound.
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秋山 真吾, 池谷 毅, 今藤 久夫, 高橋 忍, 石川 芳一
2001 年 17 巻 p.
405-410
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The conventional method used for covering shore protection by armor stones needs not only much time for processing stones but also many divers for averaging the rubble mound, setting up and leveling stones for armoring, thereby postponing work period and leading to rise of cost.
So we have designed a new method called filter-units in place of armor stones and performed hydraulic model tests to make clear those characteristics. The filter-units consisted of small stones and wrapping nets, have abilities of reducing work period. In this paper, we firstly explain the characteristics and the construction methods of filter-units. Secondly, we detail the result of the hydraulic model test. It was found out that filter units have excellent flexibility and suitability for waves equal to that armor stones have.
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小泉 哲也, 小椋 進, 橋本 雷士, 西村 正, 金田 研一郎, 森川 高徳
2001 年 17 巻 p.
411-416
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The weight of the armor block on the mound of the breakwater covered with wave-dissipating blocks might be smaller than that of the breakwater without wave-dissipating blocks, however the fit weight has not been studied so much. Therefore, the water velocity around the armor blocks and the damage rates of the armor blocks, of the breakwater covered with wave-dissipating blocks are studied in experiments and are compared with those of the breakwater without wave-dissipating blocks. Additionally, the diagram giving the fit weight of the armor block on the mound of the breakwater covered with wave-dissipating blocks for an allowable damage rate of 1% by using the Ns value is proposed.
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早川 哲也, 森 昌也, 梅沢 信敏, 土井 善和, 遠藤 強
2001 年 17 巻 p.
417-421
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In constructing ports and harbors, the Eco-friendly function has been recently added on coastal structures in Japan. As leeward step with a sloping breakwater provides the suitable condition for seaweeds, it was reported to effective construction in formation of seaweed forest. However, leeward step must be stable against wave overtopping, it needs to be covered by armor units.
In this study, hydraulic model experiments clarified fluid motion occurred by plunging of wave overtopping, and the design method of armor unit was proposed.
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島田 潔, 吉村 正, 杉本 達彦, 五十嵐 和之, 宮内 勇児, 大野 邦彦
2001 年 17 巻 p.
423-426
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
A model experiment is conducted for a water-exchanging breakwater caisson to confirm usefulness of the devices at the outlets of exchanging water in controlling jet flow. Inclined pipes installed inside the caisson wall show satisfactory performance without reduction of exchanging water quantity. On the other hand, hoods, which are attached to the outlets, obstruct the jet flow and reduce the exchanging water quantity, although they curve the jet flow noticeably. Theoretical consideration is satisfactorily done with respect to the effect of tide and incident wave height on transmission coefficient, assuming that pulsatingjet flow generates transmission wave.
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宇多 高明, 西村 晋, 渡辺 宗介
2001 年 17 巻 p.
427-432
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Field observation of the Manly Beach in the suburb of Sydney in Australia was carried out to investigate coastal zone environment. Coastal zone in this area has a much better environment compared with the Japanese coast, much of which is covered artificially by concrete blocks. One of the utilizations, which is new in Japan, is the natural pool built at the corner of the pocket beach. This is a good idea in order to create safe, natural recreational zone for swimming and it may be introduced in Japan. Improvement method in building gently sloping revetment is discussed.
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古屋 温美, 関 いずみ, 松本 卓也, 中村 誠, 長野 章
2001 年 17 巻 p.
433-438
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The Hokkaido Marine Vision (MV21) has been formulated as a long-term plan for improvement of fishing villages in Hokkaido. To implement MV21, preparing its follow-up program and examination of newly raised issues are required. Also, concurrently with the formulation of the MV21, seven model areas are planned. To implement the plan for these areas, anticipated issues for each area will be followed-up, and new issues areassessed. Furthermore, the benefits of a new ocean-use project, which is currently under planning for promotion of these model areas, and the effects of the implementation of the MV21 on each model area are examined.
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上田 真寿夫, 大久保 友美, 清野 聡子
2001 年 17 巻 p.
