河道内砂礫州の樹林化し易さを評価する簡易指標として，破断・倒伏・転倒評価指標 (BOI)と流失評価指標(WOI)を組み合わせて，未破壊・未流失，破壊・未流失，未破壊・流失，破壊・流失の 4領域（それぞれ，Region A, B, C, D）を定義した．荒川・多摩川にて両指標の有効性を検証後，複数砂礫州の7地点において洪水確率毎に領域分類を行った．その結果，洪水規模の増大により Region AからD（パターン I）， Region AからB（パターン II）への変化という典型的なパターンが存在した．パターン IIでは樹木破壊は生じるが流失は生じないため，再生能力の高い樹木が侵入した場合は，安定樹林帯となる可能性が高い．パターンIIに対する河道対策としては，パターンIになるような対策を講じる必要がある．
{"title":"METHOD FOR EVALUATING THE DYNAMICS OF FOREST IN RIVERS CONSIDERING TWO INDICES REPRESENTING THE BREAKING AND WASH-OUT CONDITIONS OF TREES ON GRAVEL-BED BARS","authors":"N. Tanaka, J. Yagisawa, S. Fukuoka","doi":"10.2208/JSCEJB.66.359","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.359","url":null,"abstract":"河道内砂礫州の樹林化し易さを評価する簡易指標として，破断・倒伏・転倒評価指標 (BOI)と流失評価指標(WOI)を組み合わせて，未破壊・未流失，破壊・未流失，未破壊・流失，破壊・流失の 4領域（それぞれ，Region A, B, C, D）を定義した．荒川・多摩川にて両指標の有効性を検証後，複数砂礫州の7地点において洪水確率毎に領域分類を行った．その結果，洪水規模の増大により Region AからD（パターン I）， Region AからB（パターン II）への変化という典型的なパターンが存在した．パターン IIでは樹木破壊は生じるが流失は生じないため，再生能力の高い樹木が侵入した場合は，安定樹林帯となる可能性が高い．パターンIIに対する河道対策としては，パターンIになるような対策を講じる必要がある．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"14 1","pages":"359-370"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78994003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SEMI-IMPLICIT ALGORITHM OF PARTICLE METHOD ACCELERATED BY GPU","authors":"H. Gotoh, Chiemi Hori, H. Ikari, Abbas Khayyer","doi":"10.2208/JSCEJB.66.217","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.217","url":null,"abstract":"粒子法は複雑な自由表面の変化の追跡に適していることから，水工学分野でも有用性が示され，海岸工学においては数値波動水槽への応用も進められている．しかし計算負荷が高いため，ハードウェアへの相応の投資が必要となり，これが一般利用の障害となっている．ところで，画像処理目的に開発されてきたGPUを，一般的な学術演算の高速化に利用する取り組みが最近活発となっている．本研究では，MPS法を高速化する手段のひとつとして，CUDAによるGPU併用コードを開発した．高速化を達成するための留意点を整理し，MPS法計算コード固有の特性に適合するように移植を行った．メモリ配置の工夫に加えて，計算のコアとなる近傍粒子探索や圧力のPoisson方程式の収束計算については，GPU計算を効率化するため，特に綿密に検討した．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"55 1","pages":"217-222"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74584772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"MEASUREMENT OF INTERFACE BETWEEN FRESH WATER AND SALT WATER USING ENERGY ABSORPTION CHARACTERISTICS IN MICROWAVE","authors":"Yuji Ito, Hideki Miyamoto, M. Koriyama, J. Chikushi, M. Seguchi","doi":"10.2208/JSCEJB.66.189","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.189","url":null,"abstract":"淡塩水境界面の位置計測に対する時間領域反射法（TDR）の有効性を評価するために，48cm長プローブを用いて，その先端から境界面までの距離hiの計測の可否と精度を調べた．hiを評価するために，本法では，プローブに与えたマイクロ波ステップパルスのTDR波形が，塩水によるエネルギー吸収によって急変する特徴を利用した．水質変化を想定し，淡水の電気伝導度σfwが異なる条件でhiを評価した結果，淡水中を伝播するパルスのエネルギー損失が大きい場合，すなわちσfwが高く，淡水層が厚い場合にhi計測が困難になった．しかし，高σfw条件でも，淡水層が薄くなりエネルギー損失が抑制されると，hiは計測可能となり，測定誤差は概ね1cm未満となった．また，たとえ境界面が変動しても，静的な水理条件では同等の精度でhiを評価できることを確認した．