業績情報

• バングラデシュ ハオール地域における高規格道路および河川堤防群が洪水氾濫に及ぼす影響　　　　　　　　　　　　　　　
  Sowmitra Das Shuvro; 八木澤順治
  土木学会論文集特集号（水工学）, 巻：13, 号：2, 開始ページ：24, 終了ページ：29, 2025年12月, ［査読有り］, ［責任著者］
  英語, 研究論文（学術雑誌）
• Experimental Study of Scouring and Deposition Characteristics of Riprap at Embankment Toe Due to Overflow　　　　　　　　　　　　　　　
  Abu Raihan Mohammad Al-Biruni; Md Masum Billah; Junji Yagisawa
  GEOTECHNICS, 巻：4, 号：3, 開始ページ：773, 終了ページ：785, 2024年09月
  In this study, the effects of the grain size and gradation of riprap, the overtopping flow depth, and the downstream slope of the embankment on the scouring and deposition characteristics at the downstream toe of the embankment were investigated. For the experiment, three different downstream slopes (1:2, 1:3, and 1:4), three different overflow depths (1, 2, and 3 cm), and three different sizes of riprap particles (d50 of 16.41 mm, 8.48 mm, and 3.39 mm, herein referred to as coarse gravel, medium gravel, and granule, respectively) were used in the laboratory. The experimental results demonstrated that the scour depth and deposition height increased with increasing energy head for each downstream slope condition. Among the three particle sizes, coarse gravel shows the lowest scour depth and the highest deposition height. For the 1:2 slope, the coarse gravel particle size was 62% and 75% less resistant to scouring than the medium gravel and granule particles, respectively. For the 1:3 slope case, this was 31% and 46%, and for the 1:4 slope case, this was 39% and 49% less than the medium gravel and granule size particles, respectively.
  MDPI, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/geotechnics4030040
  DOI ID：10.3390/geotechnics4030040, eISSN：2673-7094, Web of Science ID：WOS:001323875200001
• Headcut Migration in Earthen Embankment Induced by Varying Sub-surface and Seepage State under Overflow　　　　　　　　　　　　　　　
  Md Masum Billah; Junji Yagisawa
  GEOTECHNICAL AND GEOLOGICAL ENGINEERING, 巻：41, 号：8, 開始ページ：4659, 終了ページ：4676, 2023年11月
  In this study, the effects of an erosion resistant (ER) layer underneath the embankment and the seepage state prior to overflow were investigated. In the model experiment, tracing the headcut location using an Radio Frequency Identification (RFID) system without stopping the overflow demonstrated that the existence of an ER layer has a significant effect on the headcut migration rate, with a decrease in depth to the ER layer from 4.5 to 1.5 cm, the migration speed increased considerably by 1.20-1.86 times that of the case without an ER layer. When prolonged immersion prior to overflow was allowed, with the increase in the intensity of seepage, the headcut migration rate also increased, and as time elapsed, the effect of ER layer became subservient, though the degree of dominance of the seepage throughout the overflow period is controlled by the ER layer position. Thus, seepage state during prolonged immersion and ER layer underneath embankment toe needs special design consideration.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10706-023-02538-x
  DOI ID：10.1007/s10706-023-02538-x, ISSN：0960-3182, eISSN：1573-1529, Web of Science ID：WOS:001022143100002
• アユの採餌環境を対象とした河床環境数値予測モジュールの開発　　　　　　　　　　　　　　　
  溝口 裕太; 宇佐美 将平; 八木澤 順治; 小野田 幸生; 田代 喬; 宮川 幸雄; 中村 圭吾
  土木学会論文集Ｂ１（水工学）, 巻：77, 号：2, 開始ページ：I_559, 終了ページ：I_564, 2021年
  アユの採餌環境を対象に，その空間分布の支配要因である砂被度の記述を目的とした，河床環境数値予測モジュールの開発を試みた．二峰性を有する対象地の河床材料の特徴にしたがい，河床礫の表面や空隙に堆積する砂（間隙材料）の浮遊状態での移動を，数値解析におけるモデル化の対象とした．UAV空撮写真から求めた砂被度を用いて，当該モジュールの再現性を検証した結果，間隙材料の空間的な特徴を大局的に記述できるが，間隙材料の堆積を過大もしくは，過少に見積もる傾向を確認した．また，間隙材料の堆積は，流量逓減期に水際部から生じ，その終盤には，堆積が流心付近に及ぶ場合があることを数値解析による砂被度の時系列変化から明らかにした．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.77.2_i_559
  DOI ID：10.2208/jscejhe.77.2_i_559, eISSN：2185-467X, CiNii Articles ID：130008160137
• 難侵食層が法尻周辺の洗堀に及ぼす影響　　　　　　　　　　　　　　　
  西川 咲良; 八木澤 順治
  土木学会論文集Ｂ１（水工学）, 巻：76, 号：2, 開始ページ：I_1165, 終了ページ：I_1170, 2020年
  2019年台風 19号時に都幾川の破堤地点では，粘土層が露出し下方侵食が妨げられていたことが確認された．こうした層化した難侵食層の露出は，上流方向への侵食を助長し破堤までの時間を早める可能性がある．そこで，本研究では，難侵食層が堤体侵食に与える影響を水理模型実験により明らかにした．
  
  実験の結果，難侵食層の鉛直位置が1/4ZWO(ZWOは難侵食層が無い場合の裏法尻地点の残留土砂高)と2/4ZWOのケースでは，無次元越流水深h1/H(h1:越流水深，H:堤防高)が0.175の時にZi/ZWOが極小値をとる一方で，3/4ZWOでは単調減少となることを明らかにした．このことは，難侵食層の鉛直位置によっては，法尻付近の洗掘規模とその後の発達に対して危険となる越流条件があることを示唆している．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.76.2_i_1165
  DOI ID：10.2208/jscejhe.76.2_i_1165, eISSN：2185-467X, CiNii Articles ID：130008122547
• Tsunami mitigation by combination of coastal vegetation and a backward-facing step　　　　　　　　　　　　　　　
  Ghufran Ahmed Pasha; Norio Tanaka; Junji Yagisawa; Fuadi Noor Achmad
  Coastal Engineering Journal, 巻：60, 号：1, 開始ページ：104, 終了ページ：125, 2018年
  Since the 2011 Great East Japan tsunami, many improvements have been made in both hard and soft solutions for tsunami mitigation. After the 2011 Great East Japan tsunami, a post-tsunami survey was conducted along the coast in Miyagi Prefecture, which was one of the most tsunami-affected sites because rapid acceleration of the tsunami currents broke and washed away the trees, resulting in extensive damage to inland houses. In contrast, some of the houses located inland and away from vegetation with a dropping step survived. This shows a possibility that a step combined with the vegetation offers greater tsunami energy reduction by providing additional resistance. Laboratory experiments were conducted to investigate the energy reduction through a compound defense system (vegetation and a backward-facing step). Vegetation with a step (VS) showed greater energy reduction compared to that of only vegetation without a step (OV) due to additional loss by collision with the bed surface. However, the relative energy reduction in OV remained almost constant with the increase in the initial Froude number (F0, where the Froude number is obtained from a model without vegetation in a flume), whereas the relative energy reduction in VS showed a decreasing trend with increasing F0 because the energy reduction due to collision decreases with increase in water depth or F0.
  Taylor and Francis Ltd., 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/21664250.2018.1437014
  DOI ID：10.1080/21664250.2018.1437014, ISSN：1793-6292, eISSN：1793-6292, SCOPUS ID：85058053571, Web of Science ID：WOS:000432689400008
• Effect of Submergence Condition and Overtopping Depth on Gully Scour Dimensions: Observations from the 2011 Great East Japan Tsunami　　　　　　　　　　　　　　　
  Sazia Afreen; Junji Yagisawa; Norio Tanaka
  JOURNAL OF EARTHQUAKE AND TSUNAMI, 巻：11, 号：2, 2017年06月, ［査読有り］
  When a tsunami reaches a shore, it propagates along river channels with tremendous energy and overtops river levees. It causes severe damage to the levee structures through scouring along levee slope. In the present study, gully scours created along the levee slopes of two rivers (Omotogawa and Sakarigawa Rivers) in Iwate Prefecture and three rivers (Nanakitagawa, New Kitakamigawa, and Abukumagawa Rivers) in Miyagi Prefecture were investigated after the 2011 Great East Japan tsunami. The energy head during levee overtopping for each location was calculated from post-tsunami surveys. The relationship between the energy head and gully scour dimensions (length, width, and depth) was analyzed. The analyses clarified that gully scour dimensions were greatly dominated by two important phenomena: (i) overflow type (free overflow or submerged overflow), and (ii) soil texture at the scoured region. The present study results can be utilized to obtain the overtopping flow height for post-tsunami analysis.