439-444
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Surfriders are watchers of ocean environment. Almost all around the year, they spend a lot of time in the water and observing changes of coastal environment. Therefore, they can play a role of the keeper of the coast. Surfrider Foundation Japan (S. F. J.) is the NGO and a satellite of the global network of the Surfrider Foundation which is dedicated to the protection of the world's oceans, waves and beaches, through conservation, activism, research and education. It has collected many information and knowledge of coastal management and environmental crisis through its network. Especially, it has expressed objections on the coastal civil works and development in Japan. Recently, it comes to propose alternative plans and systems to the local and national government.
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淡輪海水浴場の事例研究
島田 広昭, 井上 雅夫
2001 年 17 巻 p.
445-450
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
The purpose of this research is to establish the construction guideline of the artificial beach considering the human factor. Then, the results of consciousness investigation for the user of the Tannowa beach which was an artificial beach created about 20 years ago were shown, and the evaluation of artificial bathing beach by the user was examined.
As the result, it was possible to clarify any following fact. 1) The utilization of the beach diversified for recent 10 years. 2) By constructing the approach road to the beach, the user distribution in the beach was unified it would be able to be utilized from the double end. 3) When about 20 years pass after the construction, the users who know that this beach is an artificial one decreases greatly. 4) The total evaluation for the beach of the user improves about 15% in comparison with the evaluation about 10 years ago.
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高橋 敏彦, 沼田 淳
2001 年 17 巻 p.
451-456
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Beach profile changes in front of the gentle-slope sea dike and the damage of dike with them were studied experimentally by using the regular and irregular waves. Beach profile changes caused by irregular waves becomes smaller than that by regular waves. It will be considered that the beach profile changes are smoothed in general, because the wave breaking point for irregular waves is different every one wave. In the case of regular waves, although the damage of dike progresses gradually as a time of wave action becomes longer, the damage becomes early with increasing dike slope. On the other, in the case of irregular waves, the damage of dike did not occur within the limits of this experiment.
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渡辺 宗介, 宇多 高明, 芹沢 真澄, 清野 聡子, 三波 俊郎, 古池 鋼
2001 年 17 巻 p.
457-462
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Theoretical solution of shoreline change was applied to the Kujukuri, Misawa and Fuji coasts, and the coefficient of littoral drift was evaluated and compared. Aerial photographs were read to investigate shoreline changes on the updrift side of Katakai fishery port on the Kujukuri coast, where southward littoral drift dominates. Observed shoreline changes were well explained by the theoretical solution. The same method was applied to the Misawa and Fuji coasts, and coefficient of littoral drift on each coast was compared.
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阿部 光信, 佐々木 政秀, 石井 敏雅, 安田 勝則, 小池 雄一郎, 宇多 高明
2001 年 17 巻 p.
463-468
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
An analysis of beach deformation based on the long-term monitoring data at the Hirono coast in Fukushima Prefecture was carried out in order to consider measures against beach erosion and siltation in a port. The contour line change model was extended to predict topographic changes in the sea area with exposed rocks. The model was improved by considering spatial change in the depth distribution of longshore sediment transport rate based on the field observation.
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宇多 高明, 口石 孝幸, 見附 敬三, 加藤 憲一, 谷口 丞, 赤松 直博
2001 年 17 巻 p.
469-474
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Three dimensional predictive model of beach changes with berm formation under the action of longshore sand transport was developed by applying the contour line change model. On the Toban coast, beach nourishment using gravels was carried out in 1990 and 1991, and subsequent beach changes by longshore and cross-shore sand transport was measured. Based on these field data, a new model to predict three dimensional beach changes with berm formation was developed.
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海洋性温泉都市別府の写真資料を読み解く
平野 芳弘, 清野 聡子, 宇多 高明
2001 年 17 巻 p.
475-480
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Restoration of coastal utilization type was carried out based on old photographs showing coastal hot spar in Beppu City in Oita Prefecture. This city has been historically famous for hot spar gushing out at the sandy beach. This hot spar was named ‘sand spar’ because people were buried under the surface of naturally heated sand. It was only used in low tide level. After the bath, they could bathe seawater at the shoreline. Now this type of natural recreation disappeared. In order to consider future coastal utilization of Beppu City, this information may give a new standpoint.