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"29 8","pages":"189-195"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91480761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"STUDY ON APPLICABILITY OF LANDUSE REGULATION STRATEGIES BASED ON FLOOD RISK ASSESSMENT","authors":"M. Teramoto, Y. Ichikawa, Y. Tachikawa, M. Shiiba","doi":"10.2208/JSCEJB.66.130","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.130","url":null,"abstract":"","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"24 1","pages":"130-144"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78069057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"NUMERICAL ANALYSIS OF ALLUVIAL FAN FORMATION ON A PERMEABLE PLAIN","authors":"Motoki Ogasawara, M. Sekine","doi":"10.2208/JSCEJB.66.167","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.167","url":null,"abstract":"土砂を輸送してきた流れが透水性の高い平地上に流入すると，そこには扇状地にも似た堆積地形が形成される．本研究では，このような堆積地形の形成過程を数値的に再現することのできる解析モデルを構築することを目的とする．ここでは，地形の縦横断勾配の影響を合理的に考慮した掃流砂量の評価方法と，斜面崩落モデルとを組み込んだほか，表面流に加えて飽和・不飽和浸透流についても同時に解析することにした．この解析モデルの妥当性については，模型実験の結果とこれと同一条件下で行われた数値解析の結果とを比較することにより検討された．これにより，堆積地形の拡大が「流路の移動・消滅・再形成」のプロセスと密接に関わりながら進行することが確認されたほか，本解析によりこの過程が概ね合理的に再現できることも示された．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"26 1","pages":"167-178"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72666938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"RIVER WATER LEVEL PREDICTION BY IMPROVEMENT OF NEAREST-NEIGHBOR METHOD","authors":"T. Hiraoka, M. Ikari, H. Yuki","doi":"10.2208/JSCEJB.66.99","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.99","url":null,"abstract":"本ノートでは，河川の水位を予測するためにこれまで用いられてきたNearest-Neighbor法を拡張して，より精度良く河川の水位を予測できる方法を提案する．まず本ノートの背景と目的を示し，次にNearestNeighbor法のアルゴリズムについて概説し，その後に提案法のアルゴリズムについて説明する．更に，実データを用いた実験によって得られる従来のNearest-Neighbor法と提案法の結果を比較することで，提案法の有効性を検証する．最後に，本ノートのまとめと今後の展望について示す．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"8 1","pages":"99-103"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85415726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study is to make clear a second closure turbulence model which can correctly and economically reproduce turbulence in stratified open channel flows. This study focuses on 2 representative second closure models, and assesses those performance. Firstly, the changes in the Prandtl-Kolmogorov constant and turbulent Schmidt number of those models are compared using analytical approach. Then, the accuracy is assessed using the experimental results in tidal estuarine flume. Finally, the model-constants which can reproduce the experimental results are made clear with reference to the findings obtained by DNS and LES analyses.
