Directory of Researchers
| NAKAYAMA Keisuke |  |
| Graduate School of Engineering / Department of Civil Engineering | |
| Professor | |
| Civil Engineering / Architecutre and planning / Building Engineering |
Researcher Profile and Settings
Affiliation
＜Faculty / Graduate School / Others＞
Graduate School of Engineering / Department of Civil Engineering＜Related Faculty / Graduate School / Others＞
Faculty of Engineering / Department of Civil Engineering
Teaching
- Graduate School of Engineering / Department of Civil Engineering, 2021, Environmental Limnology
- Graduate School of Engineering / Department of Civil Engineering, 2021, Limnological Environment
- Faculty of Engineering / Department of Civil Engineering, 2021, Environmental Limnology
- Faculty of Engineering / Department of Civil Engineering, 2021, Seminar for Creative Thinking I-a
- Faculty of Engineering / Department of Civil Engineering, 2021, Environmental Limnology
- Faculty of Engineering / Department of Civil Engineering, 2021, Seminar for Creative Thinking I-b
- Faculty of Engineering / Department of Civil Engineering, 2021, Civil Engineering Practice
- Faculty of Engineering / Department of Civil Engineering, 2021, Water Supply Engineering
- Faculty of Engineering / Department of Civil Engineering, 2021, Hydraulics and Practice
- Faculty of Engineering / Department of Civil Engineering, 2021, Hydraulics
- Faculty of Engineering / Department of Civil Engineering, 2021, Sewerage Engineering
- Faculty of Engineering, 2021, Introduction to English Communication for Engineering
- Faculty of Engineering, 2021, Advanced Liberal Arts Seminar in Faculty of Engineering (Civil Engineering)
Research Activities
Research Interests
Research Areas
Committee Memberships
- Jun. 2019 - Present, 土木学会, 気候変動適応研究推進小委員会 委員長
- Apr. 2019 - Present, 環境省, 気候変動適応近畿広域協議会委員
- 2019 - Present, 国土交通省, 温暖化適応策創生・実装連携会委員
- Apr. 2018 - Present, 島根大学, 島根大学研究推進協議会委員
- Apr. 2017 - Mar. 2019, 環境省, 地域適応コンソーシアム近畿委員
- Apr. 2016 - Present, 国土交通省, 河川懇談会委員
- Apr. 2016 - Mar. 2018, 大阪府, 「豊かな大阪湾」創出手法に関する懇話会委員
- Jun. 2015 - Present, 土木学会水工学委員会 委員
- Jun. 2015 - May 2017, 土木学会, 水工学委員会 幹事長
- Jun. 2013 - May 2018, 土木学会, 海岸工学委員会 幹事
- Jun. 2013 - May 2018, 土木学会, 海岸工学委員会 波動小委員会 副小委員長
- Apr. 2013 - Present, マリモ科学委員会 委員
- Apr. 2008 - Present, 国土交通省, 釧路湿原水循環小委員会 委員
Awards
2010 北海道開発協会長賞
2006 Award on the United Nations Atlas Book
2005 Gledden Senior Fellowship Award
1998 平成9年度水工学論文奨励賞
1998 平成10年度水文水資源学会ポスター賞
1995 平成7年度土木学会年次学術講演会優秀講演者賞
1992 吉町先生記念賞
1992 廣井勇記念賞
Published Papers
- Aug. 2021, Physics of Fluids
Scientific journal
- Elsevier {BV}, Jun. 2021, Ocean Engineering, 230, 108884 - 108884
Scientific journal
- Informa {UK} Limited, 24 Apr. 2021, Coastal Engineering Journal, 1 - 14
Scientific journal
- American Geophysical Union ({AGU}), 18 Apr. 2021, Journal of Geophysical Research: Biogeosciences
Scientific journal
In present study, the effect of the seasonal difference in photosynthetic activity of eelgrass on the absorption/release characteristics of dissolved inorganic carbon was clarified from the results of model analysis of changes in dissolved inorganic carbon by aquatic tank experiments using eelgrass and chlorophyll-a content analysis. It was revealed that the optimum value of the maximum photosynthetic rate for dissolved inorganic carbon by eelgrass varies depending on the season of the experiment. From the estimated values by the model and the results of the chlorophyll-a content of eelgrass, it was suggested that the difference in the growth stage of eelgrass affected the photosynthetic activity and the maximum photosynthetic rate. The results obtained based on the measured values of the detailed specifications of eelgrass were applied to the model to clarify the relationship between the characteristics of the vertical profile of dissolved inorganic carbon and the branching structure of eelgrass.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 77 (2), I_565 - I_570, JapaneseThis study investigated the effect of eelgrass respiration and photosynthesis on DIC's horizontal distribution at Lake Komuke in northeastern Hokkaido using a newly extended SAV model (Submerged Aquatic vegetation model). The original SAV model successfully predicts the interaction between fluid and vegetation, however it needs enormous computational resources for field scale simulations. Therefore, the Super SAV model, which integrates a few hundred SAVs into only one SAV, was proposed in this study. The Super SAV model was validated by comparing the velocity field and diffusion coefficient with the original SAV model under a current uniform condition. The Super SAV model, which considers respiration and photosynthesis by eelgrass, was incorporated into a three-dimensional hydrodynamic model. The results obtained by the Super SAV model was demonstrated to agree with the observed data in Lake Komuke.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 77 (2), I_613 - I_618, Japanese- 25 Nov. 2020, Journal of Fluid Mechanics
[Refereed]
Scientific journal
- American Geophysical Union ({AGU}), 29 Oct. 2020, Journal of Geophysical Research: Oceans, 125 (10)
[Refereed]
Scientific journal
- Sep. 2020, Proc. 22nd Int. Conf. on IAHR-APD, 1 - 6EVALUATION OF HYDRODYNAMIC EFFECTS ON BLUE CARBON DYNAMICS IN THE YATSUSHIRO SEA
[Refereed]
- Sep. 2020, Proc. 22nd Int. Conf. on IAHR-APD, 1 - 6FIELD OBSERVATION ON BLUE CARBON DYNAMICS IN THE YATSUSHIRO SEA CONSIDERING INFLUENCE OF STRATIFICATION
[Refereed]
- Sep. 2020, Proc. 22nd Int. Conf. on IAHR-APD, 1 - 6APPLICATION OF OPTICAL FLOW TECHNIQUES FOR RIVER SURFACE FLOW MEASUREMENTS
[Refereed]
- Sep. 2020, Proc. 22nd Int. Conf. on IAHR-APD, 1 - 6DISCHARGE ESTIMATION BY STIV COMBINED WITH THE MAXIMUM ENTROPY METHOD
[Refereed]
- American Geophysical Union ({AGU}), 03 Aug. 2020, Water Resources Research, 56 (8)
[Refereed]
Scientific journal
- Jul. 2020, International Journal of Environmental Science and Development, 11 (7), 352 - 357, EnglishEmpirical Approach for Modeling of Partition Coefficient on Lead Concentrations in Riverine Sediment
[Refereed]
Scientific journal
- Elsevier {BV}, 2020, Ecological Modelling, 431, 109188 - 109188
[Refereed]
Scientific journal
- Elsevier {BV}, 2020, Science of the Total Environment, 717, 137052 - 137052
[Refereed]
Scientific journal
In Kushiro River basin, inundation is likely to occur due to heavy rain, since the river-bed slope is very gentle in the downstream portion, which has natural levees. Consequently, in past floods, river discharge was observed to increase slowly and a delay of a few days in peak river discharge was observed compared to the peak precipitation. Therefore, we applied a distributed hydrological model, Geophysical fluid CIRCulation model (GeoCIRC), to reproduce such flood discharge in Kushiro River. GeoCIRC is based on object-oriented programming and various hydrological processes, such as infiltration flow, underground water flow, surface flow, and river flow can be implemented easily. We proposed a model that can incorporate the effect of return flow using storage function by introducing new parameters, such as storage time and time lag. This was done to consider not only the flood inundation in Kushiro River but also the return flow from flood inundation to the river flow. As a result, we obtained high Nash-Sutcliffe coefficients for river discharge for two large flood events.
Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH), 2020, Hydrological Research Letters, 14 (2), 75 - 80, English[Refereed]
Scientific journal
This study aims to develop a new wave equation model by modifying the Fully-nonlinear and strongly-Dispersive Surface wave (FDS) equations. The modification was performed by applying a new expansion in a series of the vertical coordinate, z(mu), to the velocity potential while a simple expansion in a series of z was applied to the FDS equations. Verification of the model was conducted by comparing with the theoretical solutions of surface solitary waves. We applied the modified FDS equations to wave fields over a bump under conditions with and without currents, which agreed very well with the time series of wave heights and velocity obtained from laboratory experiments. The dispersion relationship computed using the normalized modified FDS equations also agreed very well with the theoretical solution when we gave the number of expansion terms as 3 with mu = 2.5. Additionally, the profile of surface waves computed with the modified FDS equation was shown to have a larger width ridge, a bulbous-type wave, by comparing with a Trochoidal wave under the condition of waves against a current.
Informa {UK} Limited, 2020, Coastal Engineering Journal, 62 (2), 159 - 169, English[Refereed]
Scientific journal
In order to reveal the carbon uptake mechanism of eelgrass, the vertical distribution of dissolved inorganic carbon (DIC) was estimated by a conceptual model considering the stratification effect at Lake Komuke. The field observation show that the eelgrass meadows change stratification and the vertical distribution of DIC. The conceptual model was verified by comparing with the vertical diffusion coefficients obtained from the Submerged Aquatic Vegetation model (SAV model). As a result, the conceptual model results agreed with the SAV model when eelgrass exists densely in a strong stratified fluid. Additionally, SAV model was improved in order to reduce run-time cost by combining with a hydrostatic model. The improved SAV model shows high accuracy and the run time was reduced dramatically.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 76 (2), I_869 - I_874, Japanese"Blue carbon", which is carbon fixed by marine organisms, is attracting attention as a new measure to reduce atmospheric CO2. We carried out field survey regarding the CO2 partial pressure (pCO2) in sea water in the Yatsushiro Sea where it is confirmed that habitats of corals and seagrass, in order to reveal the pCO2 dynamics in actual situation. Moreover, by observation under different mixing conditions, we tried to reveal how stratification can affect on the dynamics. As a result, it was confirmed that with the development of strong stratification, the effect of photosynthesis by phytoplankton was concentrated on the surface and pCO2 decreased. In addition, it was suggested that the influx of water affected by corals caused the fluctuation of pCO2. Finally, trial calculation of CO2 flux between sea and air in daytime shows that the Yatshiro Sea can absorb CO2 throughout the year, regardless of the mixing conditions.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 76 (2), I_901 - I_906, Japanese- 土木学会, Nov. 2019, 水工学論文集 Annual journal of Hydraulic Engineering, JSCE, 64, I_769 - 774, JapaneseCLASSIFICATION OF INTERNAL WAVE BREAKING OVER A SLOPE WITH THE CHANGE IN THE THICKNESS OF PYCNOCLINE
[Refereed]
- 土木学会, Nov. 2019, 水工学論文集 Annual journal of Hydraulic Engineering, JSCE, 64, I_445 - 450, JapaneseRESONANT CHARACTERISTICS OF TRIANGULAR WAVE SEQUENCE OVER SHALLOW FLOW WITH SPARSELY DISTRIBUTED STRIP ROUGHNESS
[Refereed]
- Nov. 2019, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 75 (2), I_775 - I_780, JapaneseESTIMATION OF ROTATION ANGLE AND CRITICAL VELOCITY OF MARIMOS DUE TO WAVES AND CURRENTS
[Refereed]
Scientific journal
- MEASUREMENT OF SEAGRASS DISTRIBUTION BY SATELLITE DATA AND VARIDATION USING DISSOLVED INORGANIC CARBON IN LAGOON
Seagrass distribution in a lagoon located near the Sea of Okhotsk was estimated from satellite data, and varidated using DIC and its variation obtained by field observation data. Seagrass distribution was made by converted data from averaged NDVI of satellite Sentinel-2 to seagrass vegetation density. As a result of calculation of DIC model, since field observation data at 17 points in/out of seagrass vegetation area for a period of from July to August in 2018 were successfully represented, seagrass distribution using satellite NDVI was well verified. Bias of calculation results were appeared due to seagrass existence, however, the estimation insufficiency of vegetation under the water and the influence of hydraulic re-sistance of seagrass to tidal current and water quality were likely associated.
Nov. 2019, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 75 (2), I_397 - I_402, Japanese[Refereed]
Scientific journal
- Japan Society of Civil Engineers, Oct. 2019, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 75 (2), I_25 - 30, Japanese
[Refereed]
- The International Association for Hydro-Environment Engineering and Research (IAHR), 01 Sep. 2019, 38th IAHR World Congress - "Water: Connecting the World"
International conference proceedings
- Sep. 2019, Proc. 10th Int. Conf. on Asian and Pacific Coasts, 10, EnglishResidence time in a lagoon system
[Refereed]
Scientific journal
We developed the hydrodynamic model of Yatsushiro Sea in order to analyze stratified flow field and water quality in Yatsushiro Sea. Yatsushiro Sea is connected to Ariake Sea with very narrow strait, which cannot be modelled due to the limitation of computational capacity. Therefore, we made an attempt to develop the SYA (Strait between Yatsushiro Sea and Ariake Sea) model to estimate fluxes of seawater exchange through SYA. It was found that there is no seasonal difference in seawater exchange flux. As a result, field observations were successfully reproduced by applying the SYA model into the Yatsushiro Sea model with good agreements.