  WORLD SCIENTIFIC PUBL CO PTE LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1142/S1793431117500014
  DOI ID：10.1142/S1793431117500014, ISSN：1793-4311, eISSN：1793-7116, Web of Science ID：WOS:000401142700004
• 埼玉県川島町を対象とした洪水氾濫解析に基づく避難支援バスの最適運行経路の検討—NUMERICAL STUDY ON OPTIMUM ROUTE OF EVACUATION ASSISTANCE BUS BASED ON FLOOD INUNDATION MODEL FOR KAWAJIMA TOWN　　　　　　　　　　　　　　　
  八木澤 順治; 大窪 和明; 田中 規夫; 赤崎 佑太
  水工学論文集 Annual journal of Hydraulic Engineering, JSCE / 土木学会水工学委員会 編, 巻：61, 号：4, 開始ページ：Ⅰ_313, 終了ページ：318, 2017年
  本研究では洪水流と氾濫流を一体的に解析する数値解析モデルを開発し，埼玉県川島町に適用した．町内の氾濫特性が大きく異なる２つ(市野川氾濫ケース(Case A)と都幾川氾濫ケース(Case B))の出水に適用し，町内に設定した一次避難所への氾濫流の到達時間を把握した．
  氾濫特性をもとにコミュニティバスを活用した最適避難経路を把握した．その結果，Case Aでは，氾濫開始前に町内の西部に位置する一次避難所を巡回し，氾濫開始後に東部の一次避難所を巡回する経路が総避難時間を最小化した．一方，Case Bでは，氾濫開始前に北部に位置する一次避難所を，氾濫開始後に南部を巡回する経路が総避難時間を最小化した．この結果は，越流地点やその後の氾濫形態の相違に応じて，どの地域を優先的・重点的に運行すべきかを事前に判断できる可能性を示唆している．
  東京 : 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.73.i_313
  DOI ID：10.2208/jscejhe.73.i_313, ISSN：1880-8751, eISSN：2185-467X, CiNii Articles ID：40021162462, CiNii Books ID：AN10426673
• 現地観測および水路模型実験による震災後の浪板海岸の漂砂動態評価　　　　　　　　　　　　　　　
  八木澤 順治; 武村 武; 小野 翔太郎; 板橋 直樹; 篠嶋 賢一; 鈴木 純平; 田中 規夫
  土木学会論文集B3（海洋開発）, 巻：72, 号：2, 開始ページ：I_187, 終了ページ：I_192, 2016年
  本研究では岩手県浪板海岸において，東日本大震災後の年間を通じた漂砂動態の把握を目的としたカラーサンドの追跡調査と，震災時の地震による地盤沈下の影響が漂砂動態に及ぼす影響を明らかにすることを目的とした水理模型実験を実施した．その結果，カラーサンドの追跡調査から，冬季・夏季ともに，投入した砂(d₅₀=0.6-1.0mm)の大部分が短期間で移動限界水深地点よりも沖側に輸送される可能性は少なく，養浜で同程度の材料を用いた場合，その一部が砂浜の再形成に寄与する可能性があることがわかった．また，水理模型実験より，震災前後の地盤高によらず汀線付近では冬季に砂が減少し，夏季に増加するという震災前と同様の漂砂動態の傾向を維持しており，養浜により地盤高が回復すれば砂浜が再生される可能性があることを明らかにした．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejoe.72.I_187
  DOI ID：10.2208/jscejoe.72.I_187, eISSN：2185-4688, CiNii Articles ID：130005263266
• 実測データベースに基づく河川堤防の越流決壊・破損条件の検討　　　　　　　　　　　　　　　
  服部 泰士; 二瓶 泰雄; 大槻 順朗; 八木澤 順治
  土木学会論文集Ｂ１（水工学）, 巻：71, 号：4, 開始ページ：I_1285, 終了ページ：I_1290, 2015年
  Levee breaches occurred at a lot of rivers mainly due to overflow of extreme flood. However it is not clear what hydraulic and material conditions can cause failures of conventional levees or not due to the lack of field data on levee failures. In the present study, we conducted field surveys for levee failures due to overflow erosion and made database of the levee failures. In the field surveys, we collected hydraulic conditions like overflow depth, failure conditions and size of levees. The results indicated that 1) the levee breach appeared at overflow depth more than 0.5m, corresponding to the previous studies, and 2) degree of the levee damages was not appreciably related to the covering conditions of top and slopes of levees.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.71.i_1285
  DOI：https://doi.org/10.2208/jscejcei.73.i_53_references_DOI_2uP1Oixs4WypQqvlAO2OWQiNFKV
  DOI ID：10.2208/jscejhe.71.i_1285, ISSN：1880-8751, eISSN：2185-467X, CiNii Articles ID：130005123444, CiNii Books ID：AN10426673
• Geometrical characteristic of scour holes caused by overtopping flow of embankment covered with different lengths of protection works
  八木澤 順治
  Journal of Japan Society of Civil Engineers, Ser.B1(Hydraulic Engineering), 巻：71, 2015年, ［査読有り］
  研究論文（学術雑誌）
• Investigation of scouur pattern downstream of levee toe due to overtopping flow
  八木澤 順治
  Journal of Japan Society of Civil Engineers, Ser.B1(Hydraulic Engineering), 巻：71, 2015年, ［査読有り］
  研究論文（学術雑誌）
• Return period of flood disturbance that increases diversity on gravel bars in middle stream of rivers　　　　　　　　　　　　　　　
  Kasun De Silva; Norio Tanaka; Junji Yagisawa
  LANDSCAPE AND ECOLOGICAL ENGINEERING, 巻：11, 号：1, 開始ページ：1, 終了ページ：18, 2015年01月, ［査読有り］
  Although medium-class flood disturbance is highly correlated with diversity of vegetated area of river habitat, it is still not clearly defined due to its complexity. To describe flood disturbance characteristics, two indices, breakage or overturning index and washout index, are used to express the breaking condition of trees and washout condition of trees and grasses. The relationship between diversity index of vegetated area (DI), calculated using vegetation species maps, and flood disturbance index (I (i) ), which represents the expected value of different flood disturbances, was investigated on four gravel bars in the Karasugawa River, Japan. The flood disturbance indices in Region A (high possibility to be a forest) and Region E (high possibility to be a bare area, as defined in this study) are identified as indicators for medium-class flood disturbance in this study. Moreover, this study confirms the results of previous studies on the Arakawa and Tamagawa Rivers, Japan, and their applicability to other rivers. In addition, the relationship between flood disturbance and DI in Region A or E explains the effect of flow regulation by construction of dams and weirs in river upstream on the downstream river habitat. Furthermore, based on the observed data and calculated results related to the possibility of vegetation and bare area on gravel bars in all investigated rivers, a range of flood return periods for medium-class flood disturbance for habitats on gravel bars was defined as 3-12.5 years, where the lower and upper values are related to the possibility of the presence of vegetation and the possibility of being a bare area, respectively.
  SPRINGER JAPAN KK, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11355-013-0229-4
  DOI ID：10.1007/s11355-013-0229-4, ISSN：1860-1871, eISSN：1860-188X, Web of Science ID：WOS:000349005200001
• Combined effects of coastal forest and sea embankment on reducing the washout region of houses in the Great East Japan tsunami　　　　　　　　　　　　　　　
  Norio Tanaka; Satoshi Yasuda; Kosuke Iimura; Junji Yagisawa
  JOURNAL OF HYDRO-ENVIRONMENT RESEARCH, 巻：8, 号：3, 開始ページ：270, 終了ページ：280, 2014年08月, ［査読有り］
  Coastal vegetation is widely recognized for its ability to reduce tsunami damage; however, coastal forests in large areas of the Tohoku and Kanto districts of Japan were destroyed by the Great East Japan tsunami on 11 March 2011. To elucidate the tsunami-mitigating effect of a coastal forest during a destructive tsunami, the combined effects of sea embankment and coastal forest were analyzed using post-tsunami survey data of the damage and a nonlinear long wave equation model that includes the breaking or washout condition of trees. The numerical simulations estimated that a 600-m-long coastal forest reduced the washout region of houses due to a 10-m-high tsunami at the coast by approximately 100 m, and the reduction achieved by a sea wall of approximately 5.4-6.4 m in height was approximately 560-1520 m, The height of a sea embankment or wall with sand dunes greatly affects the breaking condition of trees behind it by changing the tsunami flux overflowing the sea wall and the sand dune. For the combination of a sea embankment and a coastal forest during a destructive tsunami, the tsunami mitigation function of the coastal forest has an optimum value when the fluid force on the trees is strong but not strong enough to break the trees under the condition at which the tsunami overflows the sea embankment. At the investigated site, the effect of the coastal forest was larger than that of the sea embankment under optimal conditions. Thus, a coastal forest on a sand dune should be designed as a mitigation measure behind a sea embankment and optimally designed to protect the houses that are not protected from a tsunami by the sea embankment alone. (C) 2013 International Association for Hydro-environment Engineering and Research, Asia Pacific Division. Published by Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jher.2013.10.001
  DOI ID：10.1016/j.jher.2013.10.001, ISSN：1570-6443, eISSN：1876-4444, Web of Science ID：WOS:000345488000010
• 洪水減水波形と砂礫州の形状特性による土砂堆積特性を考慮した砂礫州の樹林化評価　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 大塚 翔平
  土木学会論文集Ｂ１（水工学）, 巻：70, 号：3, 開始ページ：60, 終了ページ：70, 2014年
  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，植生破壊・流失評価指標に加え細粒成分の堆積に関する指標を導入し，その有効性について検討した．土砂堆積指標SLIは，低水路との比高差が大きい場合は，砂礫州の流下方向長さが大きい場合（タイプ1）でも小さい場合(タイプ2)でも，細粒分の堆積範囲を示せる可能性があるが、比高差も流下方向長さも小さな砂礫州（タイプ3)や，植生群落が過剰に存在する砂礫州（タイプ4）に対しては，堆積の有無を評価できない傾向が見られた．砂礫州の切下げが実際された本田地先の砂礫州（タイプ1）での検討より，砂礫州の切下げによるSLIの変化と実際の細粒成分の堆積および植生繁茂状況が対応していることから，切り下げ後の土砂堆積および植生動態状況をSLIによって把握できる可能性を示した．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.70.60
  DOI：https://doi.org/10.2208/journalofjsce.10.1_19_references_DOI_HaEyKnn9VgWdlUajsGOtLsc1iFA
  DOI ID：10.2208/jscejhe.70.60, eISSN：2185-467X, CiNii Articles ID：130004691650
• 洪水時における砂礫州上の土砂堆積とそれに応じた植生遷移を考慮した植生動態モデルの開発　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫
  土木学会論文集Ｂ１（水工学）, 巻：70, 号：3, 開始ページ：71, 終了ページ：81, 2014年
  河道内砂礫州の植生繁茂状況の評価手法として，破断・倒伏後の木本の再生長・群落拡大特性，土砂堆積指標(SLI)を用いた細粒成分の堆積が遷移の早期化に及ぼす影響を考慮した植生動態モデルを開発した．荒川の熊谷大橋上流砂礫州(KU)にてモデルを構築し，荒川大橋上流砂礫州(AR)においてモデルの検証を行った．細粒成分の堆積が遷移の早期化に及ぼす影響を考慮したモデル化を加えた場合，KUでは，植物の破壊機構のモデル化のみでは再現できなかった河岸際の樹木群の侵入・定着を評価できた．本モデルをARに適用したところ，裸地域，シナダレスズメガヤ・ハリエンジュ群落の分布，繁茂面積を実測に近い形で評価できた．細粒成分の堆積とそれに伴う遷移速度の変化を考慮することが中長期の植生動態の評価に重要であることが示唆された．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.70.71
  DOI：https://doi.org/10.2208/jscejj.23-00264_references_DOI_RrbUZDBOxvGBCPB67wCRstIBHrd
  DOI ID：10.2208/jscejhe.70.71, eISSN：2185-467X, CiNii Articles ID：130004691651
• 射流中の角柱体に作用する抗力および周辺の底面せん断力に関する実験的研究　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫
  土木学会論文集Ｂ１（水工学）, 巻：69, 号：4, 開始ページ：I_685, 終了ページ：I_690, 2013年
  Many houses were broken and washed out by the supercritical tsunami flow overflowed from river embankment. Under the supercritical flow, drag force characteristics of dense obstacles and bed shear stress around them have not been clarified. Therefore, the objective of this study is to find out the effect of spacing of neighboring obstacles on the drag characteristics of quadratic prisms (house model) and bed shear stress distribution around them. Drag force acting on the house model and bed shear stress were measured by force gauge and shearing strain sensor, respectively. Four cases for different overflow depth and three cases for different G/bh (where, G and bh is horizontal spacing of each house model and width of a house model, respectively) were conducted. Drag force acting on the house model and bed shear stress between two house models (tm) increased with narrowing G. When G/bh=0.4, drag force and tm became 1.6 and 1.4 times comparing with single house model, respectively. However, when G/bh=1.2, drag force and shear stress became almost the same with single house case.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejhe.69.i_685
  DOI：https://doi.org/10.2208/jscejusr.78.1_1_references_DOI_P0vRW1Fj4XOXBiehimLeLCLrofi
  DOI ID：10.2208/jscejhe.69.i_685, eISSN：2185-467X, CiNii Articles ID：130004558043
• Effects of local scouring and saturation of soil due to flooding on maximum resistive bending moment for overturning Robinia pseudoacacia　　　　　　　　　　　　　　　
  M. B. Samarakoon; Norio Tanaka; Junji Yagisawa
  LANDSCAPE AND ECOLOGICAL ENGINEERING, 巻：9, 号：1, 開始ページ：11, 終了ページ：25, 2013年01月, ［査読有り］
  The effects on Robinia pseudoacacia (an exotic and invasive plant in Japanese rivers) of local scouring and saturation of the soil in the root-anchoring zone due to flooding were investigated. Scouring has been defined as the removal of substrate in the root-anchoring zone, exposing the tree roots. Tree-pulling experiments were conducted, simulating flood action, and the resulting damage was examined in order to assess the effect of local scouring on the maximum resistive bending moment (M (max)) for overturning. Scouring was artificially created to three different depths, 0, 25, and 50 cm. A nonlinear model was developed that included soil strength characteristics to calculate the critical overturning moment (M (cri)) under dry and saturated soil conditions. Significant correlations (p < 0.05) of M (max) with different tree and root-soil plate characteristics, such as diameter at breast height (D (bh)), tree weight, root depth, and root-soil plate radius, were developed in order to elucidate the effects of scouring on M (max). M (max) was slightly reduced with scouring depth for trees with D (bh) < 10 cm (small) trunks, and it was significantly and negatively (p < 0.05) correlated with scouring depth for trees with 10 < D (bh) < 20 cm (medium) trunks. However, M (max) did not change significantly with scouring depth for trees with a D (bh) > 20 cm (big) trunks. The nonlinear model was useful for determining the M (cri) of R. pseudoacacia under dry and saturated soil conditions. The overturning moments of all (small, medium, and big) trees were considerably reduced under the saturated soil condition. It could be concluded that medium-sized trees were greatly affected by scouring, and that small and big trees were mainly affected by saturation of the soil under severe flooding conditions.
