担当区分：筆頭著者  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：日本海洋学会  

九州西岸の有明海奥部海域において,近年夏季に発生する底層水の貧酸素化現象および頻発する赤潮の発生メカニズムを解明するため,2001年8月より2002年2月まで毎月1回,水質調査を行った。本調査期間中,8月上旬に底層で貧酸素水塊が,11月に珪藻赤潮がいずれも大雨の後に発生し,その発生過程を次のようにまとめた。1.夏季の貧酸素水塊 梅雨期の大雨→河川からの大量の淡水の流入→表層の塩分低下による成層構造の発達・夏季の気温上昇に伴う水温の成層構造の発達→底層水の貧酸素化 2.秋季の珪藻赤潮 秋季の大雨→河川からの大量の淡水の流入・大量の栄養塩の供給→低塩分・高栄養塩濃度の表層水の形成→赤潮の発生 1998年以降,秋季の赤潮は大規模化する傾向が認められる。有明海奥部海域では,塩分や水温による成層構造が発達した時に,海水交換に大きな変化が生じ,海水が滞留しがちになることで赤潮が発生している可能性が指摘される。In the innermost areas of Ariake Bay, on the west coast of Kyushu, hypoxia of the bottom has occurred during the summer since 1997 and red tides have occurred more frequently since the 1990s. We monitored water conditions in Ariake Bay monthly from August 2001 to February 2002 (I.e. vertical profiles of salinity, temperature, DO and chlorophyll a, and nutrient concentrations in the surface layers). The results of our studies indicate that both the hypoxic water in the summer and the large scale of red tides of diatoms in the autumn, occurred after heavy rain fall. The processes appear to be as follows: 1. Occurrence of hypoxia of the bottom water during the summer: Heavy rain during the rainy season results in an inflow of a large amount of fresh water from rivers causing stratification of the water column to develop. Lower salinity and higher temperature at the surface from the heavy rain and strong solar radiation during the summer then causes hypoxia due to a lack of mixing. 2. Large scale diatom blooms in the autumn: Heavy autumn rains cause the inflow of a large amounts of fresh water from the rivers which contain a high concentration of nutrients. The stabilization of the surface layer of water with low salinity and high nutrient concentration results in the diatom blooms. We further suspect that the water in the innermost areas of Ariake Bay has become more stagnant than before due to the construction of a dike in Isahava Bay, which is located in the inner bay of Ariake Bay. The restriction of water exchange in the innermost areas of Ariake Bay may have caused these two phenomena.

担当区分：筆頭著者   出版者・発行元：公益社団法人 土木学会  

Komatsu et al.(1997) have recently proposed a new water-purification method in a semi-enclosed coastal area. By means of this method, to activate the tidal exchange between the inner and outer sea area, installing many bottom structures &ldquo;<I>Bottom Roughness</I>&rdquo; controls a pattern of tidal residual current, which have an unsymmetrical 3-dimensional shape. In order to confirm the effect of the present method in an actual coastal area we started prototype test since May 2000 in New Nagasaki Fishery Port, Nagasaki, Japan. In this prototype test, 60 units of bottom roughness, whose height and width were 4m respectively, were installed on the bottom near two mouths of the port in May 2001. In this paper, some processes to apply this water-purification method to New Nagasaki Fishery Port were reported.

DOI： 10.2208/prooe.19.297

出版者・発行元：公益社団法人 土木学会  

2001年10月16日に有明海全域において, ADCP12台とSTD8台を用いた流動構造と成層の一斉観測が実施された. 観測日として混合期の日潮不等の小さい大潮時が選ばれ, 一潮汐間に渡って観測が行われた. 得られた主要な結果,(1) 島原半島に沿った狭い領域に強い表層流が存在し, 塩淡成層が形成されており, この流れが物質輸送に大きな役割を果たしている,(2) 諫早湾湾口では両端部から流出し, 中央部から流入する残差流パターンが形成される,(3) 有明町と長洲を結ぶ有明海の狭窄部を挾んで混合形態が変化しており, この断面の海水交換特性が有明海の水質構造を規定してる, などである.