Japan Society of Civil Engineers, Jul. 2019, 土木学会論文集B3（海洋開発）, 75 (2), I_977 - I_982, Japanese[Refereed]
Scientific journal
- Jul. 2019, 土木学会論文集B3（海洋開発）, 75 (2), I_504 - I_509, Japanese水深葉長比を考慮した有効水草高さに関する検討
[Refereed]
Scientific journal
- 2019, Physical Review Fluids, 4 (1), 014801, English
[Refereed]
Scientific journal
- 2019, European Journal of Mechanics, B/Fluids, 74, 81 - 91, English
[Refereed]
Scientific journal
- 2019, PLoS ONE, 14 (12), English
[Refereed]
Scientific journal
- 2019, Water Science and Technology, 80 (1), 11 - 24, English
[Refereed]
Scientific journal
- Dec. 2018, 土木学会論文集B1（水工学）, 74 (5), I - 535-I_540, Japanese貯水池底層における貧酸素水塊発生機構の解明
[Refereed]
Scientific journal
- Dec. 2018, 土木学会論文集B1（水工学）, 74 (5), I - 1513-I_1518, Japanese浅水流方程式・局所慣性方程式の精度検証と最適空間解像度に関する検討
[Refereed]
Scientific journal
- Dec. 2018, 土木学会論文集B1（水工学）, 74 (5), I - 1459-I_1464, Japanese洪水氾濫シミュレーションにおいて風の影響を考慮する必要性に関する検討
[Refereed]
Scientific journal
- Dec. 2018, 土木学会論文集B1（水工学）, 74 (5), I - 517-I_522, Japanese個別要素法を環境流体解析に組み込んだマリモモデルの開発
[Refereed]
Scientific journal
- Nov. 2018, 土木学会論文集B2（海岸工学）, 74 (2), I_31 - I_36, Japanese波・流れ場とアマモ場の相互干渉解析
[Refereed]
Scientific journal
- Nov. 2018, 土木学会論文集B2（海岸工学）, 74 (2), I_655 - I_660, Japanese二層システムにおける内部ソリトン波の斜面上での砕波形態と物質輸送
[Refereed]
Scientific journal
- Nov. 2018, 土木学会論文集B2（海岸工学）, 74 (2), I_25 - I_30, Japanese水深が変化する水域を伝播する内部波の数値解析
[Refereed]
Scientific journal
- Nov. 2018, 土木学会論文集B2（海岸工学）, 74 (2), I_1 - I_6, Japanese強非線形強分散波動方程式の改良とbumpを有する波動場への適用
[Refereed]
Scientific journal
- Nov. 2018, 土木学会論文集B2（海岸工学）, 74 (2), I_1237 - I_1242, Englishアマモ場における海水中CO2分圧モデルの開発
[Refereed]
Scientific journal
- Jul. 2018, 土木学会論文集B3（海洋開発）, 74 (2), I_444 - I_449, Japanese成層を考慮したアマモ場における溶存無機炭素の変動解析
[Refereed]
Scientific journal
- Mar. 2018, 土木学会論文集B1（水工学）, 74 (4), I - 355-I_360, Japanese千刈貯水池を対象とした出水時の成層場に関する検討
[Refereed]
Scientific journal
- Mar. 2018, 土木学会論文集B1（水工学）, 74 (4), I - 1423-I_1428, Japanese解析解を利用した準長波方程式による洪水氾濫解析
[Refereed]
Scientific journal
- Mar. 2018, 土木学会論文集B1（水工学）, 74 (4), I - 505-I_510, Japaneseイオンクロマトグラフィーを利用したBayesian理論による溶存物質の輸送割合推定手法の開発
[Refereed]
Scientific journal
- ESTIMATION OF DISSOLVED SUBSTANCES TRANSPORT IN KUSHIRO RIVER BASIN USING DISSOLVED ION PATTERN
Large amount of nutrient salt and dissolved organic matter is transported from Kushiro River basin to coastal area. In present paper, seasonality of transport ratio in dissolved inorganic matter from upstream catchment to downstream reach was estimated by using multiple regression mothod incorporating Bayesian theory into major ion pattern in stream water. Transport ratios could be well verified and esti-mated in several percent of errors. Seasonality of contribution ratio was clearly observed in comparison with uncertain errors. Ion representing each catchment should be extracted in advance by using statistical test.
土木学会, 2018, Annual journal of Hydraulic Engineering, JSCE, 62, I_505 - I_510, Japanese[Refereed]
Scientific journal
- 2018, Estuarine, Coastal and Shelf Science, 212, 286 - 293, English
[Refereed]
Scientific journal
- Nov. 2017, 土木学会論文集B2（海岸工学）, 73 (2), I_31 - I_36, Japanese斜面上における内部ソリトン波の砕波形態の分類
[Refereed]
Scientific journal
- Nov. 2017, 土木学会論文集B2（海岸工学）, 73 (2), I_55 - I_60, Japanese3層系における内部波列による質量輸送速度
[Refereed]
Scientific journal
- Jun. 2017, 土木学会論文集B3（海洋開発）, 73 (2), I_821 - I_826, Japanese波・流れ場とアマモの連成モデルの構築
[Refereed]
Scientific journal
- Jun. 2017, 土木学会論文集B3（海洋開発）, 73 (2), I_618 - I_623, JapaneseRoberts Bank tidal flatにおける干潟内流動と塩分濃度
[Refereed]
Scientific journal
- Mar. 2017, 土木学会論文集B1（水工学）, 73 (4), I - 979-I_984, Japanese貯水池における出水時の成層場鉛直混合に関する検討
[Refereed]
Scientific journal
- Mar. 2017, 土木学会論文集B1（水工学）, 73 (4), I_1405 - I_1410, Japanese洪水氾濫解析を対象とした浅水流方程式の適用性に関する検討
[Refereed]
Scientific journal
- Mar. 2017, 土木学会論文集B1（水工学）, 73 (4), I - 1177-I_1182, Japanese蛍光X線分析を利用した細粒土砂の輸送割合と安定同位体比による窒素循環量の推定
[Refereed]
Scientific journal
- Mar. 2017, Annual Journal of Hydraulic Engineering, JSCE, 73 (4), I_1159 - I_1164, EnglishHeavy metals transport simulation by physically based distributed modeling approach (case of study: Harrash River, Algeria)
[Refereed]
Scientific journal
- 2017, Journal of Geophysical Research: Oceans, 122 (9), 7449 - 7465, English
[Refereed]
Scientific journal
To investigate the diurnal changes of water CO2 fugacity in urbanized shallow waters, we performed in situ measurements throughout the day in both summer and winter in Hiragata Bay located in Yokohama. We statistically analyzed the observed data set using the structured equation modeling (SEM) and the path analysis. As a result, we found that the diurnal variation in the fugacity of CO2 was largely affected by the TA and DIC changes that are moderated mainly by urban drainage and biological metabolism.
Japan Society of Civil Engineers, 2017, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 73 (2), I_1297 - I_1302, Japanese[Refereed]
Scientific journal
アマモ場内では波・流れの影響を受けて水中の溶存物質が移流拡散しており，アマモと波・流れが相互に影響しあっていることを考慮しつつ，アマモ場内のCO2 の移流拡散を検討することは，現在に至るまで極めて困難であった．しかし，アマモの移動速度に着目し，抗力・浮力・摩擦・弾性体を考慮したアマモのモデルを作成し，波・流れ場とアマモの動きを連成することによって，アマモの形状およびアマモ場における流速を同時に再現することが出来た．アマモモデルをより高精度にするために，アマモの幅に関して１本のアマモをある高さから４本に分かれると考慮して，幅を急に変化させる場合と滑らかに変化させる場合の2種類の考え，それぞれを検証し結果を考察した．結果は，滑らかに幅を変位させたほうが良好であることが分かった．しかし，その効果は一様流において有意であり，振動流では改善効果は小さいことも分かった．
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2017, Proceeding of Annual Conference, 30, 93 - 93, Japanese分布型流出モデルを用いて流出解析を行う際，長波方程式を用いる洪水氾濫計算に最も多くの時間を要するため，一般的に現場において再現・予測計算を実施することは困難である．汎用的なPCを利用して現場において解析を容易に実施できるようにするためには，洪水氾濫計算を高速化し，計算負荷を小さくする必要がある．
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2017, Proceeding of Annual Conference, 30, 74 - 74, Japanese
そこで本研究では，長波方程式に代わるモデルとして，段波モデル，修正段波モデル，キネマティックウェーブ理論に基づくモデルの３つの簡易洪水氾濫モデルを提案し，それぞれのモデルの再現性の検証を行った．再現性の検証は長波方程式を解いた結果を厳密解として行った．再現性の評価はCoDを用いたフロントの形状，およびフロント位置の比較により行う．
検証の結果，修正段波モデルを用いた場合が最も再現性が良いことが分かった．また，修正段波モデルを用いて計算を実行するとフロント形状が滑らかになる特徴があり，数値計算上の不安定が生じにくいこともわかった．その理由として，段波の進行に対して逆方向の流速を考慮しているためであると考えることができ，この点でも修正段波モデルは優れたモデルであると言える．
計算速度は簡易洪水氾濫モデルを用いた計算の場合，厳密解を求める計算と比較して約12倍になった．つまり，実際の洪水氾濫に適用する際にも大きな時間短縮を見込むことができる．
今後は，今回良い結果が得られたモデルについて粗度の効果及び勾配の効果を考慮できるよう改良し，実際の洪水氾濫計算に適用することを試みる．沿岸域において，風や潮汐などの外力が与えられると密度界面に内部波が発生し，内部波は内部ソリトン波として安定して進行し，やがて沿岸域の斜面上などで砕波する．その際fission，plunging，collapsing，surgingの4種類の砕波形態が発生することが確認されており，その発生条件は2層システムを考えた場合の密度差，沿岸域の斜面勾配，内部ソリトン波の波高などによって決まる．さらに，過去の研究において，砕波形態が異なることで輸送フラックス等が大きく変化するため，物質輸送のされ方が異なることが示されている．そこで本研究では，物質が貯留されやすいのは密度界面であることを考慮し，砕波形態が異なるときの密度界面における物質輸送の違いを確かめた．主たる結果として，fission，plungingはcollapsing，surgingと比べて沿岸域への輸送エネルギーが大きいことが分かった．また，fission型の砕波発生時には，下層にある貧酸素水塊などの有害な物質がトラップされたコアによって沿岸域の浅い位置まで輸送されることが分かった．
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2017, Proceeding of Annual Conference, 30, 94 - 94, Japanese- Nov. 2016, 土木学会論文集B2（海岸工学）, 72 (2), I_13 - I_18, Japanese表面波・内部波共存場における孤立波解
[Refereed]
Scientific journal
- Nov. 2016, 土木学会論文集B2（海岸工学）, Japanese渦度を考慮した強非線形強分散波動方程式による解析
[Refereed]
Scientific journal
- Nov. 2016, 土木学会論文集B2（海岸工学）, 72 (2), I_7 - I_12, Japaneseソリトン波群の共鳴を対象とした強非線形強分散波動方程式による解析
[Refereed]
Scientific journal
- Jul. 2016, 土木学会論文集, 72 (1), 27 - 41, Japanese表面孤立波及び内部孤立波の特性
[Refereed]
Scientific journal
- Jun. 2016, 土木学会論文集B3（海洋開発）, 72 (2), I_1021 - I_1026, Japanese阿寒湖チュウルイ湾におけるマリモに回転運動を与える風波の将来予測に向けて
[Refereed]
Scientific journal
- Jun. 2016, 土木学会論文集B3（海洋開発）, 72 (2), I_1099 - I_1104, JapaneseRoberts Bank tidal flatにおけるbiofilm形成に重要な物理・塩分環境の要因解析
[Refereed]
Scientific journal
- Mar. 2016, Annual Journal of Hydraulic Engineering, JSCE, 72 (4), I_1039 - I_1044, EnglishSuspended sediment transport estimation by X-ray fluorescence analysis
[Refereed]
Scientific journal
Dissolved organic matter was measured by using Fluorescence Spectroscopy (FS) along with salinity from snowmelt season to summer at a tidal flat in Lake Komuke at the northeast of Hokkaido. Seasonalities of dissolved nitrogen and phosphorus concentrations were also examined to clarify the dynamics of nitrogen and phosphorus in sediment-water interfaces. Salinity decreases during the snowmelt season, and FS revealed that fulvic acid-like and humic acid-like fluorescence intensities were higher in sediment pore water than in surface water especially in tidepool due to accumulation of organic matter production. It is likely that NH4-N and PO4-P concentrations in surface sediment were mainly affected by redox condition change triggered by tidal action and infiltration flow in shore side.
Japan Society of Civil Engineers, 2016, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 72 (4), I_661 - I_666, Japanese[Refereed]
Scientific journal
In Lake Komuke, which is an important lagoon as carbon sinks, we analyzed previous data and found that salinity and biological metabolism (e.g., photosynthesis and respiration as shown by ΔDIC) are the two key environmental factors affecting CO2 fugacity in the water column. Further, the data were analyzed using an approximate expression and the numerical computations using three-dimensional numerical model during spring flood to predict spatial and temporal variation of air-sea CO2 flux. Results show that air-sea CO2 flux changes into negative (i.e., absorption) when the lake is autotrophic with ΔDIC being < -100μmol/kg.