  SPRINGER JAPAN KK, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11355-011-0169-9
  DOI ID：10.1007/s11355-011-0169-9, ISSN：1860-1871, eISSN：1860-188X, Web of Science ID：WOS:000313809900002
• Breaking pattern and critical breaking condition of Japanese pine trees on coastal sand dunes in huge tsunami caused by Great East Japan Earthquake　　　　　　　　　　　　　　　
  Norio Tanaka; Junji Yagisawa; Satoshi Yasuda
  NATURAL HAZARDS, 巻：65, 号：1, 開始ページ：423, 終了ページ：442, 2013年01月, ［査読有り］
  Coastal vegetation is widely recognized to reduce tsunami damage to people and buildings, and it has been studied recently because it requires relatively little capital investment compared with artificial measures, provides human-friendly beach fronts, and enhances inter-relationships with other ecological systems. However, the tsunami caused by the Great East Japan Earthquake at 14:46 JST on March 11, 2011, with a magnitude of 9.0 and epicenter 129 km east of Sendai, broke most of the sea wall (tsunami gates, large embankments) and caused catastrophic damage to coastal forests in the Tohoku and Kanto districts of Japan. A field survey was conducted to elucidate the critical breaking condition of Japanese coastal pine trees. Tree-trunk breakage was observed when the sea embankment was washed out or when there was no sea embankment and the tree was under strong inertia force or impact force by debris. Even though the trunk bending and breaking phenomena are different, statistical analysis showed that the critical diameters for trunk bending and trunk breaking were not very different. The overturning phenomenon is a little more complex than trunk breaking because the resistive force is a function of the substrate and root anchorage. An equation to determine the critical diameters for trunk bending, trunk breaking, and overturning was derived as a function of tsunami water depth, soil-root strength, and the hydrodynamic parameter (H (D) ) formulated by Froude number, drag coefficient, and the ratio of impact force to drag force considering the physical mechanisms to resist the tsunami. Trunk bending and breaking were closely related to tsunami water depth and the hydrodynamic parameter (H (D) ), but tree overturning was found to be more site specific, and the root-soil strength greatly affected the critical value. The proposed critical diameter equation and its coefficient are useful for the design of an inland forest of pine trees that can trap large trees, cars, debris, etc., to its breaking limit. The trapping function should be utilized more in the future designs of inland forests, if possible, on embankments.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11069-012-0373-4
  DOI ID：10.1007/s11069-012-0373-4, ISSN：0921-030X, eISSN：1573-0840, Web of Science ID：WOS:000312087100025
• EFFECTS OF UNDERSCOUR DEPTH AND HORIZONTAL SPACING BETWEEN TWO BED PROTECTION BLOCKS ON STABILITY OF FRONTAL BLOCK　　　　　　　　　　　　　　　
  Prem Shah; Norio Tanaka; Junji Yagisawa
  JOURNAL OF HYDRODYNAMICS, 巻：24, 号：4, 開始ページ：579, 終了ページ：588, 2012年09月, ［査読有り］
  The stability of a river-bed protection block in a flood event is affected by underscouring of the block. The effects of block spacing on block stability were investigated in different underscour conditions. Three blocks were placed at the bottom in a flume, and the underscour depth of the frontal block and distance between the first and second blocks were changed. Drag and lift forces were measured directly in each experimental condition. Particle Image Velocimetry (PIV) was used to visualize the flow and evaluate the streamline pattern. Pressure measurements around the block to understand the pressure distribution show that the pressure distribution on the rear and bottom surfaces of the block is significantly affected by changes in block spacing and underscour depth. The experimental results show that for the same underscour gap, lift, and drag coefficients decreased with increasing space between the two blocks. In addition, if the underscour gap is increased with the same horizontal spacing, the lift coefficient increases and drag coefficient decreases. These results demonstrate that wider spacing enhance stability of the frontal block in the underscour condition. Moreover, analysis of block stability with changing underscouring and horizontal spacing shows that bed protection blocks seem to have more stability when the gap between two bed protection blocks was equal to height of the blocks.
  ELSEVIER SCIENCE INC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/S1001-6058(11)60280-1
  DOI ID：10.1016/S1001-6058(11)60280-1, ISSN：1001-6058, eISSN：1878-0342, Web of Science ID：WOS:000308803200013
• 津波による海岸林および流失家屋が家屋被害に与えた影響　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 飯村 耕介; 近藤 康太
  土木学会論文集Ｂ２（海岸工学）, 巻：68, 号：2, 開始ページ：I_301, 終了ページ：I_305, 2012年
  Coastal forests in large areas of the Tohoku and Kanto districts of Japan were destroyed by the tsunami after the Great East Japan Earthquake on 11 March 2011. A non-linear long wave model that includes the breaking and washout condition of trees and houses estimates the capacity of a coastal forest with 590m in width to reduce the moment of fluid force behind forest and the washout region of houses by around 110m. On the other hand, even the washed out sea embankment has been found to contribute for reducing the washout region of houses by 1520m. Washed out houses applied additional drag force on downstream houses, however it also reduces the washout region by 510m because of the resistance to tsunami current even after the houses were broken and floated.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/kaigan.68.i_301
  DOI ID：10.2208/kaigan.68.i_301, ISSN：1884-2399, eISSN：1883-8944, CiNii Articles ID：130004550783, CiNii Books ID：AA12508551
• Index of medium-class flood disturbance for increasing diversity of vegetation area at gravel bars or islands in middle of rivers　　　　　　　　　　　　　　　
  Norio Tanaka; Junji Yagisawa
  International Journal of River Basin Management, 巻：10, 号：3, 開始ページ：255, 終了ページ：267, 2012年, ［査読有り］
  To elucidate the relationship between biodiversity on gravel islands in a river and flood disturbance characteristics, wash-out conditions of trees and perennial grasses and breaking conditions of trees were analysed and the applicability of these indices was investigated. Two indexes are defined to express breaking and wash-out conditions of trees, breaking or overturning index (BOI) and wash-out index (WOI), respectively, and one index, WOI50, is used to express the removal condition of annual grasses. Using WOI, WOI50, and BOI, this study classified the habitats on gravel islands into five regions. The relationship between the diversity of vegetation area calculated by the vegetation species map in this study, and the flood disturbance index, a kind of probability expectation value of area for each region integrated from 2- to 40-year return periods of floods disturbance, was analysed on six gravel islands in the Arakawa and Tamagawa rivers. Within the five regions (Regions A-E), important trends were found for three regions. The diversity of vegetated areas in the gravel river habitat increased with increasing Id, the flood disturbance index in Region D, which expresses a flood disturbance that can break trees and move medium-size gravel. However, the diversity index has peak values for Ia and Ie, the flood disturbance indices in Regions A and E, respectively, where Ia can express the immobility of gravels and lack of damage to trees and Ie can express the mobility of large-size gravel and the wash-out condition of vegetation. The indices Ia and Ie may describe a medium-class disturbance to the habitat on gravel islands in the middle of a river. © 2012 International Association for Hydro-Environment Engineering and Research.
  TAYLOR & FRANCIS LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15715124.2012.681661
  DOI ID：10.1080/15715124.2012.681661, ISSN：1571-5124, eISSN：1814-2060, SCOPUS ID：84870362288, Web of Science ID：WOS:000212537000004
• Characteristics of damage due to tsunami propagation in river channels and overflow of their embankments in Great East Japan Earthquake　　　　　　　　　　　　　　　
  Norio Tanaka; Junji Yagisawa; Satoshi Yasuda
  International Journal of River Basin Management, 巻：10, 号：3, 開始ページ：269, 終了ページ：279, 2012年, ［査読有り］
  The tsunami caused by the Great East Japan Earthquake on 11 March 2011, with a magnitude of 9.0, broke most of the sea embankment and coastal vegetation belt and caused catastrophic damage to people and buildings in the Tohoku and Kanto regions of Japan. A field survey was conducted to elucidate the damage to river embankments and their hinterlands (residential area) by tsunami propagation in river channels and overtopping of embankments. Two, three, and four rivers in Iwate Pref., Miyagi Pref., and the Kanto region, respectively, were selected for the field investigation. In the hinterlands, the tsunami came from two directions, coast and river, and the situation, including the evacuation of people, became complex. Therefore, it is necessary to identify locations of river embankments that can be easily overtopped by a tsunami in different tsunami conditions. Tsunami inundation patterns were classified by the river capacity and whether a river or sea embankment was breached or not. This will provide useful information for making new hazard maps and planning new cities. © 2012 International Association for Hydro-Environment Engineering and Research.