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角本 孝夫, 太田 慶生, 清野 聡子, 宇多 高明, 澤藤 一雄, 藤田 則康
2001 年 17 巻 p.
481-486
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Long-term change of Ohata fishing port, famous as a landing port of squid in northern Honshu, was investigated by data-mining method of past photographs showing various activities at the port. Harbor structures have been constructed responding to the increase of landing of squid. However, when these infrastructures were completed, the amount of catch of squid largely declined, leaving large-scale harbor structures. In order to create sustainable community of this town, it is necessary to recover natural environment in the past Ohata having abundant resources of fish and shellfishes. Several measures useful for this are proposed.
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石田 健一, Frank CHOPIN, 三国 成晃
2001 年 17 巻 p.
487-492
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In an arena of coastal-zonem anagementt he present researchd escribes, an attempt to enhance planning capacity for planners from various developing countries and to generate lessons by doing so. Capacity development program was carried out targeting ten participants from Africa, Asia, South Pacific and Latin America. Participatory planning and stakeholder analysis were applied. Each participant established own-problem-based solutions and development strategy in their respected coastal zone with the assistance of facilitators. The attempt was highly applicable and proved to be useful for capacity development in fishery and participants also highly recognized and evaluated usefulness of this approach. As a result of the trial the consideration for developing seed project was also generated.
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高橋 重雄, 姜 閏求, 奥平 敦彦, 黒田 豊和
2001 年 17 巻 p.
493-498
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
A fatal swimming accident was occurred in an artificial beach in Tokyo Bay in July 30, 2000, where two elementary school children were killed due to relatively high waves in the bay. Field investigations including measurements of sea topography and numerical calculations to elucidate wave actions on the children on the beach were carried out. Large change in the water level due to a spring tide with a typical multiple bar-trough sea bottom topography is one of the reason of the accident.
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清野 聡子, 花田 一之, 宇多 高明, 角本 孝夫, 五味 久昭, 石川 仁憲
2001 年 17 巻 p.
499-504
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Public agreement in the planning of future coastal works was made through public hearings at the Kinoppu coast in Aomori Prefecture. Concrete measures against wave overtopping and improvement of coastal utilization were told local people, and a compromise was attained over the objective opinions through dense discussions. The process was described clearly. After the formation of the compromise, coastal works were conducted and a part of works has been finished until the end of fiscal year of 2000.
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片山 正敏
2001 年 17 巻 p.
505-510
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In planning and designing a marina for a public marine recreation to be involved in waterfront development, it is very important to grasp the significance of the waterfront for the urban residents and reflect it into the environmental consideration by clarifying the prosses of variation in their behavior and perception as visitors to the waterfront.
From the above viewpoint, questionnaire surveys were conducted and analyzed to investigate the utilization status and the visitors' perception at the marinas in Northern Kyushu.
In this paper, the outlines of the questionnaire survey at the seven marinas in Northern Kyushu are described, followed by the detailed results of the questionnaire survey and its multivariate analysis
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宇多 高明, 木戸 浩彦, 星上 幸良, 芹沢 真澄, 三波 俊郎, 古池 鋼
2001 年 17 巻 p.
511-516
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Factors of rapid change from natural sandy beach to artificial coastline covered by concrete armor units were investigated at the Setohama Beach in Sotobo area in Chiba Prefecture. The Setohama Beach was famous for oceanic recreation in the past, and along the coastline a national road runs. With the shoreline recession, wave overtopping became severe, and land reclamation over the sandy beach was carried out as well as the construction of gently sloping revetment in front as the measure at the sacrifice of natural sandy beach. A part of local people welcomed land reclamation because of widening of parking lot and the others claimed loss of nature. This process of change was investigated by field observation and comparison of past aerial photographs.
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千葉県白渚海岸の例
清野 聡子, 宇多 高明, 芹沢 真澄, 渡邉 義雄, 吉田 和幸, 星上 幸良
2001 年 17 巻 p.