Japan Society of Civil Engineers, 2016, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 72 (2), I_982 - I_987, Japanese[Refereed]
Scientific journal
Field observations of the currents at a bending channel in the Abashiri River in Hokkaido, Japan have revealed an unexpected secondary circulation during flood tide with near-bed and near-surface currents toward the outer and inner banks of the bend, respectively. The direction of these cross-stream currents was reversed at the end of flood tide. The occurrence and shutdown of these observed unexpected secondary circulation were further investigated through the shape of the along-channel velocity profile by using a theoretical solution based on the steady-state momentum equation and the Stokes's second problem for oscillating flow. Also, an advanced numerical model was used to quantify the unexpected secondary flow. It was shown from the theoretical analysis that vertical advection plays a great role in the momentum balance affecting the direction of secondary flows. The typical secondary flow was found to occur throughout ebb tide with a pronounced near-surface maximum velocity profile. Whereas, during flood tide, the longitudinal velocity profile was characterized by a near-bed and mid-depth maximum, resulting an upwelling flow near the outer bank. These findings were reconfirmed by numerical simulations that were conducted for the entire estuary.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2016, Coastal Engineering Journal, 58 (2), 1650002, English[Refereed]
Scientific journal
The awareness of coastal blue carbon is increasing, and the dynamics of the CO2 fugacity (fCO2) in shallow coastal waters are becoming critical for evaluation of CO2 fluxes. We carried out numerical computations using a three-dimensional environmental flow model including snowmelt-related groundwater discharge and estimated fCO2 in water from salinity, biological metabolism, and calcification. Under the influence of the low salinity from the growndwater, fCO2 in water was found to increase slightly as a result of the opposite effect of a decrease in fCO2 with decreasing DIC and an increase in fCO2 with decreasing TA.
Japan Society of Civil Engineers, 2016, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 72 (2), I_1363 - I_1368, Japanese[Refereed]
Scientific journal
- Nov. 2015, 土木学会論文集B2（海岸工学）, 71 (2), I_1033 - I_1038, Japanese超大型浮体構造物が有する津波高さ低減効果の数値解析
[Refereed]
Scientific journal
- Nov. 2015, 土木学会論文集B2（海岸工学）, 71 (2), I_1 - I_6, Japanese河川津波を対象とした強非線形強分散波動方程式によるソリトン波の解析
[Refereed]
Scientific journal
- Jun. 2015, 土木学会論文集B3（海洋開発）, 71 (2), I_913 - I_918, Japaneseマリモ球状体に回転運動を引き起こす阿寒湖チュウルイ湾の風波特性
[Refereed]
Scientific journal
- Jun. 2015, 土木学会論文集B3（海洋開発）, 71 (2), I_217 - I_222, Japaneseオホーツク海における流氷移動ベクトル推定手法に関する検討
[Refereed]
Scientific journal
- Jun. 2015, 土木学会論文集B3（海洋開発）, 71 (2), I_211 - I_216, Japaneseオホーツク海における流氷と波浪・風速の関係について
[Refereed]
Scientific journal
- Mar. 2015, 土木学会論文集B1（水工学）, 71 (4), I_283 - I_288, Japanese生物の細胞組織構造を模した流体シミュレーターの設計と検証
[Refereed]
Scientific journal
- Mar. 2015, 土木学会論文集B1（水工学）, 71 (4), I_793 - I_798, Japanese強非線形強分散3層モデルを用いた成層湖応答解析
[Refereed]
Scientific journal
- Mar. 2015, Journal of JSCE, 71 (4), I_19 - I_24, EnglishNew analytical form of salt intrusion model in funnel shaped estuaries: application to the Abashiri River
[Refereed]
Scientific journal
Total nitrogen (TN), which consists of total particulate nitrogen (TPN) and total dissolved nitrogen (TDN), is transported with not only in river channels but also across the entire river basin, including via ground water and migratory animals. In general, TPN export from an entire river basin to the ocean is larger than TDN in a mountainous region. Since marine derived nutrients (MDN) are hypothesized to be mainly transported as suspended matters from the ground surface, it is necessary to investigate the contribution of MDN to the forest floor (soils) in order to quantify the true role of MDN at the river ecosystem scale. This study investigated TN export from an entire river basin, and also we estimated the contribution of pink (Oncorhynchus gorbuscha) and chum salmon (O. keta) to total oceanic nitrogen input across a river basin. The maximum potential contribution of TN entering the river basin by salmon was found to be 23.8 % relative to the total amount of TN exported from the river basin. The contribution of particulate nitrogen based on suspended sediment from the ocean to the river basin soils was 22.9 % with SD of 3.6 % by using stable isotope analysis (SIA) of nitrogen (δ15N).
Copernicus GmbH, 2015, Biogeosciences Discussions, 12 (21), 18185 - 18211, English[Refereed]
Scientific journal
In Lake Komuke, located in the northeast of Hokkaido, salinity and water level, and groundwater level of the vicinity of tidal flats were observed in the tidal flat in the snowmelt season to summer, and numerical analysis of the infiltration flow accompanied by snowmelt. In field observation results, water level in terrestrial groundwater level and tidal flats, landward groundwater level was higher in the snowmelt season than the other season. From further results of numerical analysis, the salinity in tidal flat was forced not to increase widely in the case of high landward groundwater level than in the case of low landward groundwater level. Moreover, up-welling was slightly strong in the case of high groundwater level, and made sediment salinity lower. The aquatic organisms can live in low salinity zone kept in the tidal flat in the spring season. It is the evidence that the many birds feeding these aquatic organisms in the spring season are frequently observed.
Japan Society of Civil Engineers, 2015, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 71 (2), I_856 - I_861, Japanese[Refereed]
Scientific journal
The eelgrass in Miyako Bay was greatly damaged by the tsunami. For future restoration of the eelgrass, we collected sediments from 110 stations in the bay and analyzed particle-size distribution and chemical composition in 2012 and 2013. The distribution of eelgrass was also measured at the same stations. The sediments on the south and west coast were suitable for eelgrass. On the other hand, the sediments on the east coast were coarser. The chemical composition indicated that we could not expect the supply of sand from the main river to the east coast. We estimated that the restoration of eelgrass on the east coast would be slower than on the west and south coast.
Japan Society of Civil Engineers, Nov. 2014, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 70 (2), 1186 - 1190, Japanese[Refereed]
Scientific journal
- Nov. 2014, 土木学会論文集B2（海岸工学）, 70 (2), I_1186 - I_1190, Japanese宮古湾における津波被害からのアマモ場の復元の可能性について
[Refereed]
Scientific journal
- Nov. 2014, 土木学会論文集B2（海岸工学）, 70 (2), I_1 - I_5, Japanese渦度を考慮した強非線形強分散波動方程式により再現されたソリトン波の解析
[Refereed]
Scientific journal
- Sep. 2014, Proceedings of 19th Congress of the Asia and Pacific Division of the International Association for Hydro-Environment Engineering and Research, 19, EnglishIdentification of the dominant suspended sediment sources in a river basin by using X-ray fluorescence analysis as a fingerprint-type method
[Refereed]
International conference proceedings
- Sep. 2014, Proceedings of 19th Congress of the Asia and Pacific Division of the International Association for Hydro-Environment Engineering and Research, 19, EnglishCharacteristics of river water and nutrient discharge in a wetland
[Refereed]
International conference proceedings
- Jul. 2014, Proceedings of International Conference of Coastal Engineering, 34, EnglishNonlinear oblique interaction of large amplitude internal solitary waves
[Refereed]
International conference proceedings
- Jun. 2014, 土木学会論文集B3（海洋開発）, 70 (2), I_201 - I_206, Japanese異なる斜面勾配における内部ケルビン波の砕波により誘起される流れ
[Refereed]
Scientific journal
- Mar. 2014, 土木学会論文集B1（水工学）, 70 (4), I_1195 - I_1200, Japanese内部ケルビン波の砕波による水平循環の発達と減衰
[Refereed]
Scientific journal
- Mar. 2014, 土木学会論文集B1（水工学）, 70 (4), I_1219 - I_1224, Japanese知床を対象としたMRI-AGCM3.1Sを用いた栄養流出量の将来予測に向けて
[Refereed]
Scientific journal
- Mar. 2014, 土木学会論文集B1（水工学）, 70 (4), I_1585 - I_1590, Japanese汽水湖における有機泥の沈降速度の推定と界面特性に関する考察
[Refereed]
Scientific journal
This study investigates the horizontal and residual circulations in Tokyo Bay using field observations, numerical simulations, and theoretical analysis. Numerical simulations show that the observed deepening of isopycnals and associated anticyclonic horizontal circulation in the bay head are mainly driven by negative wind stress curl. The effects of river discharge, surface heat fluxes, and tides are found to be small. Under strong wind events, the wind stress curl over the bay head can be large enough to make the surface Ekman layer strongly nonlinear. Theoretical and numerical analyses show that, under large negative wind stress curl, the nonlinearity tends to induce positive pumping velocity (at the base of the surface mixed layer) that counteracts the Ekman pumping however, the typical duration of wind events in the bay head is not long enough to induce positive pumping under negative wind stress curl. These results and historical wind data suggest that the average horizontal circulation and residual circulation immediately below the surface mixed layer in Tokyo Bay are, respectively, cyclonic and convergent in summer but anticyclonic and divergent in winter. © 2014. American Geophysical Union. All Rights Reserved.
Blackwell Publishing Ltd, 2014, Journal of Geophysical Research: Oceans, 119 (3), 1977 - 1992, English[Refereed]
Scientific journal
In Lake Komuke, which is one of the most significant lakes for immigration birds, we carried out field experiments of flow field and water quality. Lake Komuke consists of a main lake and the other two small lakes. The main lake is found to have higher salinity compared to the other two small lakes. During the snow melt period, the small lakes are found to have less salinity compared to summer, which is confirmed by the numerical computations using three-dimensional numerical model. As a result, tidal flats in the small lakes have larger residual time of sea water which is significant for immigration birds.
Japan Society of Civil Engineers, 2014, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 70 (2), I_1176 - I_1181, Japanese[Refereed]
Scientific journal
In Lake Komuke, an important flyway in Japan, salinity, water level, and seepage flow were observed in tidal flats and seasonal variation of dissolved organic matters were identified by fluorescence spectroscopy in order to clarify the relationship between water qualities and groundwater flow during spring and summer. At the offshore of the sandbar, the seasonality of fluorescence intensity of fulvic acid-like substances derived from soil in large lake means the seasonal variation of influence of river water and groundwater on water quality in the tidal flat. Groundwater in the tidal flat flew upward by an order of magnitude larger in spring than in summer. From the results of surface water in the tidal flat and the profiles of groundwater, upward flow likely reduces the increase of salinity in the groundwater.
Japan Society of Civil Engineers, 2014, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 70 (2), I_1182 - I_1187, Japanese[Refereed]
Scientific journal
- Dec. 2013, Hydrological Research Letters, 7 (1), 1 - 5, EnglishAdaptive management in Kushiro Wetland in the context of salt wedge intrusion due to sea level rise
[Refereed]
Scientific journal
- Nov. 2013, 土木学会論文集B2（海岸工学）, 69 (2), I_451 - I_455, Japanese内部ケルビン波の砕波による水平循環の発生機構解明
[Refereed]
Scientific journal
- Nov. 2013, 土木学会論文集B2（海岸工学）, 69 (2), I_161 - I_165, Japanese河川津波の進行・発達と河道内における変形に関する解析
[Refereed]
Scientific journal
- Jun. 2013, 土木学会論文集B3（海洋開発）, 69 (2), I_1195 - I_1200, Japanese網走川河口における塩水遡上への吹送流の影響評価
[Refereed]
Scientific journal
- Jun. 2013, 土木学会論文集B3（海洋開発）, 69 (2), I_709 - I_714, Japanese東京湾スケールにおけるメッシュアスペクト比と非静水圧効果の解析
[Refereed]
Scientific journal
- Jun. 2013, Asia Pacific Association of Hydrology and Water Resources (APHW 2013), 18, EnglishSuspended sediment transport in a river basin by using X-ray fluorescence analysis
[Refereed]
International conference proceedings
- May 2013, Hydrological Research Letters, 7 (2), 23 - 29, EnglishHydroclimate projections for Panama in the late 21st Century
[Refereed]
Scientific journal
- Mar. 2013, 土木学会論文集B1（水工学）, 69 (4), I_829 - I_834, Japanese網走川河口域で発生する塩水遡上に関する数値的検討
[Refereed]
Scientific journal
- Mar. 2013, 土木学会論文集B1（水工学）, 69 (4), I_1435 - I_1440, Japanese網走湖におけるメタン発生メカニズムの解明
[Refereed]
Scientific journal
- 2013, Natural Hazards Review, 14 (1), 52 - 65, English
[Refereed]
Scientific journal
- 2013, Hydrological Processes, 27 (23), 3280 - 3291, English
[Refereed]
Scientific journal
- INTERACTION OF SURFACE AND INTERNAL WAVES WITH VERY LARGE FLOATING STRUCTURES
Interaction of surface/internal water waves with a floating platform is discussed with nonlinearity of fluid motion and flexibility of oscillating structure. The set of governing equations based on a variational principle is applied to a one- or two-layer fluid interacting with a horizontally very large and elastic floating thin-plate. Calculation results of surface displacements are compared with the existing experimental data, where a tsunami, in terms of a solitary wave, propagates across one-layer water with a floating thin-plate. We also simulate surface and internal waves due to a point load, such as an airplane, moving on a very large floating structure in shallow water. The wave height of the surface or internal mode is amplified when the moving velocity of point load is equal to the surface or internal wave celerity, respectively.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2013, COASTAL STRUCTURES 2011, VOL 1 & 2, 1, 913 - 922, English[Refereed]
International conference proceedings
Lake Komuke is a typical brackish lake, which is located in the northeastern part of Hokkaido. A lot of birds, such as sipes and plovers, are well known to migrate in Lake Komuke. It is thus important to understand ecological system in Lake Komuke in order to conserve such a significant nature. Mass transport and water quality are the key factors which control ecosystem in an enclosed water body. Therefore, this study aims to clarify the characteristics of water quality and flow field. Conceptual water exchange model was applied and it is revealed that oceanic water intrudes into the lake and the change in surface water level is smaller than the tidal amplitude, which may enhance the primary production of phytoplankton in Lake Komuke.