  TAYLOR & FRANCIS LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15715124.2012.694365
  DOI ID：10.1080/15715124.2012.694365, ISSN：1571-5124, eISSN：1814-2060, SCOPUS ID：84870307329, Web of Science ID：WOS:000212537000005
• Effects of root architecture, physical tree characteristics, and soil shear strength on maximum resistive bending moment for overturning Salix babylonica and Juglans ailanthifolia　　　　　　　　　　　　　　　
  Norio Tanaka; M. B. Samarakoon; Junji Yagisawa
  LANDSCAPE AND ECOLOGICAL ENGINEERING, 巻：8, 号：1, 開始ページ：69, 終了ページ：79, 2012年01月, ［査読有り］
  Effects of root architecture, physical tree characteristics, and soil shear strength on overturning moment due to flooding were investigated using Salix babylonica and Juglans ailanthifolia, exotic and invasive plants in Japanese rivers. Tree-pulling experiments that simulated flood action were conducted, and the resulting damage was examined to assess the effects of physical tree characteristics and root architecture on the maximum resistive bending moment (M (max)) for overturning. In situ soil shear strength tests were conducted to measure soil strength parameters. The effects of species differences on the M (max) were examined by analyzing root architecture. S. babylonica has a heart-root system that produces a greater overturning moment due to the strong root anchorage and the large amount of substrate that must be mobilized during overturning. J. ailanthifolia has a plate-root system that produces a smaller overturning moment. However, trees with the plate-root system may withstand overturning better due to an increased root:shoot ratio. The results of the study show that the M (max) of a tree for overturning had significant (P < 0.05) correlations with a tree's physical characteristics, including height (H), trunk diameter at breast height (D (bh)), D (bh) (2) , height multiplied by the second power of D (bh) (trunk volume index H x D (bh) (2) ), and root-soil plate depth (R (d)), and root-soil plate radius (R (r)). Considering the strategy of J. ailanthifolia to increase the root:shoot ratio for anchoring in the substrate, the trunk volume index (H x D (bh) (2) ) is a better parameter than D (bh) (2) because it indirectly involves the difference in below-ground volume and surface area. Different soil cohesion values were found at different experimental sites, and the average M (max) for overturning each species decreased linearly with increasing soil cohesion.
  SPRINGER TOKYO, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11355-011-0151-6
  DOI ID：10.1007/s11355-011-0151-6, ISSN：1860-1871, Web of Science ID：WOS:000298610300007
• Estimation of drag coefficient of a real tree considering the vertical stand structure of trunk, branches, and leaves　　　　　　　　　　　　　　　
  Norio Tanaka; Hiroshi Takenaka; Junji Yagisawa; Taiji Morinaga
  International Journal of River Basin Management, 巻：9, 号：3-4, 開始ページ：221, 終了ページ：230, 2011年, ［査読有り］
  Drag coefficients of a real tree trunk and branch and the sheltering effects of an upstream trunk or branch on a downstream one in a linear arrangement with different spacings were investigated in detail. Willow and Robinia pseudoacacia, representative and invasive trees in Japanese rivers, respectively, were selected for the study. The drag coefficient of the real tree trunk started to decrease from a relatively low Reynolds number and was smaller than that of a smooth circular cylinder in the entire Reynolds number range investigated. Leaves increased the drag coefficient by around 40–100% in comparison to that of a branch alone and increased with increasing the area ratio of leaves and branches. The sheltering effects of an upstream branch increased with the existence of leaves. The drag coefficient of a downstream branch approached around 95% of that of a single branch with increasing Reynolds number, regardless of the presence of leaves. The moment for drag force of a whole tree was calculated for a strong wind event that overturned trees in the Arakawa River, Japan. The calculated value was compared with the experimental threshold values and was validated within a reasonable limit. © 2011 International Association for Hydro-Environment Engineering and Research.
  TAYLOR & FRANCIS LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15715124.2011.606427
  DOI ID：10.1080/15715124.2011.606427, ISSN：1814-2060, eISSN：1814-2060, SCOPUS ID：84859899881, Web of Science ID：WOS:000212533100007
• Flow structures and sedimentation characteristics around clump-type vegetation　　　　　　　　　　　　　　　
  Norio Tanaka; Junji Yagisawa
  JOURNAL OF HYDRO-ENVIRONMENT RESEARCH, 巻：4, 号：1, 開始ページ：15, 終了ページ：25, 2010年04月, ［査読有り］
  Models comprising 7, 19, 37, or 61 equally spaced circular cylinders in a staggered hexagon-shape arrangement were mounted on a water-flume bed, and the characteristics of flow structures in uniform flow around the models were investigated to elucidate the effects of number, density, and the emergent or submerged condition of the cylinders as a model of clump-type roughness. Drag force was measured with changing both the relative optical gap (G/D) and relative height (h/H), where G is the optical gap between neighboring cylinders in cross-section, D is the cylinder diameter, h is the model height, and H is the water depth, and the drag coefficient C-d was calculated. The flow structure around the clump-type roughness models and the drag coefficients changed greatly with changing G/D. The number of cylinders in the clump-type model greatly affected the value of C-d when G/D was large, because the sheltering effect is changed with the number. Flow structures changed around G/D >1. The C-d in the emergent condition became slightly larger than that in the submerged condition but was not much changed in comparison with the G/D. Sedimentation around and behind vegetation was investigated in the field after a flood event. When the vegetation density was high (G/D < 0.5-1), such as with willow (Sa subfragilis) or dense grass (Eragrostis curvula, a clump-type vegetation), sedimentation occurred behind the vegetation region. When the vegetation density was low (G/D > 1), such as with Robinia pseudoacacia or Phragmites japonica, it occured inside the vegetation region. The flume experiment and field study indicate that the flow pattern changes depending on the G/D with a wide range of Reynolds numbers and that it affects the sedimentation pattern at an actual flood event. (C) 2009 International Association for Hydro-environment Engineering and Research, Asia Pacific Division. Published by Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jher.2009.11.002
  DOI ID：10.1016/j.jher.2009.11.002, ISSN：1570-6443, eISSN：1876-4444, Web of Science ID：WOS:000281648600003
• Flood wash-out conditions of an exotic and invasive plant, Eragrostis curvula, in Arakawa River, Japan　　　　　　　　　　　　　　　
  Junji Yagisawa; Norio Tanaka
  International Journal of River Basin Management, 巻：8, 号：1, 開始ページ：15, 終了ページ：24, 2010年03月, ［査読有り］
  The effect of an exotic and invasive plant, Eragrostis curvula, on the threshold of gravel movement and wash-out conditions of the plant due to flood was investigated in the midstream Arakawa River, Japan. Under various hydraulic conditions (grain diameter, bed slope, and water depth) and plant growth characteristics (clump diameter and plant density), the Shields parameter of the gravel in the plant-vegetated area was estimated using the drag characteristics of the plant measured directly in field and wind tunnel experiments, and the plant's effect on friction velocity was evaluated. The removal threshold of E. curvula could be defined when the friction velocity around the plants was equal to the critical friction velocity of d84 grain diameter at which 84% volume passed through the sieve. The threshold condition was found to be well expressed by the relationship between the bed slope direction component of the water weight and the drag characteristics due to the plant MDc1.5, where M is the plant density and Dc the clump diameter of E. curvula. © 2010 International Association for Hydro-Environment Engineering and Research.
  TAYLOR & FRANCIS LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15715121003715057
  DOI ID：10.1080/15715121003715057, ISSN：1571-5124, eISSN：1814-2060, SCOPUS ID：77954852842, Web of Science ID：WOS:000212527900003
• 樹木の洪水破壊指標と流失指標を考慮した砂礫州上樹林地の動態評価手法の提案　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 福岡 捷二
  土木学会論文集Ｂ, 巻：66, 号：4, 開始ページ：359, 終了ページ：370, 2010年
  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．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejb.66.359
  DOI：https://doi.org/10.2208/jscejj.23-00264_references_DOI_ZjZHof5RltazodfDip0JRZp1OiA
  DOI ID：10.2208/jscejb.66.359, eISSN：1880-6031, CiNii Articles ID：130004468118
• FLOW STRUCTURES AND SEDIMENTATION CHARACTERISTICS AROUND COLONY-TYPE VEGETATION AT FLOOD EVENTS　　　　　　　　　　　　　　　
  Norio Tanaka; Shiho Ito; Junji Yagisawa
  ADVANCES IN WATER RESOURCES AND HYDRAULIC ENGINEERING, VOLS 1-6, 開始ページ：981, 終了ページ：986, 2009年, ［査読有り］
  Colony models, comprising seven equally spaced cylinders with staggered arrangement are mounted on a water flume bed. The characteristics of flow structures around the colony-type roughness model in uniform flow were investigated. For elucidating the effects of the vegetation density and emergent or submerged condition of the colony-type roughness according to the flood water depth, drag force is measured with changing both of the relative space L/d and the relative height h/H,where L is the space between neighbored cylinders, d is the cylinder diameter, h is the model height and H is the water depth and the drag coefficient (C(d)) is calculated. The flow structure around the colony models and the drag coefficients values are changed depending on L/d and h/H. Two types of flow structures, a large-scale Karman vortex street behind the colony models and a primitive Karman vortex street behind the individual cylinders are generated. The C(d) in emergent condition becomes larger than that in submerged condition. The C(d) increases sharply when h/H is ranged from 0.8 to 1.0 and then approaches the C(d) value in unsubmerged condition. In field observation, sedimentation around the two roughness type was investigated. When the vegetation density is large, like willow, i.e. Salix subfragilis or Eragrostis curvula (colony-type vegetation), the sedimentation is occurred behind the vegetatation region When vegetation denesity is small, it occurres inside the vegetation region, i.e., Robinia pseudo-acacia or Phragmites japonica. Similar flow structure are supposed to be occurred in water flume experiment and in field. This study elucidated the effect of vegetation density on flow structure.
  TSINGHUA UNIVERSITY PRESS, 英語, 研究論文（国際会議プロシーディングス）
  DOI：https://doi.org/10.1007/978-3-540-89465-0_172
  DOI ID：10.1007/978-3-540-89465-0_172, Web of Science ID：WOS:000268750700172

• 難侵食層がヘッドカット進行および堤体欠損に及ぼす影響　　　　　　　　　　　　　　　
  西川 咲良; 八木澤 順治
  河川技術論文集, 巻：27, 開始ページ：211, 終了ページ：216, 2021年
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.27.0_211
  DOI ID：10.11532/river.27.0_211, eISSN：2436-6714, CiNii Articles ID：130008113990
• 対照的な河床環境を有する流路におけるアユの生息地適性評価モデルの構築とそれに基づく予測精度の比較による河床環境の重要性の検討　　　　　　　　　　　　　　　
  宇佐美 将平; 八木澤 順治; 溝口 裕太; 小野田 幸生; 田代 喬; 宮川 幸雄
  河川技術論文集, 巻：26, 開始ページ：361, 終了ページ：366, 2020年
  For the evaluation of habitat suitability for fish, hydraulic data that can be easily observed have been
  often used. However, it has become essential to consider fish's preference for riverbed environments
  modified by artificial sediment supply in gravel-bed rivers. In this study, two types of evaluation methods
  were applied on the target river with different riverbed environment in the two diversion channels. These
  models are conventional evaluation method based on hydraulic quantity (HSI), and it taking into account
  the sand cover on stony riverbed as a riverbed environment in addition to the hydraulic quantity (HSIb). The
  prediction accuracy was elucidated by comparing the habitat suitability index calculated from these models
  with the spatial distribution of the focal point of Ayu obtained from the field survey. The evaluation of
  habitat suitability taking into account the degree of sand coverage (HSIb) was found to be able to evaluate
  the focal point of Ayu more accurately than the conventional method (HSI).