DOI： 10.2208/proce1989.50.936

出版者・発行元：公益社団法人 土木学会  

新長崎漁港では, 近隣の水産加工工場からの排水, 水産物の蓄養筏増設に起因する底質汚濁および防波堤による港内外の海水交換の阻害などによって, 将来の水質悪化が懸念されている. そのような中, 小松ら (1997) が提案している流況制御ブロックを用いた海水交換促進技術に関する実証実験が2001年5月に実施され, 60基の流況制御ブロックが沈設された. 本論文では, ブロック沈設前の2000年5月から沈設後の2002年12月にかけて実施された流動構造の現地観測について報告する. その結果, ブロック設置前後の残差流の鉛直断面分布, 潮流楕円および残差環流等の変化から, 流況制御ブロックは海水交換促進効果を有することが確認された.

DOI： 10.2208/proce1989.50.1201

出版者・発行元：公益社団法人 土木学会  

新長崎漁港では, 近隣の水産加工工場からの排水, 水産物の蓄養筏増設に起因する底質汚濁および防波堤による港内外の海水交換の阻害などによって, 将来の水質悪化が懸念されている.そのような中, 小松ら (1997) が提案している流況制御ブロックを用いた海水交換促進技術に関する実証実験が2001年5月に実施され, 60基の流況制御ブロックが沈設された. 本論文では, ブロック沈設前の2000年5月から沈設後の2002年1月にかけて実施された水質動態の現地観測について報告する. その結果, 蓄養筏が多数設置されている観測点 (10) ではCODの値が減少するとともに, ブロック沈設前に観測された貧酸素水塊が発生せず, 水質改善の傾向が確認された.

DOI： 10.2208/proce1989.49.1266

出版者・発行元：日本水産工学会  

DOI： 10.18903/pamjsfe.2002.0_51

出版者・発行元：公益社団法人 土木学会  

Directional characteristics of wave-induced residual current and control of littoral sand drift depending on wave direction and an angle of plural asymmetrical bottom roughness (we call the asymmetrical bottom roughness BaNK block) were experimentally investigated. Firstly, the distribution of residual velocity on the fixed bed with the bended BaNK blocks was measured in a 3-dimensional wave field. Secondly, the deformation of movable bed due to the effect of blocks was measured in other fields. As a result, direction of wave-induced residual current could be arbitrarily changed by setting blocks with an angle. Furthermore, it was dmonstrated that the BaNK blocks are able to control littoral sand drift in a 3-dimensional wave field with movable bed.

DOI： 10.2208/prohe.46.457

担当区分：筆頭著者   出版者・発行元：公益社団法人 土木学会  

本研究では小規模海域における現地観測の重要性を指摘し, 長崎県新長崎漁港での現地観測を実施した. これまでの研究成果から, 同海域の夏季の残差流構造は主に港内外の密度差によって説明できるということが明らかにされているため, 本論文では特に港内外の密度分布に違いが生じる要因に着目して検討を行った. その結果, 新長崎漁港の成層構造は風の影響を強く受けており, 流動構造と密度場が互いに影響を及ぼしながら非定常な変化を示していることが分かった. また, 数日周期の一方向に卓越する南風によって引き起こされる残差流構造が夏季の海水交換に大きな役割を果していることが示唆された.

DOI： 10.2208/proce1989.49.1091

出版者・発行元：公益社団法人 土木学会  

DOI： 10.2208/proce1989.48.406

担当区分：筆頭著者   出版者・発行元：公益社団法人 土木学会  

DOI： 10.2208/proce1989.48.1041

出版者・発行元：公益社団法人 土木学会  

The problem of beach erosion in our country grows more and more serious, so we must countermeasure against this problem without delay. Then we develop a effective method (we call the blocks used in this method BaNK block) to control sediment transport to cope with this serious problem. In this paper, we examine the fundamental properties of this method by laboratory experiments and field works in Nogita Coast. Firstly, we investigated the condition of flow occurrd when BaNK blocks were set in a wave progressing field by laboratory experiments. We confirmed that this method could make a flow at bottom layer and made a proper layout of BaNKblocks dear. Secondly, we set two kinds of blocks in Nogita Coast and observed a sediment transport around these blocks. By this field works we confirmed that sediment was transported by BaNKblocks to the direction we expected. From these results, we confirmed the possibility of beach nourishment by using BaNK blocks.