Japan Society of Civil Engineers, 2013, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 69 (2), I_1228 - I_1233, Japanese[Refereed]
Scientific journal
- Nov. 2012, 土木学会論文集B2（海岸工学）, 68 (2), I_6 - I_10, Japaneseマッハステム形成過程の数値解析
[Refereed]
Scientific journal
- Nov. 2012, 土木学会論文集B2（海岸工学）, 68 (2), I_1 - I_5, Japanese振幅の違いを考慮したソリトン共鳴による大振幅ソリトンの解析
[Refereed]
Scientific journal
- Jul. 2012, Proceedings of International Conference of Coastal Engineering, 33, 1264, EnglishShoaling of nonlinear internal waves on a uniformly sloping beach
[Refereed]
International conference proceedings
- Jul. 2012, Proceedings of International Conference of Coastal Engineering, 33, 1053, EnglishNonlinear oblique interaction of large amplitude internal solitary waves
[Refereed]
Scientific journal
- Jul. 2012, 土木学会論文集B3（海洋開発）, 68 (2), I_745 - I_750, Japanese風と塩水遡上の関連性に関する統計解析
[Refereed]
Scientific journal
- Jul. 2012, 土木学会論文集B3（海洋開発）, 68 (2), I_997 - I_1002, Japanese東京湾を対象としたPartial Cell の適用性の検討
[Refereed]
Scientific journal
- Jul. 2012, 土木学会論文集B2（海岸工学）, 68 (2), I_1096 - I_1100, Japanese河口域における水位変化に伴う浸透流の変動機構
[Refereed]
Scientific journal
- Jul. 2012, 土木学会論文集B2（海岸工学）, 68 (2), I_926 - I_930, Japanese内部ケルビン波の砕波により誘起される流れ
[Refereed]
Scientific journal
- Mar. 2012, 土木学会論文集B1（水工学）, 68 (4), I_1249 - I_1254, Japanese環境流体解析のための簡易Wetting and Dryingスキーム
[Refereed]
Scientific journal
- Mar. 2012, 土木学会論文集B1（水工学）, 68 (4), I_637 - I_642, Japanese元素分析による細粒土砂輸送割合の推定方法開発
[Refereed]
Scientific journal
- Mar. 2012, 土木学会論文集B1（水工学）, 68 (4), I_721 - I_726, Japanese知床を対象とした海陸の栄養塩循環機構の解明
[Refereed]
Scientific journal
- Mar. 2012, Annual Journal of Hydraulic Engineering, JSCE, 68 (4), I_163 - I_168, JapaneseIncrease in simple precipitation intensity index in Panama
[Refereed]
Scientific journal
- INFLUENCE OF VELOCITY DISTRIBUTION AND DENSITY STRATIFICATION ON GENERATION OR PROPAGATION OF TSUNAMIS
A set of wave equations derived on the basis of a variational principle in consideration of both strong nonlinearity and strong dispersion of surface/internal waves is numerically solved to simulate generation and propagation of tsunamis in the vertical two-dimension. The velocity potential in each fluid layer is expanded into a power series of vertical position, such that the accuracy of vertical distribution of velocity depends on the number of expansion terms. Numerical results of surface displacement are compared with the existing experimental data, where tsunamis are generated by the seabed uplift. When the fundamental equations are reduced to nonlinear shallow water equations, the numerical model cannot represent propagation of a long wave group especially in distant-tsunami propagation, leading to overestimation of both the wave height and wave steepness of the first wave. The wave height becomes larger in the stratified ocean than that in a one-layer case, although the present density distribution hardly affects the tsunami phase over a long-distance travel.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2012, ADVANCES IN GEOSCIENCES VOL 28: ATMOSPHERIC SCIENCE (AS) & OCEAN SCIENCE (OS), 67 - 78, English[Refereed]
International conference proceedings
- the 50th ECSA conference, 2012, The 50th Estuaries and Coastal Areas conference, O7.22, EnglishNutrient circulation due to the interaction between terrestrial and oceanic systems
[Refereed]
- 18th Congress of the Asia and Pacific Division of the International Association for Hydro-Environment Engineering and Research, 2012, Proceedings of 18th Congress of the Asia and Pacific Division of the International Association for Hydro-Environment Engineering and Research, 159 - 160, EnglishEstimation of salt wedge intrusion in Kushiro wetland due to sea level rise
[Refereed]
- INFLUENCE OF VELOCITY DISTRIBUTION AND DENSITY STRATIFICATION ON GENERATION OR PROPAGATION OF TSUNAMIS
A set of wave equations derived on the basis of a variational principle in consideration of both strong nonlinearity and strong dispersion of surface/internal waves is numerically solved to simulate generation and propagation of tsunamis in the vertical two-dimension. The velocity potential in each fluid layer is expanded into a power series of vertical position, such that the accuracy of vertical distribution of velocity depends on the number of expansion terms. Numerical results of surface displacement are compared with the existing experimental data, where tsunamis are generated by the seabed uplift. When the fundamental equations are reduced to nonlinear shallow water equations, the numerical model cannot represent propagation of a long wave group especially in distant-tsunami propagation, leading to overestimation of both the wave height and wave steepness of the first wave. The wave height becomes larger in the stratified ocean than that in a one-layer case, although the present density distribution hardly affects the tsunami phase over a long-distance travel.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2012, PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON APAC 2011, 28, 67 - 78, English[Refereed]
International conference proceedings
Interaction of surface/internal water waves with a floating platform is discussed with nonlinearity of fluid motion and flexibility of oscillating structure. The set of governing equations based on a variational principle is applied to a one- or two-layer fluid interacting with a horizontally very large and elastic thin plate floating on the water surface. Calculation results of surface displacements are compared with the existing experimental data, where a tsunami, in terms of a solitary wave, propagates across one- layer water with a floating thin plate. We also simulate surface and internal waves due to a point load, such as an airplane, moving on a very large floating structure in shallow water. The wave height of the surface or internal mode is amplified when the velocity of moving point load is equal to the surface- or internal-mode celerity, respectively.
HINDAWI PUBLISHING CORPORATION, 2012, JOURNAL OF APPLIED MATHEMATICS, 2012, 1 - 14, English[Refereed]
Scientific journal
Residual currents due to internal wave breaking on a uniform slope were investigated in a two-layer system using laboratory experiments and numerical computations for different layer configurations. Internal wave-induced currents over a slope were measured in an experimental tank using PIV and also reproduced by a hydrodynamic model to quantify the detailed velocity field. The present results reveal that the critical level derived from the KdV theorem is a useful parameter for classifying the dynamics of internal waves breaking over a slope. As the horizontal distance from the critical level point to the internal wave breaking point increases, internal waves break more dynamically over the slope. Consequently, residual currents are enhanced near the breaking point. These findings increase our capacity to understand flux paths of biological and chemical substances in the stratified coastal ocean. © 2012. American Geophysical Union. All Rights Reserved.
Blackwell Publishing Ltd, 2012, Journal of Geophysical Research: Oceans, 117 (10), 1 - 11, English[Refereed]
Scientific journal
- 2012, Estuarine, Coastal and Shelf Science, 109, 91 - 97, English
[Refereed]
Scientific journal
- INFLUENCE OF VELOCITY DISTRIBUTION AND DENSITY STRATIFICATION ON GENERATION OR PROPAGATION OF TSUNAMIS
A set of wave equations derived on the basis of a variational principle in consideration of both strong nonlinearity and strong dispersion of surface/internal waves is numerically solved to simulate generation and propagation of tsunamis in the vertical two-dimension. The velocity potential in each fluid layer is expanded into a power series of vertical position, such that the accuracy of vertical distribution of velocity depends on the number of expansion terms. Numerical results of surface displacement are compared with the existing experimental data, where tsunamis are generated by the seabed uplift. When the fundamental equations are reduced to nonlinear shallow water equations, the numerical model cannot represent propagation of a long wave group especially in distant-tsunami propagation, leading to overestimation of both the wave height and wave steepness of the first wave. The wave height becomes larger in the stratified ocean than that in a one-layer case, although the present density distribution hardly affects the tsunami phase over a long-distance travel.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2012, PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON APAC 2011, 6, TSS_07, English[Refereed]
International conference proceedings
- LARGE AMPLITUDE SOLITARY WAVES DUE TO SOLITARY RESONANCE
A fully-nonlinear and strongly-dispersive internal wave equation model was used to investigate the interaction between internal solitary waves in a two-dimensional plane in order to clarify the resonance of fully-nonlinear internal solitary waves, which is one of the reasons for the occurrence of large amplitude solitary waves (LASW). The 3rd order theoretical solutions for internal waves in a two-layer system was used as initial conditions and a "stem" was confirmed to occur when the incident wave angle was less than certain critical angle. This study revealed the occurrence of LASW by using a fully-nonlinear and strongly-dispersive internal wave equation model.
WORLD SCIENTIFIC PUBL CO PTE LTD, 2012, PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON APAC 2011, 6, WME_09, English[Refereed]
International conference proceedings
- Dec. 2011, Hydrological Processes, 24, 2694 - 2702, EnglishInfluence of freshwater input and bay reclamation on long-term changes in seawater residence times in Tokyo Bay, Japan
[Refereed]
Scientific journal
This study aims to evaluate nutrient flux to the coast from the inland areas of Shiretoko in order to understand the key factors controlling the ecological systems of the coast. As an external force, rainfall is considered one of the most significant components controlling nutrient supply to coastal systems in this area. Therefore, to estimate nutrient supply in the future, the bias correction was applied by using Meteorological Research Institute Global Climate Model, which shows good agreement with Automated Meteorological Data Acquisition System data. A synthetic generation technique is used to produce hourly rainfall data, which is necessary for evaluating nutrient supply in Shiretoko. The robustness of the duplicated hourly rainfall intensity was investigated, which reveals that its standard deviation controls nutrient flux when nonlinearity becomes stronger for the evaluation of nutrient supply from a river basin.
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Dec. 2011, Hydrological Research Letters, 5, 47 - 51, English[Refereed]
Scientific journal
- Nov. 2011, 土木学会論文集B2（海岸工学）, 67 (2), I_921 - I_925, Japanese東京湾における貧酸素水塊の解消要因である強風の将来予測に向けて
[Refereed]
Scientific journal
- Nov. 2011, 土木学会論文集B2（海岸工学）, 67 (2), I_6 - I_10, Japaneseソリトン共鳴により発生する大振幅ソリトンの解析
[Refereed]
Scientific journal
- Jul. 2011, 土木学会論文集B3（海洋開発）, 67 (2), I_109 - I_114, Japanese薄板状浮体構造物上を移動する荷重により生成される表面波及び内部波の数値解析
[Refereed]
Scientific journal
- Jul. 2011, 土木学会論文集B3（海洋開発）, 67 (2), I_277 - I_282, Japanese東京湾の水環境予測を目指したGCM データの利用
[Refereed]
Scientific journal
- Jul. 2011, 土木学会論文集B3（海洋開発）, 67 (2), I_511 - I_516, Japanese津波の生成や伝播に対する流速分布及び密度成層の影響
[Refereed]
Scientific journal
- Japan Society of Civil Engineers, Mar. 2011, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 67 (4), 547 - 552, JapaneseANALYSIS OF MECHANISM OF WATER CIRCULATION IN KUSHIRO WETLAND FROM COMPARISONS WITH 1970S
[Refereed]
Scientific journal
- Mar. 2011, 土木学会論文集B1（水工学）, 67 (4), I_1315 - I_1320, Japanese降雨のインパクトによる高濁度水発生と細粒土砂輸送に関する現地観測とモデル化
[Refereed]
Scientific journal
- Mar. 2011, 土木学会論文集B1（水工学）, 67 (4), I_547 - I_552, Japanese1970年代と比較した釧路湿原における水循環機構解析
[Refereed]
Scientific journal
- Mar. 2011, 土木学会論文集B1（水工学）, 67 (4), I_1351 - I_1356, Japanese海面上昇を考慮した釧路湿原への塩水遡上の影響評価
[Refereed]
Scientific journal
- Mar. 2011, 土木学会論文集B1（水工学）, 67 (4), I_1303 - I_1308, Japanese安定同位体比による知床ラウス川を通じた海起源栄養塩の流域内分布
[Refereed]
Scientific journal
Tone River is a shallow, tidal estuary with a controllable upstream freshwater discharge via a barrage. The mixing characteristics in the benthic and interfacial regions of the Tone River estuary were investigated during a time window of maximum freshwater discharge and high shear, using temperature and velocity microstructure measurements. Although the production of turbulent kinetic energy from mean shear was high throughout the water column, the intermittency of both up- and down-gradient buoyancy fluxes resulted in negligible net down-gradient mixing. These opposing fluxes were incorporated into a turbulent closure scheme by using the concept of percentage down-gradient flux. A comparison of vertical diffusivity from two alternative closures suggests that the stratification imposed a length scale limitation on the vertical turbulent excursions that proved crucial for the transition region between the benthic and interfacial regions; it is argued that a Richardson-number based closure is both conceptually and practically adequate to represent the effect of length-scale limitation and percentage down-gradient flux.
TAYLOR & FRANCIS LTD, 2011, JOURNAL OF HYDRAULIC RESEARCH, 49 (6), 791 - 798, English[Refereed]
Scientific journal
Production and transportation of suspended sediment was investigated by sampling surface soils in 18 domains over an entire river basin. Particle size distributions alone suggested that all domains were a source of suspended sediment. Chemical composition analysis however showed that the transport rate of suspended sediment was more closely related to the type of surface soil than to land use. A method was developed which enables estimation of the relative suspended sediment transport rates from each domain of a river basin to its downstream end. The model's validity was verified through good agreement with field sampling results.