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.26.0_361
  DOI ID：10.11532/river.26.0_361, eISSN：2436-6714
• 堤防天端の縦断的な凹凸の周期性が越流時のガリー侵食に及ぼす影響　　　　　　　　　　　　　　　
  八木澤 順治; 正村 亮太
  河川技術論文集, 巻：26, 開始ページ：497, 終了ページ：502, 2020年
  At Typhoon No.19 in 2019, overtopping flow from embankment occurred at many locations in the Arakawa River tributaries, and gully erosions have been confirmed. In a previous study, the relationship between the wavelength of irregularities at crest of embankment and gully erosion was examined by laboratory experiments. However, since this experiment was conducted with the overflow water depth limited, the effect of changes in overflow depth on gully erosion characteristics has not been clarified. Therefore, the objectives of this study are 1) to clarify the effect of increasing overflow depth on the gully erosion characteristics by hydraulic experiment, and 2) to confirm the similarity between gully erosion characteristics obtained by experiments and actual phenomena in the field. As a results of hydraulic experiment and field survey, it was confirmed that dimensionless erosion depth and interval of neighboring gully erosions were similar to the experimental values.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.26.0_497
  DOI ID：10.11532/river.26.0_497, eISSN：2436-6714
• 水害時における調査方法の標準化および共通 データベース構築に向けたガイドラインの提案　　　　　　　　　　　　　　　
  呉 修一; 大槻 順朗; 八木澤 順治; 永野 博之; 二瓶 泰雄
  河川技術論文集, 巻：23, 開始ページ：67, 終了ページ：72, 2017年
  The frequency and magnitude of the water-related disasters have been increasing all over the world. Several organizations including JSCE flood disaster investigation team generally conduct an on-site survey after severe disasters in order to clarify the damage mechanism. However, there is no solid guideline for the river flood disaster in Japan, whereas the tsunami disaster. This report provides essential information of a proposed guideline for standardization of an on-site field survey and data treatment for flood disaster. We especially focused on ways to identify inundation marks (depth or height) and to evaluate building damage and bank failure. For surveyor’s convenience and safety, the guideline includes concrete cases with many example photos and useful data sheets. The guideline also deals with a simple and fast data sharing method with Google My Map service, a tool for data combination of field data and photos developed on Excel VBA and secure data sharing method provided by JSCE.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.23.0_67
  DOI ID：10.11532/river.23.0_67, eISSN：2436-6714
• 水害調査方法の標準化に向けて : 家屋被害分類—Toward standardization of on-site surveys of river flood disasters : damage classification of residential houses　　　　　　　　　　　　　　　
  呉 修一; 八木澤 順治; 大槻 順朗
  東北地域災害科学研究 = Tohoku journal of natural disaster science / 自然災害研究協議会東北地区部会, 日本自然災害学会東北支部 編, 巻：52, 開始ページ：55, 終了ページ：60, 2016年03月
  仙台 : 東北大学災害科学国際研究所東北地区自然災害資料センター, 日本語
  CiNii Articles ID：40020760182, CiNii Books ID：AN00352457
• 平成27年9月関東・東北豪雨において鬼怒川他支川で生じた破堤現象と落堀について　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 五十嵐 善哉; 山岸 玄弥
  河川技術論文集, 巻：22, 開始ページ：333, 終了ページ：338, 2016年
  For clarifying the scoured characteristics around levee breaching point at the 2015 Kanto & Tohoku heavy rain, post flood survey was conducted not only for the Kinugawa River but other rivers in Ibaraki Prefecture where levee breaching was occurred, and the breaching length and the depth of the scoured region were investigated with the hydraulic parameters. Flume experiment was also conducted in a flume with 1/60 scale. The levee shape were selected as the full shape and the half-scoured levee shape. Clear water scour condition was set at the downstream of the levee. The number of scoured region for the full shape levee condition were around 5-8, and is similar to the actual situation at the breaching point of the Kinugawa River. The scoured depth for half scoured levee shape was 1.5-1.8 times larger for full-size embankment case. The breaching widths for Miyato, Nishinire, and Hachikenbori River, were relatively small, but was similar to the initial breaching width of the Kinugawa River.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.22.0_333
  DOI ID：10.11532/river.22.0_333, eISSN：2436-6714
• 二瀬ダム下流の粗粒化河道におけるダム還元土砂の動態評価　　　　　　　　　　　　　　　
  竹澤 祥太; 田中 規夫; 八木澤 順治; 本戸 卓美
  河川技術論文集, 巻：21, 開始ページ：115, 終了ページ：120, 2015年
  For improving river environment, artificial sand supply is recently conducted in downstream of dam reservoirs. However, there are many unknowns regarding how the sediment supply affects the bed material size and its dynamics at a flood event. Therefore, the purpose of this study is to clarify quantitatively the dynamics of artificial supplied sand in armored bed by proposing new model for calculating bed shear stress in the cobble layer. Quasi-three dimensional model has been developed considering the sheltering effect by boulders and decrease of bed shear stress. 2D model and the quasi 3D model are compared at flood events in downstream of the Futase Dam. Dynamics of sedimentation height and the deposited mean diameter were analyzed in the simulation. The quasi 3D model can express well the sedimentation at an inner side of meandering part of the river. The size of deposited material in gravel layer is more than 4cm. The model has a possibility to express the dynamics of supplied sediment motion in armored rivers.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.21.0_115
  DOI ID：10.11532/river.21.0_115, eISSN：2436-6714
• 砂礫州切り下げ後の長期植生動態解析に基づく樹林化抑制効果の確率論的検討　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫
  河川技術論文集, 巻：21, 開始ページ：319, 終了ページ：324, 2015年
  As one of the countermeasures for the forestation on gravel bars, excavation of gravel bars is recently conducted. To conduct effective excavation for preventing re-forestation during long term, stochastic analysis is needed considering various flow discharge condition. Therefore, objective of this study is to clarify the effect of forestation due to the excavation of the gravel bar. To fulfill the objective, the long term growth dynamic model was used for evaluating the possibility of forestation under various discharge condition. The developed model was applied to gravel bar at Honda in Arakawa River. Expected value of forestation (EV) was defined and its value was calculated in each excavation type. As a comparison of EV in each excavation type, EV value for Case 6 which gravel bar is excavated diagonally, becomes smallest. It is indicated that developed model can evaluate the suitable excavation type for preventing re-forestation on the gravel bar.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.21.0_319
  DOI ID：10.11532/river.21.0_319, eISSN：2436-6714
• 堆積土砂の再移動を考慮した切り下げ直後の砂礫州の再樹林化評価に関する研究　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 大塚 翔平; 廣野 太志; 竹島 睦
  河川技術論文集, 巻：19, 開始ページ：387, 終了ページ：392, 2013年
  For clarifying the possibility of forestation in gravel bed bars or islands, sediment load change index (SLI) has been proposed considering deposition and washout of fine sand during flood discharge is declined. The applicability of this index was validated in the middle stream reach of the Oppe River and the Arakawa River. Before and after typhoons in 2007, 2011 and 2012, field investigations were conducted on five gravel bars in two rivers. River flow was also analyzed by two-dimensional depth-averaged Reynolds equations, and SLI was calculated. In comparison with SLI and sand deposition situation on observed gravel bars, SLI has been found to express well the sand deposition situation on most of observed gravel bars. However, when this method is applied to the gravel bar which has small relative height from low channel or long distance along the flow direction, SLI could not express well the actual deposition situation. The effect of the excavation of gravel bar was investigated at Honda location in the Arakawa River through SLI. The re-colonization of the grass-type vegetation can be confirmed at the location where SLI becomes higher due to the excavation. This result indicates SLI is suitable parameter for evaluating the effectiveness of the excavation of the gravel bar.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.19.0_387
  DOI ID：10.11532/river.19.0_387, eISSN：2436-6714
• 河道内植生の洪水による破壊および破壊規模に応じた再生・拡大過程を考慮した植生動態モデルの開発　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫; 福岡 捷二
  河川技術論文集, 巻：19, 開始ページ：393, 終了ページ：398, 2013年
  A dynamic model for predicting the long term change of vegetated area in river was developed when the flood does not change the morphology of the gravel bar. In this simulation model, the expansion, destruction due to floods and regeneration of the plants were considered. In this study, the wash-out of plants and tree trunk breakage were considered as the destruction mechanism of the river vegetation due to floods. For elucidating the characteristics of regeneration of tree type vegetation, tree regeneration situation after 1year of the 2006 and 2007 flood event was investigated in the Arakawa River. The simulation model was applied to the middle stream reach of the Arakawa River for validating the change of vegetated area from 2000 to 2012. This model expressed the situation of vegetated area in 2012 within the reasonable limit. Especially, this model can be found to describe the location of each vegetation and expansion area of woody type vegetation by considering the tree’s regeneration and expansion after the trunk bending or breaking damage by floods.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.19.0_393
  DOI ID：10.11532/river.19.0_393, eISSN：2436-6714
• 洪水中の樹木破壊・流失と河床変動を考慮した流れの準三次元解析手法の適用性　　　　　　　　　　　　　　　
  森永 泰司; 八木澤 順治; 田中 規夫; 内田 龍彦
  河川技術論文集, 巻：18, 開始ページ：77, 終了ページ：82, 2012年
  For the management of river channel, it is very important to estimate correctly the change of river bed topography at a flood event. However, the bed variation is quite difficult to predict for the river where forestation occurs because of the change of vegetation resistance during a flood. The new method is proposed in this study to evaluate the bed variation around a forest on a gravel bar at large flood event. River bed variation analysis was conducted for the middle stream region of Arakawa River using quasi-three dimensional flow model combined with the new method that includes the washout and breaking condition of trees. Observed amount of bed variation was reproduced well by the model considering the washout and breaking condition of trees during a flood. On the other hand, the difference is small on the calculated river bed variation between the quasi-three dimensional and two-dimensional method. This result indicates that the improvement of vegetation resistance change during a flood event is important for the accurate evaluation of river bed variation at a large flood event that can washout or break trees.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.18.0_77
  DOI ID：10.11532/river.18.0_77, eISSN：2436-6714
• 東日本大震災における津波の河川遡上による堤防越流と被害状況の把握　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 佐藤 誠幸; 細萱 陽
  河川技術論文集, 巻：18, 開始ページ：357, 終了ページ：362, 2012年
  The tsunami caused by the Great Japan Earthquake on 11 March 2011, broke most of the sea embankment and coastal vegetation belt and caused catastrophic damage to people and buildings in the Tohoku and Kanto regions of Japan. Field surveys were conducted to elucidate the damage to river embankments and their hinterlands (residential area) by tsunami propagation in river channels and overtopping of embankments. Ten rivers were selected for the field investigation. In the hinterlands where overtopping occurred, the tsunami came from two directions, coast and river. It is necessary to identify locations of river embankments that can be easily overtopped by a tsunami in different tsunami conditions, river morphology and inland embankment of roads or trains. Tsunami inundation patterns were classified by the river capacity and whether a river or sea embankment was breached or not. This will provide useful information for making new hazard maps and planning new cities. Numerical simulation in Abukumagawa River shows the clear relationship between the scoured area and the tsunami overtopping time.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.18.0_357
  DOI ID：10.11532/river.18.0_357, eISSN：2436-6714
• 土砂堆積指標を考慮した砂礫州の樹林化評価に関する研究　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫; 福岡 捷二
  河川技術論文集, 巻：18, 開始ページ：65, 終了ページ：70, 2012年