517-522
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Public involvement method was introduced to solve the issue on coastal construction work at the Shirasuka coast in Chiba Prefecture. On this coast, gently sloping revetment had been built as the renewal work of the old seawall before the construction of the artificial reefs, causing heavy wave overtopping during typhoon. Fishermen and surfers objected to the construction of the artificial reefs because of killing good fishing ground and surf point. Public hearings were carried out to reach compromise. After the dense discussion, public agreement was made on future coastal works.
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清野 聡子, 宇多 高明, 山崎 一真, 安部 和典, 大谷 保, 大塚 浩二
2001 年 17 巻 p.
523-528
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In the planning of the improvement works of the fishing port to enhance its utilization level, it is usual to reclaim the surrounding area of the port. However, in case where the rich fishing ground is located in the vicinity of the port, the enhancement of utilization as well as upgrading of the port function and conservation of the marine environment become in conflict. Harmony of these conflicting conditions is becoming a serious problem in the development of the fishing port and its ambient area. This study aims at the creation of work scheme to reach consensus between local people for the improvement plan in harmony with environmental conservation in the surrounding sea area, taking Koshigoe fishing port in Kamakura City, Kanagawa Prefecture as the example.
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宇多 高明, 小菅 晋, 林 義之, 神田 康嗣, 渡邉 貴裕
2001 年 17 巻 p.
529-534
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Beach nourishment was carried out at Ukishima area in Lake Kasumigaura in order to recover sandy beaches. Artificial beach slope was set to be steep as much as 1/2. After the nourishment, longshore and offshore sand movement occurred due to the wind wave action. Beach profile changes were measured and sea bottom sampling were conducted. Measured beach changes were compared with the results of the numerical simulation by using the contour line change model. Both results agreed well.
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和田 清, 水谷 法美, 村上 宗隆
2001 年 17 巻 p.
535-540
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
This paper is intended to estimate seasonal beach process and wave deformations at the Ida coast in the Shichiri-Mihama coast in Mie Prefecture. Field investigation by using an aerial photography technique is conducted along the Shichiri-Mihama coast from the Kumano river mouth to the Onigajo cape. It is clear that almost regions occurred beach erosion, especially Udono port region located on the left bank of the Kumano river, as the coastal line faced to sea, the beach protection works were struck by strong storms. Based on bottom sounding survey, maximum shoreline retreat was about one hundred meter for five years immediately after extend construction of breakwater around Udonoh arbor.It is necessary to predict wave deformation for erosion control around coastal protection facilities. It is presented a time-depend mild slope equation for estimating wave deformation. Some simple calculations were conducted for modeling artificial reefs at the severe beach erosion area where located northern Udono port. The numerical model has well explanations for generation of partial standing waves, drop of mean sea level behind artificial reefs.
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西蔦 照毅, 狩野 俊男, 宇多 高明, 中辻 崇浩
2001 年 17 巻 p.
541-546
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Field investigation of lakeshore change induced by overflow on the groins was carried out at the Minamihama Beach in Lake Biwa. In this lake, the water level rises and rough waves are generated in winter. During this season, overflow often occurs on the groins, which were installed to stabilize the shoreline, and longshore sand transport occurs at the shoreward end of the groins, inducing beach erosion of the updrift beach of the groin. This situation was investigated by the field measurement.
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申 承鏑, 山口 洋, 入江 功
2001 年 17 巻 p.
547-552
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Recently, it is frequent that securing a vast space on the land region in turning out to be difficult and obliged to seek it in the sea area, and because of this, the coastal region has been faced to more wide-ranging beach erosion problems. In planning offshore structures such as artificial islands, it is necessary to forecast the influence of the structurec onstructiono n the beacha nd adjacentc oast.
In the present study, the sediment movement pattern behind offshore structure was studied through a series of three dimensionaml ovableb ed experimentsin an aim to developt he numericalm odel which forecastsm orphological change includingb each erosion. From the experimentalr esults, it has been understoodt hat the sedimentm ovement patterns near the surf zone and offshore zone are clearly separated and this was adopted in the model. The numerical model of morphologicacl hangeo f the coastt hus developedh as been foundt o reproducep hysicalmodels atisfactory
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宇多 高明, 花田 一之, 石川 仁憲, 清野 聡子, 太田 慶正, 角本 孝夫
2001 年 17 巻 p.