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Dec. 2010, Hydrological Research Letters, 4, 55 - 59, English[Refereed]
Scientific journal
This paper uses derived distribution analysis to explore the process controls of the onset of and recovery from hypoxic conditions in Tokyo Bay, Japan. A conceptual, lumped model of dissolved oxygen (DO) dynamics in Tokyo Bay is proposed and, through comparison with a three-dimensional simulation model, is verified to have sufficient accuracy for the prediction of the onset of and recovery from hypoxia. This conceptual DO model was implemented in continuous simulation mode, with 14 years of wind data and data on streamflow entering the Tokyo Bay, and was used to identify and quantify the various process controls of the onset of and recovery from hypoxia. The underlying process controls were identified to be streamflow discharge, as well as duration and strength of both northeast "positive" winds and southwest "negative" winds. The analysis helped to isolate, in particular, the potential for rapid and strong recovery from hypoxia due to "strong negative winds", (i.e., negative winds that exceed a wind speed threshold of 10 m s(-1)) and the critical roles of the duration of these strong winds and the antecedent DO concentration on the strength of DO recovery. Motivated by these results, derived distribution analysis is adopted to predict the strength of DO recovery during periods of strong winds, using a simplified model of DO recovery, focused on isolated strong winds, that explicitly captures the effects of both wind duration and antecedent DO concentration.
AMER GEOPHYSICAL UNION, Dec. 2010, WATER RESOURCES RESEARCH, 46, 1 - 15, English[Refereed]
Scientific journal
- Dec. 2010, Limnology and Oceanography, 55, 1009 - 1023, EnglishResidual circulation due to internal waves shoaling on a slope
[Refereed]
Scientific journal
- Dec. 2010, International Journal for Numerical Methods in Fluids, 62, 574 - 590, EnglishInternal waves in a two-layer system using fully nonlinear internal-wave equations
[Refereed]
Scientific journal
This study aims to reveal the factors most useful for evaluating the influence of wind on entrainment from the lower to upper layer in a two-layer system. Lake Abashiri, which is a typical brackish lake, is chosen as a study area because a distinct two-layer system exists due to salt-wedge intrusion from the ocean. To evaluate entrainment velocity between two layers, a 3D numerical computation is applied, showing good agreement with field observations. Computations suggest that the entrainment velocity estimated using the Richardson number is smaller than that from field observations. Thus, other factors are computed suggesting that use of the Lake number is more effective in estimating entrainment velocity due to internal wave breaking and interfacial fluctuation than use of the Effective Wedderburn number.
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Dec. 2010, Hydrological Research Letters, 4, 70 - 74, English[Refereed]
Scientific journal
Applicability of the 3rd order theoretical solutions for internal waves in a two-layer system is investigated by using a strongly nonlinear and dispersive internal wave model. The 3rd order solution is derived using the 9th order internal wave equations. The 3rd order solution is found to give larger wavelength scale compared to KdV theory. The applicability of the 3rd order solution is confirmed to be high when the amplitude of internal solitary wave is 5% of the lower layer thickness. A fully nonlinear strongly dispersive internal wave model reveals that high frequency internal waves are induced behind an internal solitary wave when the initial shape of internal solitary wave is larger than critical level.
Japan Society of Civil Engineers, Nov. 2010, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 66 (1), 1 - 5, Japanese[Refereed]
Scientific journal
- Nov. 2010, 海岸工学論文集, 57, 326 - 330, Japanese塩水遡上へ与えるストークスドリフトの影響評価
[Refereed]
Scientific journal
- Nov. 2010, 海岸工学論文集, 57, 1 - 5, Japanese内部ソリトン波の3次オーダ解による再現性の検討
[Refereed]
Scientific journal
- Nov. 2010, 海岸工学論文集, 57, 171 - 175, Japanese深水域や砕波点近傍における非線形内部波の挙動
[Refereed]
Scientific journal
- Jul. 2010, Proceedings of International Conference of Coastal Engineering, 32, EnglishInfluence of Stokes drift on salt wedge intrusion evaluated using fully-nonlinear and strongly dispersive wave equations
[Refereed]
Scientific journal
- Jul. 2010, 海洋開発論文集, 26, 789 - 794, Japanese釧路湿原への塩水遡上に関する調査と検討
[Refereed]
Scientific journal
- Jul. 2010, 海洋開発論文集, 26, 657 - 662, Japanese東京湾を対象とした内部ケルビン波の発生と砕波に関する検討
[Refereed]
Scientific journal
- Mar. 2010, 水工学論文集, 54, 43 - 438, Japanese融雪期における高濁度水発生機構と細粒土砂輸送
[Refereed]
Scientific journal
- Mar. 2010, 水工学論文集, 54, 1393 - 1398, Japanese網走湖における密度界面に対する風応力と河川流入の影響評価
[Refereed]
Scientific journal
- 5th Conference of the APHW, 2010, 5th Conference of the APHW, 428 - 435, EnglishMass transport and nutrient circulation evaluated by stable isotope analysis and chemical decomposition,
[Refereed]
- International Symposium on Ecohydraulics, 2010, International Symposium on Ecohydraulics 2010, 133 - 141, EnglishInfluence of internal waves on interfacial level in Lake Abashiri
[Refereed]
- A NUMERICAL STUDY ON PROPAGATION OF NONLINEAR INTERNAL WAVES
Internal waves in a two-layer system are simulated using a set of nonlinear internal-wave equations, which was derived on the basis Of a variational principle without any assumptions concerning wave nonlinearity and dispersion In the cases where long internal waves reflect in a tank, interface displacements obtained by the proposed model with more than two vertically distributed functions of velocity potential are in harmony with those by the Boussinesq-type model. as well as the existing experimental data especially in the wave number In the intermediate-wave case, the present model shows different results from those through the Boussinesq-type model, which should not be applied to this case without enough consideration of the wave dispersion Internal waves propagating over a submerged breakwater are also simulated, where the vertical distribution of horizontal velocity below a crest is remarkably distributed when it starts disintegration after passing over the shoulder
WORLD SCIENTIFIC PUBL CO PTE LTD, 2010, PROCEEDINGS OF THE 5TH INTERNATIONAL CONFERENCE ON ASIAN AND PACIFIC COASTS, VOL 3, 32, 208 - +, English[Refereed]
International conference proceedings
This paper describes the influence of surface waves on salt-wedge intrusion in terms of radiation stress. Radiation stress which includes Stokes drift effect may increase salt-wedge intrusion when surface waves propagate up a river. This study thus aims to reveal the effect of radiation stress on the distance of salt-wedge intrusion by fully nonlinear strongly dispersive internal wave equations and three-dimensional numerical computation model, Fantom3D. Fully nonlinear strongly dispersive internal wave model reveals the possibility that large radiation stress is induced near the river mouth and increases the distance of salt-wedge intrusion. Three-dimensional numerical model also demonstrates that there is a significant difference in the intrusion distance by taking into account radiation stress.
Japan Society of Civil Engineers, 2010, PROCEEDINGS OF THE JAPANESE CONFERENCE ON COASTAL ENGINEERING, 66 (1), 326 - 330, EnglishA set of nonlinear internal-wave equations, which have been derived on the basis of the variational principle without any assumptions concerning wave nonlinearity and dispersion, is applied to compare numerical results with experimental data of internal waves propagating in a deep-water region. Internal waves propagating over a uniformly sloping beach are also simulated. Internal progressive waves show remarkable shoaling after the interface reaches the critical level, after which the physical variables change discontinuously near the wave-breaking point. In the wave-breaking case of internal waves reflecting at a vertical wall, the vertical velocity of the particles in the vicinity of the interface is different from that of the moving interface on the wall, which means that the kinematic boundary condition on the interface is not satisfied.
Japan Society of Civil Engineers, 2010, PROCEEDINGS OF THE JAPANESE CONFERENCE ON COASTAL ENGINEERING, 66 (1), 26 - 30, EnglishThe paper describes the effect of a stair-step representation of bottom topography, common in most numerical models, on the propagation of internal waves in a geophysical flow. An analytical solution was used to predict the effect of stair-step and piecewise linear representations of topography on the reflection and transmission of internal waves. The Estuary Lake and Coastal Model (ELCOM) was used to simulate the transmission of a train of small-amplitude internal gravity waves propagated along a variable depth rectangular channel containing a linearly stratified fluid. The effect of the different obstacle approximations was examined in terms of the interference of the resulting wave number content, and hence the associated reflection coefficients, which could be directly compared to the analytical theory. It was shown that for Gaussian obstacles of varying lengths and heights, the full bottom cells and partial bottom cells solutions from ELCOM agree with the stair-step and piecewise linear solutions from the theory, respectively. It was shown that when Gaussian obstacles with weak slopes are represented by stair steps, an aliasing that is similar to that in discrete Fourier transform can occur, resulting in reflection coefficients that are much higher than the exact solution. On the other hand, piecewise linear approximations produce significantly attenuated aliasing. An immersed boundary technique that enforces a no-flux condition at the actual sloping bottom, similar to that of the analytical solution, is found not to produce better numerical results. Copyright 2009 by the American Geophysical Union.
Blackwell Publishing Ltd, 08 Dec. 2009, Journal of Geophysical Research: Oceans, 114 (12), English[Refereed]
Scientific journal
- Dec. 2009, Hydrological Processes, 23, 534 - 545, EnglishEffects of spatial grid resolution on river flow and surface inundation simulation by physically based distributed modelling approach
[Refereed]
Scientific journal
The paper describes the effect of a stair-step representation of bottom topography, common in most numerical models, on the propagation of internal waves in a geophysical flow. An analytical solution was used to predict the effect of stair-step and piecewise linear representations of topography on the reflection and transmission of internal waves. The Estuary Lake and Coastal Model (ELCOM) was used to simulate the transmission of a train of small-amplitude internal gravity waves propagated along a variable depth rectangular channel containing a linearly stratified fluid. The effect of the different obstacle approximations was examined in terms of the interference of the resulting wave number content, and hence the associated reflection coefficients, which could be directly compared to the analytical theory. It was shown that for Gaussian obstacles of varying lengths and heights, the full bottom cells and partial bottom cells solutions from ELCOM agree with the stair-step and piecewise linear solutions from the theory, respectively. It was shown that when Gaussian obstacles with weak slopes are represented by stair steps, an aliasing that is similar to that in discrete Fourier transform can occur, resulting in reflection coefficients that are much higher than the exact solution. On the other hand, piecewise linear approximations produce significantly attenuated aliasing. An immersed boundary technique that enforces a no-flux condition at the actual sloping bottom, similar to that of the analytical solution, is found not to produce better numerical results.
AMER GEOPHYSICAL UNION, Dec. 2009, JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 114, 1 - 21, English[Refereed]
Scientific journal
- Nov. 2009, 海岸工学論文集, 56, 66 - 70, Japanese潜堤上における非線形内部波の伝搬特性
[Refereed]
Scientific journal
- Sep. 2009, River, Estuary and Coastal Morphodynamics, 6, 183 - 188, EnglishReproduction of flow over sand waves using the variation principle
[Refereed]
Scientific journal
- Jul. 2009, Proc. 5th Int. Conf. on Asian and Pacific Coasts, 3, 208 - 214, EnglishA numerical study on propagation of nonlinear internal waves
[Refereed]
Scientific journal
- Jul. 2009, 海洋開発論文集, 25, 1041 - 1046, Japanese東京湾スケールの流動が京浜運河に与える影響評価
[Refereed]
Scientific journal
- Mar. 2009, 水工学論文集, 53, 1267 - 1272, Japanese環境流体解析を目的としたオブジェクト指向型流体モデルの開発と検証
[Refereed]
Scientific journal
- Mar. 2009, 水工学論文集, 53, 1321 - 1326, Japanese斜面上での内部波の砕波形態と物質輸送
[Refereed]
Scientific journal
- Mar. 2009, 水工学論文集, 53, 1087 - 1092, Japanese変分原理を用いた河床波上の流れの再現とその適用性
[Refereed]
Scientific journal
- Mar. 2009, 水工学論文集, 53, 1285 - 1290, Japanese網走湖における内部ケルビン波と風応力の影響評価
[Refereed]
Scientific journal
Internal waves propagating over a submerged breakwater in a two-layer system are numerically simulated using a set of nonlinear internal-wave equations derived on the basis of a variational principle without any assumptions concerning wave nonlinearity and dispersion. When an internal-wave crest starts wave disintegration after passing over an offshore shoulder of submerged breakwater, both the horizontal velocity and dynamic pressure below the internal-wave crest show a remarkable distribution or a remarkable curvature of distribution in the vertical direction with wave dispersion. Over a submerged breakwater where the width of the breakwater crown is short or the lower-layer depth is deep over the breakwater crown, the crests of internal waves do not show wave disintegration.
Japan Society of Civil Engineers, 2009, PROCEEDINGS OF THE JAPANESE CONFERENCE ON COASTAL ENGINEERING, 65 (1), 66 - 70, English- THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2009, Proceeding of Annual Conference, 22, 60 - 60, Japanese
- Mar. 2008, 水工学論文集, 53, 193 - 198, Japanese東京湾の湾奥底層DO濃度に対する強風イベントの統計的解析
[Refereed]
Scientific journal
- Dec. 2007, Journal of Environmental Engineering - ASCE, 133 (4), 447 - 453, EnglishModeling of dissolved oxygen in an enclosed bay with sill
[Refereed]
Scientific journal
- Dec. 2007, Hydrological Research Letters, 62, 574 - 590, EnglishA numerical study on internal waves induced by a typhoon around a continental shelf
[Refereed]
Scientific journal
- Nov. 2007, 海岸工学論文集, 55, 376 - 380, Japanese斜面上での内部波の砕波機構と残差流
[Refereed]
Scientific journal
- Nov. 2007, 海岸工学論文集, 55, 6 - 10, Japanese渦度を考慮した非線形波動方程式による表面波及び内部波の数値解析
[Refereed]
Scientific journal
We calculated the monthly residence time of seawater in the inner bay of Tokyo Bay during August 2002 to June 2003 and compared it with a monthly residence time of seawater averaged from 1947 to 1974. The residence time of seawater was calculated by dividing the volume of the inner bay by an exchange rate between the inner bay and the outer bay. The exchange rate was calculated by using the monthly averaged salinity in the inner bay and the outer bay, and freshwater discharge in the inner bay. Between the years of 1947 to 1974, estimations from past studies were used to calculate the average monthly salinity. During August 2002 to June 2003, insitu salinity measurements were conducted 22 times at 27 stations within Tokyo Bay. The freshwater discharge into the inner bay was calculated from the catchment area precipitation and water mass imported from the neighboring catchment area for both data sets. From the results, the residence time of seawater during 2002 consisted of an annual mean of 31 days, with seasonal residence times of 19 days during summer and 43 days during winter. On the other hand, during 1947-1974, the mean annual residence time of seawater was 48 days, with summer and winter seasonal durations of 28 days and 79 days respectively. Thus seawater residence time in the inner bay during 2002 was greatly reduced them previous long-term estimations, by approximately 35%.