  For evaluating the possibility of forestation in gravel bed bars, sediment deposition index (SDI) was derived considering the characteristic of flood hydrograph. The applicability of this index was validated in the middle stream reach of the Oppe River and the down stream reach of the Tamagawa River. Before and after typhoon No.12 and 15 on 2011, field investigations were conducted on gravel bars in Tamagawa and Oppe River. For above two floods, river flow was analyzed by two-dimensional depth-averaged Reynolds equations, and SDI and WOI (Washout index proposed by Tanaka et al. (2010)) were calculated. Calculated SDI in numerical simulation and situation of sand deposition on observed gravel bars were compared. When the critical value of SDI was considered to be 0.7, SDI could express well the sand deposition situation on observed gravel bars. By using SDI-WOI plot, vegetated situation of grass type vegetation on gravel bars in Tamagawa River was classified well. Grass type vegetation has been found to grow only on where SDI is larger than 0.7 and WOI is smaller than 1.4. These results indicated SDI-WOI plot proposed in this study has some possibility to evaluate the location that grass type vegetation can grow easily.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.18.0_65
  DOI ID：10.11532/river.18.0_65, eISSN：2436-6714
• 砂礫州における生物多様度と相関性の高い洪水撹乱指標について　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 菊次 祐; 佐藤 貴紀; 福岡 捷二
  河川技術論文集, 巻：17, 開始ページ：227, 終了ページ：232, 2011年
  For elucidating the relationship between flood disturbance and biodiversity of vegetation in gravel bed bars, Breakage or Overturning Index (BOI) and Wash-Out Index (WOI) were derived considering the difference of vegetation breaking phenomena due to floods, i.e. trunk breakage or overturning, and wash-out of trees or grass, respectively. Coupling the two indices, the method for classifying the river habitat into five, not tree breaking and not washout (Region A), tree breaking and not washout (Region B), not tree breaking and washout (annual grass) (Region C), tree breaking and washout (annual grass) (Region D), and washout of all vegetation (Region E), is proposed. The condition at which WOI is larger than 0.5, and WOI is less than one, is correlated with the Shannon-Wiener index at three gravel-bed bars in the Arakawa River, Japan. Especially, when BOI is larger than one, the biodiversity is increased. For Region A and E, the trend is assumed to be affected by the duration after flood. The proposed index for Region D has possibilities to express middle class disturbance that is closely related to the biodiversity at the habitat.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.17.0_227
  DOI ID：10.11532/river.17.0_227, eISSN：2436-6714
• 地盤強度と根の形状特性が樹木転倒限界に与える影響について　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治
  河川技術論文集, 巻：第16巻, 開始ページ：225, 終了ページ：230, 2010年, ［査読有り］
  Tree pulling experiments that simulated flood action were conducted using Salix babylonica and Juglans ailanthifolia, exotic and invasive trees in Japanese rivers.. The resulting damage was examined in order to assess the effects of physical tree characteristics and root architecture on the maximum resistive bending moment (M_max) for overturning. In situ soil shear strength tests were conducted in order to measure soil strength parameters. Significantly correlated (p<0.05) non-linear relationships were found between M_max and tree characteristics, and H*D ² provided the best predictor of the Mwithin them. Non-linear models were fitted between M_max and D_bh for each species. The more efficient root architecture to withstand overturning is the heart-root system of S. babylonica, and the plate-root system of J. ailanthifolia is less efficient not with the same breast height diameter but with the same root volume. The average M_max of S. babylonica for overturning each species decreased linearly with increasing soil cohesion within the experimental range because root anchoring depth is restricted with increasing the soil cohesion.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.16.0_225
  DOI ID：10.11532/river.16.0_225, eISSN：2436-6714
• 東日本大震災における津波の河川遡上と越流による被害＜論文＞
  田中 規夫; 八木澤 順治; 安田 智史
  埼玉大学工学部紀要 第一部 論文集, 巻：44, 開始ページ：21, 終了ページ：24, 2010年
  The tsunami caused by the Great Japan Earthquake at 14:46 JST on 11 March 2011, with a magnitude of 9.0 and epicenter 129 km east of Sendai, broke most of the sea embankment and coastal vegetation belt and caused catastrophic damage to people and buildings in the Tohoku and Kanto districts of Japan. A field survey was conducted to elucidate the damage situation of residential region by tsunami propagation in river channels and its overtopping from embankment. Abukumagawa River, Nanakita River and Old Kitakamigawa River located on Miyagi prefecture were selected for field investigation. In Abukumagawa River and Old Kitakamigawa River, overtopping flow from embankment occurred mainly at the outer-bank side of meandering section. Severe erosion was occurred on levee slope and neighboring houses were washed out by the scouring due to the overtopping flow. The hinterlands of coast and river had tsunami from two directions, coast and river, and the damage situation including the evacuation action for people became complex. Therefore, it is necessary to elucidate the location where tsunami is easy to be overtopped for different tsunami conditions.
  埼玉大学工学部広報委員会, 日本語
  ISSN：1880-4446, CiNii Articles ID：120005386080
• Effects of tree characteristics and substrate condition on critical breaking moment of trees due to heavy flooding　　　　　　　　　　　　　　　
  Norio Tanaka; Junji Yagisawa
  巻：5, 号：1, 開始ページ：59, 終了ページ：70, 2009年02月
  To elucidate tree breakage conditions with different breaking mechanisms, i.e., moment by drag force, local scour, and degradation of the substrate around trees, field surveys were conducted after a flood event (September 2007 flood due to Typhoon 9) in the Tamagawa River, Japan. Trees in a river have two main breaking mechanisms during a flood event, moment by fluid force and erosion of the substrate. Moment by fluid force causes two breaking phenomena, trunk damage (bending, breakage) and overturning. Trunk bending or breakage can be expressed as a function of d (c) , where d is the trunk diameter at breast height and the power c equals 3 for trunk bending or breakage, and approximately 2 for overturning. Smaller diameter trees experienced trunk breakage, but larger trees were overturned. The range for these two breaking patterns changes with the substrate condition. If severe scouring has occurred, the threshold for overturning moment can be quite small. Tree overturning occurred mostly on the bank side of the gravel bar; however, some trees, especially Robinia pseudo acacia and Morus bombycis, were overturned if the substrate was a thin deposited soil or silt layer on gravel. The roots were anchored in the small-particle deposited layer in that case. As for the erosion of the substrate, the tree-breaking patterns can be classified into three types depending on the relationship between the nondimensionalized bed shear stress of d (50) and d (84), the representative grain diameters at which 50 and 84% of the volume of the material, respectively, is finer. The nondimensionalized shear stress of d (84) is an important parameter for discussing the rehabilitation of the gravel bed bar. The boundary region for tree overturning can be changed by the effects of plant cover and debris attachment.
  英語
  DOI：https://doi.org/10.1007/s11355-008-0060-5
  DOI ID：10.1007/s11355-008-0060-5, ISSN：1860-1871, Web of Science ID：WOS:000263118100006
• 護床ブロックの洪水に対する安定条件に関する研究　　　　　　　　　　　　　　　
  井上浩一; 田中規夫; 八木澤順治
  水工学論文集, 巻：53, 開始ページ：961, 終了ページ：966, 2009年
• 砂礫州上における繁茂場所の相違が樹木の洪水時流失限界に及ぼす影響　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治
  水工学論文集, 巻：53, 開始ページ：631, 終了ページ：636, 2009年
• 河道内植生の洪水による破壊・再生を考慮した植生動態モデルの開発　　　　　　　　　　　　　　　
  八木澤順治; 田中規夫
  水工学論文集, 巻：53, 開始ページ：1171, 終了ページ：1176, 2009年
• 護床ブロックの洪水に対する安定条件に関する研究　　　　　　　　　　　　　　　
  井上浩一; 田中規夫; 八木澤順治
  巻：53, 開始ページ：961, 終了ページ：966, 2009年
• 砂礫州上における繁茂場所の相違が樹木の洪水時流失限界に及ぼす影響　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治
  巻：53, 開始ページ：631, 終了ページ：636, 2009年
• 河道内植生の洪水による破壊・再生を考慮した植生動態モデルの開発　　　　　　　　　　　　　　　
  八木澤順治; 田中規夫
  巻：53, 開始ページ：1171, 終了ページ：1176, 2009年
• 砂礫州上樹木の破壊形態の相違を考慮した樹林化判定手法に関する研究　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫; 福岡 捷二
  河川技術論文集, 巻：15, 開始ページ：153, 終了ページ：158, 2009年
  For evaluating the difference of tree breaking phenomena due to floods, i.e. trunk breakage or overturning, and wash-out of trees, Breakage or Overturning Index(BOI)and Wash-Out Index (WOI) were derived respectively in this study. Based on these indices, the method for classifying the dynamics of forestation in rivers was proposed. This method was applied to the middle stream reach of the Arakawa River The situation of ’breaking’ or ’washing out’ on a gravel-bedbar after 2007 flood can be evaluated by using BOI and WOL In addition, in three locations where relative height from ordinary water level isdifferent, the relationships between flood return period and breaking mode of trees due to floods were demonstrated. At the location where relative height is the smallest, possibility of forestation should be low because wash-out of trees occurs by 5 to 10 years return period of floods. In contrast, possibility of forestation should be high at the location where relative heightis the biggest, because wash-out of trees doesn’t occur by 40 years return period of floods. This method is available to judge the area where artificial management of trees is required.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.15.0_153
  DOI ID：10.11532/river.15.0_153, eISSN：2436-6714
• 砂礫州上に繁茂する植生の洪水時流失限界評価　　　　　　　　　　　　　　　
  八木澤順治; 田中規夫; 福岡捷二
  河川技術論文集, 巻：14, 開始ページ：139, 終了ページ：144, 2008年
• 河道内樹木の洪水破壊形態と破壊限界値の基盤土壌条件による相違　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治; 佐々木寧; 福岡捷二
  水工学論文集, 巻：52, 開始ページ：649, 終了ページ：654, 2008年
  DOI：https://doi.org/10.2208/prohe.52.649
  DOI ID：10.2208/prohe.52.649
• 砂礫州上に繁茂する植生の洪水流出限界評価　　　　　　　　　　　　　　　
  八木澤順治
  河川技術論文集, 巻：14, 開始ページ：139, 終了ページ：144, 2008年
  Trees in rivers sometimes become driftwoods at flood events, and it might cause a disaster. It is important to understand the uprooting condition of the trees by floods. 2D unsteady depth-averaged flow model was applied to the Arakawa River between 76 km to 82 km for evaluating September 2007 flood and October 2006 flood. This model expressed well the peak water levels of the floods. Threshold drag moment and shear stresses for up-rooting the representative vegetation, Salix subfragilis and Robinia pseudoacacia, which grew on the gravel-bed bar in the upstream of the Kumagaya-Ohashi was evaluated according to the result of numerical analysis and the washed-out situation of the plants. Threshold drag moment for tree-uprooting on the gravel-bed was larger compared with the previous experimental results by pulling test. Flood discharge for which all plants on this gravel-bed bar were washed away was evaluated by comparing the calculated shear stress in each discharge condition and the threshold shear stress for uprooting obtained by the analysis.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.14.0_139
  DOI ID：10.11532/river.14.0_139, eISSN：2436-6714, CiNii Articles ID：10026287312
• 河道内樹木の洪水破壊形態と破壊限界値の基盤土壌条件による相違　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治; 佐々木 寧; 福岡 捷二
  水工学論文集, 巻：52, 開始ページ：649, 終了ページ：654, 2008年
  For elucidating tree breakage condition with different breaking pattern, i. e. trunk breakage, tree overturn, local scour and degradation of the substrate of trees, and with different tree species, field investigation on tree damage situation after two flood events (October 2006 flood and September 2007 flood) were conducted in the Arakawa River and the Tamagawa River. Plant regeneration situation after 1year of the 2006 flood event was also conducted. If the breaking pattern is bending or partial breakage, the tree, Salix subfragilis, has a high productivity for regrowth. It implies that such breaking pattern is not so important if we consider the rehabilitation of gravel-bed river environment. The threshold moment of partial overturn of Robinia pseudo-acacia that has thin root zone was smaller compared with the previous experimental results by pulling trees because of a local scour. If severe scouring was occurred, threshold overturning moment can be quite small. The threshold moment can be found to be expressed as a function of the substrate condition.