553-558
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Shoreline changes at the embayed coastline between Ohata fishing port and Shiriyazaki Point in Shimokita Peninsula were investigated by field observation and reading of aerial photographs. In this area, swells are incident from NE mainly in summer, whereas NW wind blows in winter causing rough wind waves. Since the shape of the coastline is semicircular and eastern half of the coastline is well protected by the peninsula itself against summer swells, predominant direction of littotal drift is eastward. Large shoreline recession with the formation of sea cliff was observed on the east side of harbor and detached breakwaters.
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熊田 貴之, 小林 昭男, 三波 俊郎, 宇多 高明, 芹沢 真澄, 古池 鋼
2001 年 17 巻 p.
559-564
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Beach changes at the Kemigawa artificial Beach in Tokyo Bay were investigated based on field surveys. Beach nourishment was conducted and the shoreline paralell to the seawall was formed.In order to enhance stability of nourished sand, curved groins were built at the south and north ends after the nourishment, forming wave calm zones in their lee sides. Large scale shoreline changes were triggered due to the construction. Beach changes were measured, and the changes in the beach profiles and the shoreline were studied. Comparison between the measured shoreline and that predicted by Hsu's model was made.
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宇多 高明, 古池 鋼, 芹沢 真澄, 三波 俊郎, 清野 聡子, 渡辺 宗介
2001 年 17 巻 p.
565-570
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Beach and dune changes on the Katano and Shioya coasts in Ishikawa Prefecture were investigated by comparison of aerial photographs and field observation. In this area, sand dune develops along the shoreline and main sediment source is the Daishoji River flowing into the central part of the coastline. The shoreline change shows recession on the west side of the river mouth, whereas the shoreline advances on the east side. The mechanism of shoreline changes was explained by the reasons that the eastward energy flux is bigger than the westward flux on this coast, and the intermittent sediment transport was induced by the eastward transport as an oneway transport by the weir effect of the river mouth jetties.
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宇多 高明, 弘田 英人, 三波 俊郎
2001 年 17 巻 p.
571-575
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
Causes of beach erosion on the southern Ishikawa coast facing the Sea of Japan was investigated based on the history of local area. In this area, the shoreline has been retreating, and in the previous studies the cause was said to be due to the offshore sand movement. However, in this area sand mining has been extensively carried out at and around the shoreline as well as dredging at two river mouths, where river mouth closure was severe. Thus, artificial causes cannot be ignored as the causes of beach erosion.
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奥村 慎也, 佐藤 幸雄, 榎本 浩之
2001 年 17 巻 p.
577-582
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
In the polar ocean, the existence value, such as a production activity and activity of a physical distribution, has increased very much. It is related with sea ice which exists in such ocean. As a previous study about sea ice and mutual interference of wave motion, there are studies about ice plate. Appearing by a growth process of sea ice, in grease ice that is thin slurry of frazil ice at the ocean surface, there are many fundamental studies. The present paper, we firstly ran two laboratory studies about sea ice and mutual interface of wave motion which use two models ice. One experiment is wave decay and the other one is wave propagation at thin grease ice layer in finite depth. Secondary, we introduce physical stress, a boundary layer thought about into viscous two-layer model, lead a dispersion relation and examine comparison with an experiment. As a result, we obtained results that differ from previous study which dispersion relation.
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佐伯 浩, 川合 邦宏, 渡部 靖憲, 橘 治国, 今泉 章, 松尾 優子
2001 年 17 巻 p.
583-587
発行日: 2001年
公開日: 2011/06/27
ジャーナル
フリー
This is a report on the results of experiments aimed to clarfy the optimal section form of sink-and-float type ice boom (SFIB) which may prevent SFIB from becoming buried in send when it sinks and on the results of in site tests at Saroma Lagoon which is located on the Okhotusk sea coast of Hokkaido.
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