Japan Society of Civil Engineers, Nov. 2007, 土木学会論文集, 63 (1), 67 - 72, Japanese[Refereed]
Scientific journal
- Nov. 2007, 陸水学会誌, 68 (2), 241 - 251, Japaneseアオコ流動モデルを用いた天竜川の藍藻Microcystis細胞濃度の時間変動予測
[Refereed]
Scientific journal
- Jul. 2007, 海洋開発論文集, 24, 633 - 638, Japanese東京湾奥における底層DOに対する風および河川流入の影響評価
[Refereed]
Scientific journal
- Jul. 2007, 海洋開発論文集, 24, 763 - 768, Japanese芝浦運河 海の顔・川の顔調査
[Refereed]
Scientific journal
- Mar. 2007, Annual Journal of Hydraulic Engineering, JSCE, 52, 199 - 204, JapaneseDevelopment of a conceptual model for dissolved oxygen concentrations considering flood event effects in Tokyo Bay
[Refereed]
Scientific journal
- Mar. 2007, Annual Journal of Hydraulic Engineering, JSCE, 52, 169 - 174, JapaneseNumerical simulation of internal waves using a set of fully nonlinear internal-wave equations
[Refereed]
Scientific journal
- Mar. 2007, 水工学論文集, 52, 1385 - 1390, Japanese一様な斜面上で砕波する内部ケルビン波により誘起される流れ
[Refereed]
Scientific journal
- CHINA OCEAN PRESS, 2007, ASIAN AND PACIFIC COASTS 2007, 5, 295 - +, EnglishA numerical study on stratified flows induced by a typhoon in a bay and around a continental shelf
[Refereed]
International conference proceedings
The effect of Tama river inflow into Tokyo Bay on dissolved oxygen in bottom layer has been analyzed using numerical simulation by ELCOM- CAEDYM and field observation. The result implied that the Tama River inflow may contribute the decrease of dissolved oxygen, however further evaluation should be made for further evaluation.
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2007, Proceeding of Annual Conference, 20, 88 - 88, Japanese- Dec. 2006, Ocean Engineering, 33 (14), 1896 - 1918, EnglishNumerical study on the flow characteristics of tidal jets induced by a tidal-jet-generator
[Refereed]
Scientific journal
- Dec. 2006, International Journal for Numerical Methods in Fluids, 51, 197 - 219, EnglishComparisons of CIP, compact and CIP-CSL2 schemes for reproducing internal solitary waves
[Refereed]
Scientific journal
- 日本沿岸域学会, Dec. 2006, 沿岸域学会論文集, 18 (4), 67 - 77, Japanese2003年東京湾に発生した繊毛虫Mesodinium rubrumによる赤潮と水生生物の大量死の連関に関する調査事例
[Refereed]
Scientific journal
- Nov. 2006, 海岸工学論文集, 53, 361 - 365, Japanese台風により大陸棚近傍に生成される内部波の数値解析
[Refereed]
Scientific journal
- Jul. 2006, 海洋開発論文集, 22, 829 - 834, Japanese東京湾における季節特性を考慮した湾内流動の再現計算
[Refereed]
Scientific journal
- Jul. 2006, 海洋開発論文集, 22, 817 - 822, Japanese湾口部にシルをもつ湾における底層貫入とDO濃度に関する観測と数値実験
[Refereed]
Scientific journal
- Jul. 2006, 海洋開発論文集, 22, 793 - 798, Japanese東京湾奥における出水時の河川水挙動に関する基礎的研究
[Refereed]
Scientific journal
- Mar. 2006, 水工学論文集, 50, 1387 - 1392, Japanese河口部に設置された円柱による河口周辺での乱れエネルギーに関する検討
[Refereed]
Scientific journal
- 2006, 水工学論文集, 50, 1378 - 1392円柱による乱れが河口の塩水侵入に与える影響評価
- Dec. 2005, Estuarine Coast and Shelf Science, 64, 459 - 466, EnglishMechanism responsible for fortnightly modulations in estuarine circulation in Tokyo Bay
[Refereed]
Scientific journal
- Nov. 2005, 海岸工学論文集, 52, 306 - 310, Japanese強風の吹き寄せにより密度成層水域に生成する流れ場の 3 次元数値計算
[Refereed]
Scientific journal
- Nov. 2005, 土木学会論文集, 789, 59 - 71, Japanese斜面に連続的に作用する内部界面の理論解の適用性の検討
[Refereed]
Scientific journal
- Nov. 2005, 水文水資源学会誌, 18 (4), 390 - 400, Japanese河道モデルと沿岸流動モデルの統合とその必要性に関する検討
[Refereed]
Scientific journal
- Sep. 2005, River, Estuary and Coastal Morphodynamics, 4, 1027 - 1034, EnglishModeling the effect of stratification on sediment deposition
[Refereed]
Scientific journal
- Jul. 2005, 海洋開発論文集, 21, 379 - 384, Japanese東京湾における散逸率の縦断分布と鉛直混合
[Refereed]
Scientific journal
- Mar. 2005, 水工学論文集, 49, 1297 - 1302, Japanese東京湾の湾奥における時計回りの循環と収束現象の解明
[Refereed]
Scientific journal
- Mar. 2005, 水工学論文集, 49, 1291 - 1296, Japanese東京湾湾口部におけるフロント形成過程の究明
[Refereed]
Scientific journal
- 2005, MTERM International Conference, 207 - 214, EnglishA Comparative Analysis of River Flow Modeling in an Urban River Basin in Japan Using Lumped and Physically Based Approaches
[Refereed]
International conference proceedings
- Nov. 2004, 海岸工学論文集, 51, 16 - 20, Japanese固定グリッドにおいて遡上波を追跡する計算手法の開発
[Refereed]
Scientific journal
- Nov. 2004, 土木学会論文集, 754, 33 - 50, Japanese荒川河口域における潮差変動に伴うChlorophyll a分布および河川流入負荷量の変動
[Refereed]
Scientific journal
- Mar. 2004, 水工学論文集, 48, 1243 - 1248, Japanese2002年東京湾の海水の滞留時間とマルチボックス鉛直1次元モデルを用いた再現計算
[Refereed]
Scientific journal
- Mar. 2004, 水工学論文集, 48, 793 - 798, Japanese高瀬川の浅瀬が塩水遡上に与える影響について
[Refereed]
Scientific journal
- Mar. 2004, 水工学論文集, 48, 1219 - 1224, Japanese2成層場におけるソリトンに対する新たなスキームの適用と検討
[Refereed]
Scientific journal
- Nov. 2003, 陸水学会誌, 64 (2), 121 - 131, Japanese移流拡散モデルを用いた天竜川の藍藻Microcystisの動態解析
[Refereed]
Scientific journal
- Nov. 2003, 計算工学講演会論文集, 8, 1 - 4, Japanese有限要素CIP-mスキームを用いた流況予測シミュレーション
[Refereed]
Scientific journal
- Nov. 2003, 海岸工学論文集, 50, 141 - 145, Japanese斜面に連続的に作用する内部波の砕波と残差流
[Refereed]
Scientific journal
- Nov. 2002, 海岸工学論文集, 49, 1021 - 1025, Japanese荒川河口域にけるChl-aの鉛直分布
[Refereed]
Scientific journal
- Nov. 2002, 海岸工学論文集, 49, 1051 - 1055, Japanese総合的内湾水質評価モデルの構築と東京湾への適用
[Refereed]
Scientific journal
- Nov. 2002, 海岸工学論文集, 49, 1031 - 35, Japanese二枚貝が優占する湖沼の水塊形成に関する数値解析
[Refereed]
Scientific journal
- Nov. 2001, 海岸工学論文集, 48, 1051 - 1055, Japanese湖沼の平面的な水塊分布構造に及ぼす水表面熱収支の影響
[Refereed]
Scientific journal
- Nov. 2001, 海岸工学論文集, 48, 1086 - 1090, Japanese夏期の東京湾湾奥における表層の植物プランクトンに対する底層栄養塩の影響
[Refereed]
Scientific journal
- Nov. 2001, 海洋工学シンポジウム, 16, 43 - 48, Japanese内湾における環境問題の展開と環境シミュレーション
[Refereed]
Scientific journal
- Nov. 2001, 海洋工学シンポジウム, 16, 59 - 66, Japanese内湾の環境評価を目指したMEL1D-MBモデルの構築と東京湾への適用
[Refereed]
Scientific journal
- Nov. 2001, 土木学会論文集, 691, 25 - 41, Japanese融雪を考慮した山地流出モデルに関する研究
[Refereed]
Scientific journal
- Nov. 2001, Journal of Hydroscience and Hydraulic Engineering, 19 (2), 105 - 117, EnglishInternal wind waves and snow clouds on a mountain slope
[Refereed]
Scientific journal
- 国土交通省港湾技術研究所, Jun. 2001, 港湾技研資料, (1003), 1 - 21, Japanese東京湾湾奥部におけるChl-a(植物プランクトン量)空間分布評価モデルに関する検討
- 国土交通省港湾技術研究所, Jun. 2001, 港湾技研資料, (1004), 1 - 15, Japanese閉鎖性内湾の底層溶存酸素濃度に対する湾口防波堤の影響
- 国土交通省港湾技術研究所, Mar. 2001, 港湾技研資料, (989), 1 - 15, Japanese界面渦等により不連続化した流れ場再現プログラムCIP-m-FEMの開発
- Mar. 2001, 水工学論文集, 45, 1147 - 1152, Japanese湖沼の物質循環に及ぼす夜間の水面冷却の影響
[Refereed]
Scientific journal
- Mar. 2001, 水工学論文集, 45, 595 - 600, Japanese常射流混在場における有限要素CIP-mスキームの構築
[Refereed]
Scientific journal
- Nov. 2000, 海岸工学論文集, 47, 1041 - 1045, Japanese大船渡湾における底層DO濃度の変動に及ぼす湾外の影響
[Refereed]
Scientific journal
- Nov. 2000, 海岸工学論文集, 47, 421 - 425, Japanese大潮, 小潮期における湾外水の影響
[Refereed]
Scientific journal
- 01 Jun. 2000, 港湾技術研究所報告, 39 (2), 47 - 72内湾域の水環境に影響を及ぼす物理的要因に関する考察-瀬戸内海総合水質調査データによる解析-
[Refereed]
Scientific journal
- 国土交通省港湾技術研究所, 01 Jun. 2000, 港湾技術研究所報告, 39 (2), 73 - 98, Japanese大船渡湾における湾外水の密度変動が湾内水環境に及ぼす影響の定量的評価
[Refereed]
Scientific journal
- Mar. 2000, 水工学論文集, 44, 945 - 950, Japanese湾内外の密度差による湾口部での流出入機構
[Refereed]
Scientific journal
- Mar. 2000, 水工学論文集, 44, 801 - 806, Japanese樹林群を考慮した浅水流モデル
[Refereed]
Scientific journal
- Mar. 2000, 水工学論文集, 44, 879 - 884, Japanese成層場における固液混相流LESモデルの開発
[Refereed]
Scientific journal
- Mar. 2000, 水工学論文集, 44, 1056 - 1060, Japanese東京湾における成層期の流れ場
[Refereed]
Scientific journal
A two-dimensional finite-element model using depth-averaged Navier-Stokes equations with primitive variables is used to simulate flow in Kanmon Strait, an important navigation channel in the Japanese archipelago. It is concluded from this study that the strait, like all narrow water bodies connecting two open seas, reflects most of the energy of any wave propagating from one open sea and allows very small part of the energy to be transmitted through the narrow channel. Hence, a steep water surface gradient is generated inside the strait producing high velocities. The model, like other depth-averaged models, reasonably predicts water level and velocity direction and phase. However, they underpredict velocity values because they do not take into account effect of secondary currents.