  公益社団法人 土木学会
  DOI：https://doi.org/10.2208/prohe.52.649
  DOI ID：10.2208/prohe.52.649, ISSN：0916-7374, eISSN：1884-9172, CiNii Articles ID：130004044087
• 砂礫州上樹木の洪水時破壊限界に関与する抗力モーメントと底面せん断力の評価＜研究成果報告＞　　　　　　　　　　　　　　　
  田中 規夫; 八木澤 順治
  埼玉大学工学部紀要. 第1部 論文集, 巻：42, 開始ページ：42, 終了ページ：43, 2008年
  This paper reports the research project in Arakawa River and Tamagawa River related to breaking condition of trees vegetated on gravel bars. Field surveys and laboratory experiments were conducted for elucidating the tree breaking condition due to the flood. The river flow analysis is also applied to the Arakawa River for evaluating the tree wash-out condition. The tree breaking and tree wash-out can be evaluated by drag moment acting on the tree trunk and the non-dimensionalized bed shear stress, respectively. The threshold drag moment and shear stress are discussed and the papers are introduced in this manuscript.
  埼玉大学工学部, 日本語
  DOI：https://doi.org/10.24561/00016427
  DOI ID：10.24561/00016427, CiNii Articles ID：120005386063
• 河道内樹木の洪水撹乱規模と樹齢による破壊限界変化　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治; 青木信哉; 福岡捷二
  河川技術論文集, 巻：13, 開始ページ：177, 終了ページ：182, 2007年
  For elucidating tree breakage condition with different tree species and tree age, field investigation on tree height h_v, trunk diameter at breast height d_BH, and tree projected area in vertical section, of Salix subfragilis and Robinia pseudoacacia were conducted on three gravel-bed bars in midstream of the Arakawa River. After a flood on October 2006, h_v, d_BH and trace water depth were investigated for trees which were broken or bent down by the flood. Loading test was conducted for deriving critical breaking moment of the tree trunk. Critical breaking moment of the two tree species were expressed by the function of d_BH,³ The critical breaking moment of Robinia pseudoacacia is lower than that of Salix subfragilis when the diameter is the same. Drag and drag moment acting on trees were calculated with different tree age and magnitude of flood disturbance. Return period of floods (T₂) was compared with the maximum tree age (T₁) at which tree is broken under critical breaking moment. Comparing T₁ with T₂ has the possibility to become an effective method for evaluating whether the habitat in a river has a tendency to be a forest or not.
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.11532/river.13.0_177
  DOI ID：10.11532/river.13.0_177, eISSN：2436-6714
• Change of Threshold velocity for gravel movement by runner expansion and growth of Phragmites japonica on a gravel bar : modeling approach　　　　　　　　　　　　　　　
  Tanaka, N; Yagisawa, J; Ogawa, T
  J, of Hydroscience and Hydraulic Eng., 巻：25, 号：1, 開始ページ：1, 終了ページ：10, 2007年
• 洪水攪乱影響の違いがツルヨシの形態的特徴と繁茂量・拡大幅に与える影響　　　　　　　　　　　　　　　
  青木信哉; 田中規夫; 八木澤順治
  水工学論文集, 巻：51, 号：1, 開始ページ：1255, 終了ページ：1260, 2007年
  he effect of flood disturbance on the morphology of runners, plant productivity and runner-expansion characteristics of Pharagmites japonica was investigated at midstream of the Arakawa River. The dynamic growth model of P. japonica was developed considering the effect of disturbance, i. e., the difference of runner morphology and shoot productivity in the parent colony. The aboveground biomass distribution along the distance from the parent colony was well represented by the model. For analyzing the effect of flood disturbance interval, maximum water levels at three flood events were calculated and evaluated whether the habitat of P. japonica were inundated or not. In addition, the threshold friction velocity of the average grain diameter was compared with the friction velocity at the flood event. Although the gravel movement possibility has a little different tendency with the damaged situation of P. japonica, the clear relationship between the flood interval and the productivity in each habitat is found. The analysis indicates the possibility to calculate the plant productivity under the effect of flood disturbance.
  Japan Society of Civil Engineers, 英語
  DOI：https://doi.org/10.2208/prohe.51.1255
  DOI ID：10.2208/prohe.51.1255, ISSN：0912-2508, CiNii Articles ID：10021137809, CiNii Books ID：AA1045915X
• シナダレスズメガヤの繁茂量の違いを考慮した土砂移動限界の変化および洪水時流失条件の評価　　　　　　　　　　　　　　　
  八木澤順治; 田中規夫
  水工学論文集, 巻：51, 開始ページ：1249, 終了ページ：1254, 2007年
  Field observation was conducted to elucidate the effect of Eragrostis curvula on the threshold of gravel movement at midstream of the Arakawa River. Under various hydraulic conditions (particle diameter, bed slope and water depth) and growth conditions (colony diameter and density of the plant), Shields parameter of the gravel in the plant-vegetated area was estimated using the drag characteristics of the plant and calculated friction velocity affected by the plant. Threshold of gravel movement of median grain size (d₅₀) and d₈₄ (84% of the grain weight) around the plants was evaluated by comparing friction velocity of the flow condition with the critical friction velocity of the diameter. The removal threshold of Eragrostis curvula was defined at which the friction velocity affected by the plant's drag is equal to the critical friction velocity of d₈₄. The threshold condition related to HI (H: water depth, I: bed slope) and the drag by plant was validated for a flood in the Arakawa River and for two floods in the Yoshino River.
  Japan Society of Civil Engineers
  DOI：https://doi.org/10.2208/prohe.51.1249
  DOI ID：10.2208/prohe.51.1249, ISSN：0916-7374, eISSN：1884-9172, CiNii Articles ID：130003842392
• 河道内樹木の洪水撹乱規模と樹齢による破壊限界変化　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治; 青木信哉; 福岡捷二
  巻：13, 開始ページ：177, 終了ページ：182, 2007年
• Change of Threshold velocity for gravel movement by runner expansion and growth of Phragmites japonica on a gravel bar : modeling approach　　　　　　　　　　　　　　　
  Tanaka, N; Yagisawa, J; Ogawa, T
  巻：25, 号：1, 開始ページ：1, 終了ページ：10, 2007年
• 洪水攪乱影響の違いがツルヨシの形態的特徴と繁茂量・拡大幅に与える影響　　　　　　　　　　　　　　　
  青木 信哉; 田中 規夫; 八木澤 順治
  水工学論文集, 巻：51, 開始ページ：1255, 終了ページ：1260, 2007年
  he effect of flood disturbance on the morphology of runners, plant productivity and runner-expansion characteristics of Pharagmites japonica was investigated at midstream of the Arakawa River. The dynamic growth model of P. japonica was developed considering the effect of disturbance, i. e., the difference of runner morphology and shoot productivity in the parent colony. The aboveground biomass distribution along the distance from the parent colony was well represented by the model. For analyzing the effect of flood disturbance interval, maximum water levels at three flood events were calculated and evaluated whether the habitat of P. japonica were inundated or not. In addition, the threshold friction velocity of the average grain diameter was compared with the friction velocity at the flood event. Although the gravel movement possibility has a little different tendency with the damaged situation of P. japonica, the clear relationship between the flood interval and the productivity in each habitat is found. The analysis indicates the possibility to calculate the plant productivity under the effect of flood disturbance.
  公益社団法人 土木学会
  DOI：https://doi.org/10.2208/prohe.51.1255
  DOI ID：10.2208/prohe.51.1255, ISSN：0916-7374, eISSN：1884-9172, CiNii Articles ID：10021137809, CiNii Books ID：AA1045915X
• シナダレスズメガヤの繁茂量の違いを考慮した土砂移動限界の変化および洪水時流失条件の評価　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫
  水工学論文集, 巻：51, 開始ページ：1249, 終了ページ：1254, 2007年
  Field observation was conducted to elucidate the effect of Eragrostis curvula on the threshold of gravel movement at midstream of the Arakawa River. Under various hydraulic conditions (particle diameter, bed slope and water depth) and growth conditions (colony diameter and density of the plant), Shields parameter of the gravel in the plant-vegetated area was estimated using the drag characteristics of the plant and calculated friction velocity affected by the plant. Threshold of gravel movement of median grain size (d₅₀) and d₈₄ (84% of the grain weight) around the plants was evaluated by comparing friction velocity of the flow condition with the critical friction velocity of the diameter. The removal threshold of Eragrostis curvula was defined at which the friction velocity affected by the plant's drag is equal to the critical friction velocity of d₈₄. The threshold condition related to HI (H: water depth, I: bed slope) and the drag by plant was validated for a flood in the Arakawa River and for two floods in the Yoshino River.
  Japan Society of Civil Engineers
  DOI：https://doi.org/10.2208/prohe.51.1249
  DOI ID：10.2208/prohe.51.1249, ISSN：0916-7374, CiNii Articles ID：130003842392
• スリランカ南部海岸線におけるインド洋大津波被害実態調査(その２) : 海岸林の破壊限界モーメントに注目して<論文>　　　　　　　　　　　　　　　
  田中 規夫; 佐々木 寧; MOWJOOD M.I.M.; JINADASA K.B.S.N.; 八木澤 順治
  埼玉大学紀要. 工学部 第1編 第1部 論文集, 巻：39, 開始ページ：58, 終了ページ：65, 2006年07月
  This study explored the effects of coastal vegetation and sand dune on tsunami protection based on field observations carried out in two periods after the Indian Ocean tsunami. First one was conducted for elucidating the relationship between the representative species and the damage, from 1 to 6 April 2005 in Sri Lanka. The second survey was conducted for investigating the breaking condition of the representative trees, from 5 to 9 January, 2006 at Kalutra, Medilla, Rekawa and Hambantota where the combination of the sand dune followed by vegetation towards landside played an important role. The breaking moment of trees were investigated for the representative trees by pulling test. The threshold value for breaking condition was derived as a function of trunk diameter. The breaking moment equation represents well in the limitation of the representative species with the tsunami height at the tsunami event considering the aerial root height. These findings have to be considered in future coastal landscape planning and tsunami hazard mapping.