{"title":"PERFORMANCE OF SECOND CLOSURE TURBULENCE MODELS FOR STRATIFIED OPEN CHANNEL FLOW","authors":"T. Adachi","doi":"10.2208/JSCEJB.66.76","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.76","url":null,"abstract":"The purpose of this study is to make clear a second closure turbulence model which can correctly and economically reproduce turbulence in stratified open channel flows. This study focuses on 2 representative second closure models, and assesses those performance. Firstly, the changes in the Prandtl-Kolmogorov constant and turbulent Schmidt number of those models are compared using analytical approach. Then, the accuracy is assessed using the experimental results in tidal estuarine flume. Finally, the model-constants which can reproduce the experimental results are made clear with reference to the findings obtained by DNS and LES analyses.","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"2014 1","pages":"76-86"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87755879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sedimentation aspects have a major role during the design of new reservoir projects because life of the reservoir mainly depends upon sediment handling during reservoir operation. Therefore, proper sediment management strategies should be adopted to enhance the life span of reservoirs. Basha Reservoir is one of the mega water resources projects which are being planned to construct on the Indus river. Under this study, the efficiency of four sediment management strategies were evaluated by using the RESSASS model. The reservoir management strategies considered for sediment simulation of Basha reservoir include the normal operation, raising of MoL, draw-down the MoL (flushing) and controlling the sediment inflows. Under normal operation, the model predicted the life span of Basha reservoir around 55-60 years. But by raising of Mol 2.0m/year implemented after 35 years of operation may add 10-15 years more to the life-span of the reservoir. However, by adopting the flushing operation to draw-down the MoL at El.1010m initiated after 35 years of operation, it may also add about 15-20 years more. Moreover, the results obtained by considering 50% reduction in sediment inflow due to implementation of river basin management projects upstream of Basha within 30 years of reservoir operation, depicts that the life of the reservoir will be more than 100 years. It is therefore concluded that proper sediment mitigation measure can significantly enhance the life-span of planned reservoirs.
{"title":"EVALUATION OF SEDIMENT MANAGEMENT STRATEGIES ON RESERVOIR STORAGE DEPLETION RATE: A CASE STUDY","authors":"M. Ali, G. Sterk","doi":"10.2208/JSCEJB.66.207","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.207","url":null,"abstract":"Sedimentation aspects have a major role during the design of new reservoir projects because life of the reservoir mainly depends upon sediment handling during reservoir operation. Therefore, proper sediment management strategies should be adopted to enhance the life span of reservoirs. Basha Reservoir is one of the mega water resources projects which are being planned to construct on the Indus river. Under this study, the efficiency of four sediment management strategies were evaluated by using the RESSASS model. The reservoir management strategies considered for sediment simulation of Basha reservoir include the normal operation, raising of MoL, draw-down the MoL (flushing) and controlling the sediment inflows. Under normal operation, the model predicted the life span of Basha reservoir around 55-60 years. But by raising of Mol 2.0m/year implemented after 35 years of operation may add 10-15 years more to the life-span of the reservoir. However, by adopting the flushing operation to draw-down the MoL at El.1010m initiated after 35 years of operation, it may also add about 15-20 years more. Moreover, the results obtained by considering 50% reduction in sediment inflow due to implementation of river basin management projects upstream of Basha within 30 years of reservoir operation, depicts that the life of the reservoir will be more than 100 years. It is therefore concluded that proper sediment mitigation measure can significantly enhance the life-span of planned reservoirs.","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"3 1","pages":"207-216"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79993124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"WIND RESPONSE OF HYPOXIC WATER MASS IN ISAHAYA BAY","authors":"N. Matsunaga, Hongyuan Li","doi":"10.2208/JSCEJB.66.395","DOIUrl":"https://doi.org/10.2208/JSCEJB.66.395","url":null,"abstract":"九州農政局が提供している諫早湾の海上風データと水質データを用いて，諫早湾に形成される貧酸素水塊の風応答特性を調べた．諫早湾では夏季に南南西の風と北北東の風が卓越する．諫早湾口部や湾中央部の底層で形成された低酸素水塊は，南寄りの風によって湾奥部へ輸送されながら酸素を消費し，貧酸素水塊となる．吹送時間が長い場合や風速が大きい場合，貧酸素水塊は湾奥部で湧昇する．一方，北寄りの風は溶存酸素（DO）濃度の高い表層水を湾奥部に吹き寄せ，底層の水塊を湾口に向かって輸送する．従って，南寄りの風が連吹する場合，諫早湾奥部のDO濃度は低下し，北寄りの風が連吹する時，DO濃度は回復する．貧酸素水塊の岸沖方向の移動速度は，水表面に作用する風応力の大きさに依存するものの，数100m/hのオーダと見積られた．","PeriodicalId":11343,"journal":{"name":"Doboku Gakkai Ronbunshuu B","volume":"10 1","pages":"395-406"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82598818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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