2000, Coastal Engineering 2000 - Proceedings of the 27th International Conference on Coastal Engineering, ICCE 2000, 276, X3861 - 3869, English[Refereed]
International conference proceedings
- Dec. 1999, Journal of Hydroscience and Hydraulic Engineering, 17 (2), 127 - 138, EnglishCold air flow and simulation of snow clouds
[Refereed]
Scientific journal
- Nov. 1999, 土木学会論文集, 628, 97 - 114, JapaneseLESモデルによる水平面上張り出しプルームの解析
[Refereed]
Scientific journal
- Mar. 1999, 水工学論文集, 43, 365 - 370, Japanese射流場におかれた円柱周辺の流れの解析
[Refereed]
Scientific journal
- Mar. 1999, 水工学論文集, 43, 31 - 36, Japanese矩形グリッドを用いた山地流出解析
[Refereed]
Scientific journal
- Mar. 1999, 水工学論文集, 43, 257 - 262, Japanese内部波が山地斜面の大気に及ぼす影響
[Refereed]
Scientific journal
- Dec. 1998, Journal of Hydroscience and Hydraulic Engineering, 16 (1), 9 - 25, EnglishA study on a wind field when a cold air flow that causes snowfall around Sapporo
[Refereed]
Scientific journal
- Dec. 1998, Journal of Hydroscience and Hydraulic Engineering, 16 (2), 35 - 48, EnglishA numerical study on a cold air flow causing the formation of snow clouds over Sapporo City
[Refereed]
Scientific journal
- Nov. 1998, 土木学会論文集, 593 (593), 1 - 10, Japanese冬期石狩湾における陸からの冷気流フロント上に発生する降雪雲観測
[Refereed]
Scientific journal
- Nov. 1998, 土木学会論文集, 607, 1 - 17, Japanese降雪をともなう冷気流に関する実験および数値計算予測
[Refereed]
Scientific journal
- Mar. 1998, 水工学論文集, 42, 31 - 36, Japanese陸から海上へ張り出す冷気流と雪雲発生予測に関する研究
[Refereed]
Scientific journal
- Mar. 1998, 水工学論文集, 42, 1159 - 1164, JapaneseCIP法を用いた浅水流方程式の数値計算手法の開発
[Refereed]
Scientific journal
- Mar. 1998, 水工学論文集, 42, 1141 - 1146, Japanese全流域を矩形グリッドで覆いSGS効果を考慮した浸透流方程式を用いた流出予測
[Refereed]
Scientific journal
- Mar. 1997, 水工学論文集, 41, 19 - 134, Japanese雪雲発生要因である冷気流に関する数値実験的研究
[Refereed]
Scientific journal
- Nov. 1996, 土木学会論文集, 539, 31 - 42, Japanese冬期石狩湾において豪雪をもたらす冷気流張り出しに関する研究
[Refereed]
Scientific journal
- Mar. 1996, 水工学論文集, 40, 267 - 272, Japanese札幌周辺に豪雪をもたらす冷気流発生時における風の場に関する研究
[Refereed]
Scientific journal
- Mar. 1995, 水工学論文集, 39, 177 - 182, Japanese冬期石狩湾における鉛直断面内の冷気流形状に関する研究
[Refereed]
Scientific journal
- INT ASSOC HYDROLOGICAL SCIENCES, 1994, SNOW AND ICE COVERS: INTERACTIONS WITH THE ATMOSPHERE AND ECOSYSTEMS, (223), 177 - 186, EnglishANALYSIS OF WIND FIELDS IN WINTER BY USING AMEDAS AND CONSIDERING TOPOGRAPHY
[Refereed]
International conference proceedings
- Mar. 2023, Journal of Environmental Sciences
Scientific journal
Springer Science and Business Media {LLC}, Dec. 2021, Scientific Reports, 11 (1), EnglishScientific journal
Regarding the reduction of atmospheric CO2, the function of CO2 absorption in coastal areas has been drawing attention. In this study, we developed a numerical model of pCO2 dynamics considering effects of freshwater inflow based on the results of field observation in the Yatsushiro Sea, to obtain the basic knowledge about CO2 dynamics in coastal areas. The model was able to reproduce well the tempo-spatial distribution of pCO2 and the distribution of salinity and water temperature under different stratification conditions. From the results of the hindcast simulation, it was confirmed that the amount of CO2 absorbed around the estuary fluctuated greatly spatiotemporally with the big flood. Furthermore, the following two effects of the freshwater inflow on the dynamics of CO2 in the coastal area are confirmed as follows: i) After flooding, CO2 release can be promoted by the suface freshwater capping; and ii) After mixing of freshwater and seawater, CO2 absorption can be promoted by photosynthesis due to blooming of phytoplankton in the surface layer.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 77 (2), I_847 - I_852, JapaneseIt has been observed that a periodic water surface oscillation ocurrs downstream of a drop structure with a trench at specific hydraulic and geometric conditions. In order to establish a relationship governing the oscillation frequency, a number of experiments using flow visualization and image analysis techniques were conducted. As a result, we proposed a Strauhal number specific to the oscillating hydraulic jump. In addition, a numerical simulations based on SST 𝑘-𝜔 model was executed to successfully simulate time varying oscillating flow comparable to the experiment.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 77 (2), I_871 - I_876, JapaneseIn lakes and the ocean, pycnocline is formed due to solar radiation and inflow into the coastal area, on which internal waves are generated by external forces, such as wind stress and tide. Internal waves propagate and break over a topographical slope, resulting in the long-term transport of nutrients, methane, carbon, hypoxia, and other water quality components and the deterioration of the ecological system. Internal solitary waves are revealed to have considerable kinetic energy and affect mass transport. Among internal solitary waves, "breather" is found to exist in a three-layer fluid, but the mechanism of the breather breaking over a slope remains unsolved. Thus, this study aims to clarify how breathers deform over the topographical change and break on a uniform slope by using a three-dimensional numerical model. We revealed that the classification for an internal solitary wave breaking is successfully applied to categorize the breaking type of breathers over a slope.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 77 (2), I_343 - I_348, JapaneseIn a two-layer fluid, when pycnocline thickness is negligible, an internal solitary wave (ISW) breaking over a slope can be categorized into four breaker types: surging, collapsing, plunging, and fission breakers. The latest classification into four breaker types is based on wave slope, bottom slope gradient and an internal Reynolds number. However, it remains unsolved if this classification can categorize the breaking of an ISW under thick pycnocline conditions. This study uses numerical simulations to investigate the applicability of the classification under changing pycnocline thickness. We found that the classification can categorize all breaker types even when pycnocline thickness varies. Additionally, thicker pycnoclines result in more significant energy loss and onshore mass transport energy loss due to ISW breaking.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 77 (1), 59 - 73, JapaneseThe surface velocity coefficient is the value that converts the surface velocity into the depth-averaged velocity when observing the discharge, and 0.85 is treated as the standard value in Japan. In recent years, surface velocity measurement by STIV is widely used, but only surface flow information can be obtained. Therefore, it is important to properly determine the coefficient when estimating the discharge. In this paper, we focused on the situation where the water depth gradually changes due to the formation of sandbars. We conducted flume experiments to examine the response characteristics of the surface velocity and the surface velocity coefficient caused by changes in the riverbed slope. As a result, it was shown that the change of the correction coefficient is not symmetrical with respect to the riverbed topography, and that the coefficient decreases sharply on the downstream side of the sandbar because the influence of negative acceleration is large. The above characteristics are verified through numerical simulations as well.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 77 (2), I_877 - I_882, JapaneseAegagropila linnaei, Marimo, is a special natural monument of Japan and in danger of extinction. However, the formation mechanism of Marimo has been unresolved. In particular, it is needed to estimate the rotation angle of Marimo, which plays a significant role in the formation of Marimo. Numerical computation is one of the most robust techniques. Thus, we attempted to develop the Marimo model, including the Marimo's movement and its rotation. The Marimo model showed a relatively good reproducibility with the laboratory experiments in terms of rotation when the Marimo was in contact. However, when they were not in contact, the model did not reproduce well. It was also suggested that the rotational moment needs to be taken into account.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 77 (2), I_1063 - I_1068, JapaneseCigu Lagoon is a famous lagoon for fish agriculture (oyster) and migration birds, where few seagrasses exist. We aim to investigate the environmental factors affecting carbon fluxes in Cigu Lagoon to understand the influence of fishery. SEM analysis was conducted to understand the influence of environmental factors on the air-sea CO2 flux. The results suggest that the CO2 flux is directly influenced by wind speed and indirectly by pH due to the influence of oysters. A three-dimensional environmental model, Fantom, was applied to investigate the effect of the wind on DIC at the water surface. It was demonstrated that strong wind enhances the vertical convection in the water column, resulting in high DIC at the water surface due to the mixing with higher DIC adjacent to the sea bottom.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 77 (2), I_841 - I_846, Japanese"Blue carbon", absorbed carbon by photosynthesis in coastal and ocean ecosystem, has been paid attention to as climate change mitigation. The carbon absorption rate varies when seagrass bends due to current, suggesting the necessity of precise estimation of carbon absorption by the blue carbon ecosystem. We developed the Submerged Aquatic Vegetation model (SAV model), which combines SAV motion and its interaction with the current. Therefore, this study aims to verify the SAV model's validity by applying laboratory experiments in an open channel assuming low-density polyethylene as SAV, which agreed with the laboratory experiments.
Japan Society of Civil Engineers, 2021, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 77 (2), I_205 - I_210, Japanese- Sep. 2020, 土木学会年時講演会講演集, 73琵琶湖における高精度な流動場の解析手法の提案
- 2020, 65, Ⅰ_1063 - 1068, Japanese浅水状態の粗配置桟粗度上で生じる三角状水面波列に対するソリトン解の適用—APPLICATION OF SOLITON SOLUTION TO TRIANGULE-SHAPE WATER SURFACE WAVE SEQUENCE WITH SPARSELY DISTRIBUTED STRIP ROUGHNESS IN SHALLOW WATER
- 2020, 65, Ⅰ_1399 - 1404, Japanese内部ソリトン波の砕波によるエネルギー減衰のモデル化と成層流動場の高精度な再現—ENERGY ATTENUATION MODELLING UNDER THE BREAKING OF INTERNAL SOLITARY WAVES AND REPRODUCTION OF THE STRATIFIED LAKES WITH HIGH ACCURACY
- 2020, 65, Ⅰ_1267 - 1272, Japaneseマリモにおける弾性定数と粘性係数の推定及びMR解析—ESTIMATION OF ELASTICITY AND VISCOSITY OF MARIMOS AND MR DATA ANALYSIS
When aquatic plants deflect by waves and currents, absorption rate of dissolved inorganic carbon varies dramatically. Therefore, it is necessary to evaluate the effect of wave-current on aquatic plants. In the previous studies, there are significant problems such as not fully considering the interaction between elasticity and currents. In this study, we developed a Submerged Aquatic Vegetation model (SAV model) by including branch and using object-oriented programming that enables to analyze the accurate interaction between wave-current and aquatic plants. As a result, we estimated the values of significant parameters for SAV model from laboratory experiments. Also, Minimum Elastic Modulus of branch (MEM) is revealed to be associated with the length of branch though MEM is not affected by the flow velocity and the position of branch. It was demonstrated that the larger the branch length, the larger the MEM is needed.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 76 (2), I_1075 - I_1080, JapaneseIn recent years, affected by global warming, overturning is suppressed in large lakes such as Lake Biwa and the similar phenomenon is likely to occur in the future. In order to prevent such phenomenon, it is very important to reproduce the stratified lakes with high accuracy. However, the past research based on the hydrostatic pressure approximation did not take the loss of potential energy (𝐸𝑝) into consideration, and the analysis of 𝐸𝑝 is larger than reality. Therefore, this study is focused on internal solitary waves and tries to model the energy loss under hydrostatic pressure approximation. As a result, the energy loss of internal solitary waves can be modelled under hydrostatic pressure approximation successfully by using frictiontype energy loss and highly accurate analysis of the stratified lakes under hydrostatic conditions becomes possible.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 76 (2), I_1399 - I_1404, JapaneseInternal solitary waves are likely to be excited by the external forces such as wind in stratified lakes and coastal areas. When the internal solitary waves break on a slope, potential energy (Ep) of the internal solitary wave tends to be lost completely. The previous studies showed that hypoxia recovers on sloping bottom boundaries in Tokyo Bay when a strong wind is given. However, Ep of internal solitary waves cannot be included in a real-scale simulation because of the hydrostatic pressure approximation. Therefore, this study aims to model the energy loss to take account the breaking of internal solitary waves on a slope. As a result, the energy loss of internal solitary waves can be modeled under hydrostatic pressure approximation successfully by using friction-type energy loss not only in laboratory scale phenomena but also in real scale phenomena, Tokyo Bay.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 76 (2), I_780 - I_785, JapaneseAegagropila linnaei are natural monuments of Japan and in danger of extinction. However, the formation of Marimos has been unresolved. For the clarification of the creation of Aegagropila linnaei, a numerical computation is one of the most powerful techniques, such as a Distinct Element Method (DEM). We attempted to estimate two significant parameters for DEM, elastic modulus and viscosity coefficients of Aegagropila linnaei by applying laboratory experiments, which revealed that two parameters are constant regardless of size and density. Furthermore, we investigated Marimos by using Magnetic Resonance Imaging, which allows non-destructive investigation of Marimos underwater. The base of Marimos is revealed to move from the outer edge to the centre of Aegagropila linnaei when they grow.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 76 (2), I_1267 - I_1272, JapaneseTriangular-shaped surface waves occur with large amplitude in a river during a flood. The large amplitude surface waves are concerned to cause damage to river structures. Higashikawa et al. (2019) found that the train of triangular-shaped surface waves occurs due to soliton resonance. They assumed that the propagation direction of the soliton resonance inclines to the flow direction when the modified Miles' solution is applied. In this study, we aim to derive theoretical solutions by modifying the hypothesis. As a result, our new solutions agree with the laboratory experiment results better than Higashikawa et al. (2019). Furthermore, we confirmed that triangular-shaped surface waves occur due to soliton resonance.
Japan Society of Civil Engineers, 2020, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 76 (2), I_1063 - I_1068, Japanese- Elsevier BV, Jul. 2022, Marine Pollution Bulletin, 180, 113792 - 113792, English
[Refereed]
Scientific journal
We propose a new geophysical flow circulation model (GeoCIRC) based on object-oriented programming to compute surface and ground water flows. In this study, we focus on an infiltration processes and illustrate the basic structure of the model. The computational domain is discretized with vertical column objects that compute vertical infiltration processes within each column. They are horizontally interconnected and compute horizontal infiltration processes. The each column object consists of layer objects of different properties and resolutions to express weather, ground and geological characteristics. As a computational example, vertical circulation due to the horizontal density difference was reproduced. Then, to verify the accuracy of the model, GeoCIRC was applied to river discharge process in the Kushiro River. The computed results showed good agreements with the CoD of 0.95 and 0.81 for the Gojukkoku and Hirosato river discharge stations, respectively.