DOI： 10.2208/prohe.45.1087

出版者・発行元：公益社団法人 土木学会  

Nowadays water pollution caused by eutrophication in a semi-enclosed bay has been a serious problem. In order to solve this problem, a method has been proposed to activate the water exchange between an inner bay and its outer sea area by using Bottom Roughness with directional resistance properties. In this paper, a possibility for practical use of this method was examined from many angles. First, the basic effect of Bottom Roughness on substance transport was examined by a laboratory experiment Next, 2-dimensional numerical simulations were carried out to estimate the validity of this method in the Nagoya Port that has a complicated topography. Lastly, it was it-ported that four kinds of Bottom Roughness were sunk to investigate their influence on the scour of seabed and the water environment. From these results, it becomes clear that this method is efficient to improve the water quality in real sea areas.

DOI： 10.2208/prohe.44.957

出版者・発行元：公益社団法人 土木学会  

DOI： 10.2208/proce1989.47.476

出版者・発行元：公益社団法人 土木学会  

Nowadays, water pollutions in many semi-enclosed bays have been a very serious social problem. In order to solve this problem, we have proposed the method to activate the water exchange between a bay and its outer sea area by using bottom roughness. In thisstudy, we developed two types of bottom roughness and examined their resistance properties experimentally. At first, the bottom roughness which could create the tide-induced residual current normal to the main tidal flow was improved. Then, it was made clear that the bottom roughness with the shape of a quarter sphere had the property to produce directly the tide-induced residual current not only in the parallel direction but also in the arbitrary direction to the main tidal flow. Finally, it was confirmed from the results of the numerical experiment that the combination of these bottom roughness could efficiently make a stronger residual circulation.

DOI： 10.2208/prohe.43.833

出版者・発行元：公益社団法人 土木学会  

Nowadays in most of semi-enclosed bays water qualities have been deteriorated. Wehave proposed the method to create and control the tidal residual current by bottom roughnessfor activating the tidal exchange. In this paper we introduced the new type of bottomroughness with a function to bend the flow direction and experimentally developed the mosteffective shape. Next we tried to examine the effect of <I>the bending roughness</I> by numericasimulation in the model bay. As a result, it is made clear that quarters of the cylinder arrangedin two rows can get the large drag force in the normal direction of the flow and thatthe tidal exchange is promoted by the combination of the bottom roughness and the bending roughness.

DOI： 10.2208/prohe.42.577

出版者・発行元：公益社団法人 土木学会  

In a slender enclosed bay, which has a very long longitudinal length compared with a transverse width, the tidal residual current is composed of a series of circulations, that is so-called multi-cell structure. In order to examine the effect of multi-cell of tidal residual current on mass transfer and on the tidal exchange, numerical simulations of tidal current and contaminant transport were carried out in a slender model enclosed bay. As a result of this research, it turned out that the ratio of the scale of the tidal residual circulation (cell) to the dispersion scale is a very important factor for determination of the suitable pattern of the tidal residual current to activate the tidal exchange.

DOI： 10.2208/prohe.42.589

出版者・発行元：公益社団法人 土木学会  

These days, pollution in a stagnant water area of a semi-enclosed bay is recognized as one of serious water environmental problems. In order to activate the tidal exchange, we proposed a new method to create and control a tidal residual current by using artificial bottom roughness with directional resistance property. On the basis of this idea it was attempted to determine the most effective shape of roughness experimentally. As a result of this research, it was made clear that the half cylinder type, half sphere type and other two types could get large differences of drag coefficient between two flow directions.

DOI： 10.2208/prohe.41.705

出版者・発行元：公益社団法人 土木学会  

Water pollution in a semi-enclosed sea area such as a bay or a fishing port due to stagnancy of water has been a serious problem on water environment. We proposed a new method to activate the tidal exchange between an inner and an outer sea area by creation and control of a tidal residual current. In this new method, the tidal residual current is produced and controlled by artificial structures, which change properties of resistance according to a direction of flow, set on the bottom. In this study, several tidal current and particle movement simulations with various arrangements of artificial bottom roughness in a semi-enclosed model bay were carried out. As a result of many kinds of numerical experiments, it becomes clear that it is possible to generate the tidal residual current and to activate the tidal exchange by only operation of bottom roughness.

DOI： 10.2208/prohe.41.323