  埼玉大学工学部, 日本語
  DOI：https://doi.org/10.24561/00016113
  DOI ID：10.24561/00016113, ISSN：1880-4446, CiNii Articles ID：120001370425
• 砂礫河原に繁茂する株状草本シナダレスズメガヤの土砂捕捉特性と洪水攪乱による除去条件　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治; 青木信哉
  河川技術論文集, 巻：12, 開始ページ：455, 終了ページ：460, 2006年
• ツルヨシのランナーによる群落拡大が土砂の移動限界に与える影響　　　　　　　　　　　　　　　
  八木澤順治; 田中規夫; 青木信哉
  水工学論文集, 巻：50, 開始ページ：1177, 終了ページ：1182, 2006年
  DOI：https://doi.org/10.2208/prohe.50.1177
  DOI ID：10.2208/prohe.50.1177
• 砂礫河原に繁茂する株状草本シナダレスズメガヤの土砂捕捉特性と洪水攪乱による除去条件　　　　　　　　　　　　　　　
  田中規夫; 八木澤順治; 青木信哉
  巻：12, 開始ページ：455, 終了ページ：460, 2006年
• ツルヨシのランナーによる群落拡大が土砂の移動限界に与える影響　　　　　　　　　　　　　　　
  八木澤 順治; 田中 規夫; 青木 信哉
  水工学論文集, 巻：50, 開始ページ：1177, 終了ページ：1182, 2006年
  The effect of the enlargement of Phragmites japonica on the threshold of gravel movement was investigated by field observation at midstream of the Arakawa River. The lateral biomass distribution was simulated by the growth dynamic model of P. japonica including their shoot characteristics. The extended width by runner system was about 30 m, almost coincided with the width of the 3 year's plant stand in field. The effect of the plant enlargement on the threshold of gravel movement as evaluated by the lateral distribution of the drag force in relation to the plant biomass. The analysis indicated that the area lower than the threshold of gravel movement becomes exponentially large after 3-5 years with no disturbance even if the initial colonization is scattered.
  公益社団法人 土木学会
  DOI：https://doi.org/10.2208/prohe.50.1177
  DOI ID：10.2208/prohe.50.1177, ISSN：0916-7374, eISSN：1884-9172, CiNii Articles ID：130004043767
• 飛沫通過量を最小にする最適防風フェンス構造に関する風洞実験<論文>　　　　　　　　　　　　　　　
  田中 規夫; 高木 利光; 山崎 典和; 児玉 敏雄; 八木澤 順治
  埼玉大学紀要. 工学部 第1編 第1部 論文集 = The Science and Engineering Reports of Saitama University, 巻：39, 開始ページ：66, 終了ページ：73, 2006年
  type:text
  For decreasing the spray flux by wave-breaking at the shoreline to the landward area, the optimal wind protection fence structure was discussed. For minimizing the salt-spray flux through the fence, the structure with two low circular or L-shaped cylinders in staggered grid arrangement was selected and wind tunnel experiments were conducted with different spacing for cross-stream and stream-wise direction. The salt spray amount settling at the fence and passing through the fence were measured. The spray volume getting through or blowing up the fence was quantified by colored water with dye. The water was sprayed with a sprayer and collected by gauzes setting at downstream points. For the subsidence volume at the bottom in downstream, a tray was put and the mass of the subsiding water was measured. Considering the loss by blowing upward of the fence, the appropriate arrangement was found as `the two rows of circular cylinders with staggered, 1D cross-stream spacing and 1D-2D stream-wise length, where D is the diameter of a circular cylinder’. This amount of the subsidence is about 90% and more than the value of previous-existed fence structure, 70%.
  埼玉大学工学部, 日本語
  DOI：https://doi.org/10.24561/00016114
  DOI ID：10.24561/00016114, ISSN：1880-4446, CiNii Articles ID：120006387948
• 大型湿地植生の洪水によるダメージと回復過程を考慮した適正洪水導入規模に関する研究<論文>　　　　　　　　　　　　　　　
  田中 規夫; Das S.C.; 武村 武; 八木澤 順治
  埼玉大学紀要. 工学部 第1編 第1部 論文集, 巻：38, 開始ページ：58, 終了ページ：65, 2005年03月
  Field experiment was conducted for elucidating the damage effect on the productivity of wetland species, Phragmites australis, and upland species, Miscanthus sacchariflorus, in a river-floodplain. River flow was analyzed by two-dimensional depth-averaged Reynolds equation to solve the moment acting on the stems. Regrowth dynamic model considering their stem-breaking was formulated and their growth was analyzed in relation to flood discharge, flood interval and their stem-breaking moment. If their stem breaking is occurred every year, survival of the two species is difficult. However, they can survive with 2-5 years' interval and the superiority of M. sacchariflorus is decreased with stem-breaking condition. However, the breaking moment of M. sacchariflorus was larger than that of P. australis and the decrement in belowground biomass was smaller under bending damage. This indicates that the weak flood does not change their competitive superiority.
  埼玉大学工学部, 日本語
  DOI：https://doi.org/10.24561/00016079
  DOI ID：10.24561/00016079, ISSN：1880-4446, CiNii Articles ID：120001370748
• 抽水植物ヒメガマ・マコモの地上部刈り取りに対する地下部動態と戦略　　　　　　　　　　　　　　　
  渡辺 哲広; 田中 規夫; 武村 武; 八木澤 順治; 浅枝 隆
  水工学論文集, 巻：48, 開始ページ：1603, 終了ページ：1608, 2004年
  Typha angustifolia were cut in June, July and August in 2002, and in May and July in 2003 for i nvestigating their strategy to survive from cutting at different timing. Zizania latifolia was also cut in July in 2003. The cutting effects were evaluated quantitatively by regrowth characteristics of aboveground leaves just after cutting. The belowground production of T. angustifolia was decreased by summer cutting. This was due to the decrement of transportation from original shoot to belowground and from regrowth shoot to belowground organ. July to August is the best season for controlling expansion of the species, because the transportation can be decreased by the cutting. The amount of transportation from belowground to aboveground organ was a little compared with the decrement of belowground biomass and was almost the same with the two species, but heterotrophic season just after cutting were found 15 days, 40days in case of T. angustifolia and Z. latifolia, respectively. The season was longer and secondary shoot was formed in case of Z. latifolia. This implies the different strategy of Z. latifolia with T. angustifolia.
  公益社団法人 土木学会
  DOI：https://doi.org/10.2208/prohe.48.1603
  DOI ID：10.2208/prohe.48.1603, ISSN：0916-7374, eISSN：1884-9172, CiNii Articles ID：130004043578

• 落葉層が降雨時の火山灰流出量に及ぼす影響に関する実験的研究　　　　　　　　　　　　　　　
  桑原哲也; 八木澤 順治
  土木学会関東支部第52回学術研究発表会, 2025年03月
  2025年03月 - 2025年03月, 日本語, 口頭発表（一般）
• Flow structures and sedimentation characteristics around colony-type vegetation at flood events　　　　　　　　　　　　　　　
  16th Congress of Asia and Pacific Division of International Association of Hydraulic Engineering and Research and 3rd IAHR International Symposium on Hydraulic Structures, 2008年
• Evaluation of removal condition of invasive plant ‘Eragrostis curvula’ by considering erosion rate　　　　　　　　　　　　　　　
  ICHE(The 8th International Conference on Hydro-Science and engineering), 2008年
• 株状粗度群内の底面せん断力特性の評価に関する実験的研究　　　　　　　　　　　　　　　
  土木学会第63回年次講演会, 2008年
• 側岸侵食が樹木の流失限界に及ぼす影響　　　　　　　　　　　　　　　
  土木学会第63回年次講演会, 2008年
• Differences of Tree-breaking Pattern and Breaking Moment by Floods with Different Tree Age and Substrate Condition under Two Flood Disturbances　　　　　　　　　　　　　　　
  ICHE, 2008年
• Flow structures and sedimentation characteristics around colony-type vegetation at flood events　　　　　　　　　　　　　　　
  16th Congress of Asia and Pacific Division of International Association of Hydraulic Engineering and Research and 3rd IAHR International Symposium on Hydraulic Structures, 2008年
• Evaluation of removal condition of invasive plant ‘Eragrostis curvula’ by considering erosion rate　　　　　　　　　　　　　　　
  ICHE(The 8th International Conference on Hydro-Science and engineering), 2008年
• 株状粗度群内の底面せん断力特性の評価に関する実験的研究　　　　　　　　　　　　　　　
  土木学会第63回年次講演会, 2008年
• 側岸侵食が樹木の流失限界に及ぼす影響　　　　　　　　　　　　　　　
  土木学会第63回年次講演会, 2008年
• Differences of Tree-breaking Pattern and Breaking Moment by Floods with Different Tree Age and Substrate Condition under Two Flood Disturbances　　　　　　　　　　　　　　　
  ICHE, 2008年
• 樹木群模型周辺の流れ構造と繁茂状態の異なる実樹木群周辺の土砂堆積特性　　　　　　　　　　　　　　　
  土木学会第62回年次講演会, 2007年
• 河道内樹木の鉛直構造の違いを考慮した合成抗力作用高さの変化　　　　　　　　　　　　　　　
  土木学会第62回年次講演会, 2007年
• 樹木群模型周辺の流れ構造と繁茂状態の異なる実樹木群周辺の土砂堆積特性　　　　　　　　　　　　　　　
  土木学会第62回年次講演会, 2007年
• 河道内樹木の鉛直構造の違いを考慮した合成抗力作用高さの変化　　　　　　　　　　　　　　　
  土木学会第62回年次講演会, 2007年
• シナダレスズメガヤ周辺の土砂移動限界の変化および同植物の洪水時除去条件　　　　　　　　　　　　　　　
  応用生態工学研究会第10回大会, 2006年
• Plant expansion modeling for analyzing the change of the threshold velocity of gravel movement　　　　　　　　　　　　　　　
  ICEM2006, 2006年
• Effects of flood interval on the growth of Phragmites japonica and the change of threshold velocity for gravel movement　　　　　　　　　　　　　　　
  15th APD-IAHR Congress, 2006年
• シナダレスズメガヤ周辺の土砂移動限界の変化および同植物の洪水時除去条件　　　　　　　　　　　　　　　
  応用生態工学研究会第10回大会, 2006年
• Plant expansion modeling for analyzing the change of the threshold velocity of gravel movement　　　　　　　　　　　　　　　
  ICEM2006, 2006年
• Effects of flood interval on the growth of Phragmites japonica and the change of threshold velocity for gravel movement　　　　　　　　　　　　　　　
  15th APD-IAHR Congress, 2006年
• 洪水攪乱により土砂被りを受けたツルヨシの翌年の再生長特性　　　　　　　　　　　　　　　
  応用生態工学研究会第9回大会, 2005年
• 礫河原における多年生草本シナダレスズメガヤ(Eragrostis curvula)の除去条件の評価　　　　　　　　　　　　　　　
  応用生態工学研究会第9回大会, 2005年
• 洪水攪乱により土砂被りを受けたツルヨシの翌年の再生長特性　　　　　　　　　　　　　　　
  応用生態工学研究会第9回大会, 2005年
• 礫河原における多年生草本シナダレスズメガヤ(Eragrostis curvula)の除去条件の評価　　　　　　　　　　　　　　　
  応用生態工学研究会第9回大会, 2005年

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• 2024, 博士前期(専門職学位)課程, 指導学生数計：4, 指導学生数(内留学生)：1

• 土木学会

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  競争的資金
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  競争的資金