Japan Society of Civil Engineers, 2015, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 71 (4), I_283 - I_288, JapaneseMany investigations related to soliton resonance with the large initial amplitude of surface waves have been done in the previous studies by using numerical computaions and laboratory experiments. However, less attention has been paid to small intitial amplitude waves in the analysis of soliton resonance. Therefore, this study aims to investigate soliton resonance with the initial amplitude of 10 % of the total water-depth for surface waves by using the fully-nonlinear and strongly-dispersive wave model. As a result, the amplification rate was found to reach to 3.6 times as large as the initial amplitude. Also, the large amplification rate was found to appear when the initial shape of a solitary wave can be modeled by the KdV theory.
Japan Society of Civil Engineers, 2015, PROCEEDINGS OF THE JAPANESE CONFERENCE ON COASTAL ENGINEERING, 71 (2), I_1 - I_6, Japanese- Japan Society of Civil Engineers, 2018, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 74 (4), I_1423 - I_1428
Scientific journal
- Japan Society of Civil Engineers, 2017, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 73 (4), I_1405 - I_1410
Scientific journal
- Elsevier BV, Jan. 2022, Science of The Total Environment, 803, 150044 - 150044
Scientific journal
Field observation and numerical simulation in Tokyo Bay in 2005 and 2007 are performed using TOKYO3D and ELCOM-CAEDYM respectively. It has been observed that fresh water intrusion after the storm event does not disturb stratification in Tokyo Bay, henceforth, artificial mixing should be introduced to eliminate the Oxygen-Deficient Water.
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2008, Proceeding of Annual Conference, 21, 42 - 42, Japanese
MISC
- Feb. 2020, Ocean Science Meeting 2020Source-region identification by adjoint frequency response analysis: an application to low-mode internal tides on the Australian North West Shelf
- Jan. 2020, Water and Environment Technology Conference 2019Mobility and partitioning of heavy metals in the basin of Mellah River, Algeria
- Jul. 2019, AOGS MeetingOccurrence of hypoxia in a reservoir
- 2016, IWA World Water Congress and Exhibition 2016, EnglishInfluence of nutrient and fine sediment control to primary productivity by benthic attached algae in forest watershed
[Refereed]
Introduction international proceedings
- The 7th International Conference on Water Resources and Environment Research, 2016, The 7th International Conference on Water Resources and Environment Research, EnglishClimate Change Impact Assessment on Nutrient Discharge Using Multi-Model and Multi-Scenario of GCMs in Shiretoko
[Refereed]
Introduction international proceedings
- 2016, Libra de articulos del XXVII Congress Latinoamericano de Hydraulica, EnglishOrganic carbon transport during flood due to rainfall in a headwater catchment of Kushiro Wetland, JAPAN
[Refereed]
Introduction international proceedings
- Kyoto University, Apr. 2015, RIMS Kokyuroku, 1946, 87 - 94, JapaneseNumerical solutions and simulations of surface/internal solitary waves
Since marine derived nutrients (MDN) are transported not only in river channels but also across the entire river basin, including via ground water and migratory animals, it is necessary to investigate the contribution of MDN to the forest floor (soils) in order to quantify the true role of MDN at the river ecosystem scale. This study investigated the contribution of pink (Oncorhynchus gorbuscha) and chum salmon (O. keta) to total oceanic nitrogen (TN) input across a river basin using stable isotope analysis (SIA) of nitrogen (δ15N). The contribution of TN entering the river basin by salmon was 23.8 % relative to the total amount of TN exported from the river basin, providing a first estimate of MDN export for a river basin. The contribution of nitrogen from the ocean to the river basin soils was between 22.9 and 23.8 %. Furthermore, SIA showed that the transport of oceanic TN by sea eagles (Haliaeetus spp.) was greater than that by bears (Ursus arctos), which had previously been that bears are thought to be the major animal transporter of nutrients in the northern part of Japan.
Copernicus GmbH, 2015, Biogeosciences Discussions, 12 (7), 5535 - 5557, English- 2014, Proceedings of annual conference, Japan Society of Civil Engineering, Hokkaido Branch, 71, B-44, EnglishIdentification of major suspended sediment sources using X-ray florescense analysis: the Oromushi river basin case of study
Summary national conference
- 2014, Proceedings of annual conference, Japan Society of Civil Engineering, Hokkaido Branch, 70, B-24, EnglishIdentification of dominant suspended sediment sources in a river basin using X-ray florescence analysis
Summary national conference
- Asia Oceania Geosciences Society 2014, 2014, Asia Oceania Geosciences Society 2014, EnglishProjection of Nutrient Discharge by Using Different Bias Correction Method for Precipitation in Shiretoko
[Refereed]
Summary international conference
- 2014, 第27回（2014年度）水文・水資源学会総会研究発表会要旨集, p.100135, Japanese安定同位体比を利用した知床における海陸の栄養循環
Summary national conference
- 2014, 第27回（2014年度）水文・水資源学会総会研究発表会要旨集, p.100094, Japanese湖沼におけるメタン生成量推定手法の検討
Summary national conference
- 2014, 土木学会北海道支部論文報告集, 70, B-46, Japanese地球規模での環境変動が知床の栄養流出に及ぼす影響評価
Summary national conference
- 2014, 土木学会北海道支部論文報告集, 70, B-25, Japaneseラウス川流域におけるリン流出量と還元量の推定
Summary national conference
- Sep. 2013, 国土技術政策総合研究所資料, (752), 16P, Japanese宮古湾における底泥およびアマモのモニタリング結果(2012年10月)
- 2013, 第26回（2013年度）水文・水資源学会総会研究発表会要旨集, 180 - 181, Japanese結氷した湖沼におけるメタン生成過程の解明に向けた現地観測
Summary national conference
- 01 Aug. 2012, 土木学会年次学術講演会講演概要集(CD-ROM), 67th, ROMBUNNO.II-055, Japanese内部ケルビン波の砕波により発生する流れに関する研究
- Kyoto University, Jul. 2012, RIMS Kokyuroku, 1800, 1 - 13, JapaneseNumerical calculation of tsunami generation and propagation considering velocity distribution or density stratification (New Developments in Study of Nonlinear Wave Phenomena)
- 2012, Proceedings of 26th annual conference, Japan Society of Hydrology and Water Resources, 164 - 165, EnglishSediment transportation area-weighted rate evaluation by chemical composition analysis in a river basin, using Oromushi River as case of study
Summary national conference
- 11th International Conference on Civil and Environmental Engineering, 2012, Proceedings of the 11th International Conference on Civil and Environmental Engineering, 89 - 90, EnglishComparison of Water Circulation Mechanisms between the 1970s and the 2000s in Kushiro Wetland
[Refereed]
Introduction international proceedings
- 2012, 第25回（2012年度）水文・水資源学会総会研究発表会要旨集, 82 - 83, JapaneseMRI-AGCM3.1とCMIP3のマルチ気候モデルを利用した東京湾で発生する強風の将来予測
Summary national conference
- 2012, 土木学会北海道支部論文報告集, 68, B-20, Japanese釧路湿原における分布型流出モデルの再現性の検討
Summary national conference
- 2012, 土木学会北海道支部論文報告集, 68, B-59, Japanese知床における海陸の栄養塩循環量の推定
Summary national conference
- 2012, 土木学会北海道支部論文報告集, 68, B-59, Japanese東京湾の生態系モデル開発に向けたパーシャルセルの適用
Summary national conference
- 公益社団法人土木学会北海道支部, 2011, 論文報告集, 23 (68), Japanese異なる成層場における内部ケルビン波の斜面上での砕波
- 2011, Proceedings in the symposium on Extreme Weather and Impact Assessments - for contributing the IPCC AR5 -, 39, EnglishRainfall Analysis in Subtropical Panama
Summary national conference
- 2011, Proceedings in the symposium on Extreme Weather and Impact Assessments - for contributing the IPCC AR5 -, 40, EnglishProjections of Rainfall Intensity in Central America, Panama
Summary national conference
- 2011, 土木学会年次学術講演会報告集, 66, II-195, JapaneseGCMを用いた東京湾におけるDO濃度回復に関する将来予測
Summary national conference
- 2011, 極端気象現象とその気候変動による影響評価に関するシンポジウム（Ⅱ）要旨集, 41, JapaneseGCMを利用した東京湾における強風の将来予測
Summary national conference
- 2011, 第24回（2011年度）水文・水資源学会総会・研究発表会要旨集, P.96, Japanese知床ラウス川からの栄養塩フラックスの推定
Summary national conference
- 2011, 土木学会北海道支部論文報告集, 67, B-22, Japanese知床ラウス川流域における安定同位体比を用いた海起源栄養塩の分布解析
Summary national conference
- 2011, 土木学会北海道支部論文報告集, 67, B-45, JapaneseGCM を用いた東京湾に対する風速の再現性の基礎的検討
Summary national conference
- 2010, 第23回（2010年度）水文・水資源学会総会・研究発表会要旨集, P.141, Japanese知床における安定同位体比を用いた栄養塩循環に関する基礎的検討
Summary national conference
- 2010, 土木学会北海道支部論文報告集, 66, B-38, Japanese安定同位体比を用いた知床における栄養塩循環の基礎的検討
Summary national conference
- 2009, 土木学会北海道支部論文報告集, 65, B-28, Japanese2007年～2008年における網走湖の観測結果について
Summary national conference
- 2009, 土木学会北海道支部論文報告集, 65, B-39, Japanese2006年10月の洪水時における網走湖内の流動解析
Summary national conference
- 2008, 第21回（2008年度）水文・水資源学会総会・研究発表会要旨集, P.85, Japanese網走湖を対象とした風応力の内部ケルビン波と物質循環への影響評価
Summary national conference
夏季における東京湾の湾央から湾奥にかけて，底層での有機物の分解に伴う酸素消費によって，底層に貧酸素水塊が発生することが良く知られており，この貧酸素水塊は，東京湾における生態系，水質環境に大きな影響を及ぼしていることから，どのようなメカニズムで底層の溶存酸素（DO）濃度が変化しているかを把握することは重要である．通常，夏季におけるエスチュアリー循環での湾内水の湾外水との交換は20日から30日であり，河川出水が生じると交換がより促進されることが知られている．そのため，河川出水が生じるとDO濃度が大きく回復する可能性がある．そこで本研究では，まず湾央の底層におけるDO濃度に着目し，河川出水イベントによる影響評価手法確率のためのDO濃度再現モデルの作成を行うことを目的とした．その結果，観測地点におけるDO濃度は，河川流入によるエスチュアリー循環の変化によって大きく変動していることが確認された．
THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, 2006, Proceeding of Annual Conference, 19 (0), 65 - 65- 国土技術政策総合研究所, Jun. 2003, 国土技術政策総合研究所資料, (87), 1 - 23,巻頭1〜3, Japanese荒川河口域における混合形態に伴うChlorophyll-α動態と海域への河川流入負荷量変動
- 国土技術政策総合研究所, Dec. 2001, 国土技術政策総合研究所研究報告, (1), 1 - 3,1〜16, Japanese環境施策に資する内湾域の総合的な環境把握を目指したMEL1D-MBモデルの構築
- 公益社団法人 日本水道協会, 2020, 全国会議（水道研究発表会）講演集, 2020, 174 - 175, Japanese
- 京都大学, Aug. 2010, 数理解析研究所講究録, 1701, 206 - 211, Japanese潜堤上における非線形内部波の伝播特性 (非線形波動現象の数理と応用)
- 2021, 土木学会北海道支部論文報告集(CD-ROM), (77)Characterization of rare earth elements in terrestrial water and biological samples in the east Hokkaido
- 2018, 土木学会関西支部年次学術講演会講演概要集(CD-ROM), 2018外的要因が球状マリモ形成に与える影響評価のための固液混相流モデルの開発
- 2016, 土木学会年次学術講演会講演概要集(CD-ROM), 71st阿寒湖におけるマリモ球状化に影響を与える風の将来予測
- 2020, 土木学会論文集 B2(海岸工学)(Web), 76 (2)DEVELOPMENT OF SUBMERGED AQUATIC VEGETATION MODEL CONSIDERING BRANCH
- 2020, 土木学会論文集 B1(水工学)(Web), 76 (2)ENERGY ATTENUATION MODELLING UNDER THE BREAKING OF INTERNAL SOLITARY WAVES AND REPRODUCTION OF THE STRATIFIED LAKES WITH HIGH ACCURACY
- 2015, 土木学会年次学術講演会講演概要集(CD-ROM), 70th釧路川流域における湿原再生に向けた栄養塩輸送量の評価手法に関する研究
- 2014, 土木学会北海道支部論文報告集(CD-ROM), (70)内部ケルビン波の砕波により誘起される水平循環
- 2014, 土木学会北海道支部論文報告集(CD-ROM), (70)東京湾の水質予測に与える干潟の影響
- 2012, 水工学論文集(CD-ROM), 56環境流体解析のための簡易Wetting and Dryingスキーム
- 2012, 土木学会北海道支部論文報告集(CD-ROM), (68)Partial Cellを導入した塩水遡上解析
- 2011, 水工学論文集(CD-ROM), 55海面上昇を考慮した釧路湿原への塩水遡上の影響評価
- 2010, 土木学会北海道支部論文報告集(CD-ROM), (66)網走川において風波が塩水浸入に及ぼす影響評価
- 2010, 土木学会北海道支部論文報告集(CD-ROM), (66)コリオリを考慮した斜面上での内部波の砕波について
Books etc
- Others, 北海道大学出版会, Apr. 2017, Japanese湿地の科学と暮らし－北のウェットランド大全
Scholarly book
- Others, 朝倉書店, Feb. 2017, Japanese地形の辞典
Scholarly book
- Others, 朝倉書店, Apr. 2013, Japanese図説日本の海岸
Scholarly book
- Others, Springer, Apr. 2006, EnglishThe Environment in Asia Pacific Harbors
Scholarly book