Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)
Online ISSN : 2185-467X
ISSN-L : 2185-467X
Volume 74, Issue 3
Displaying 1-4 of 4 articles from this issue
Paper (In Japanese)
  • Shinya ITOSHIRO, Masazumi AMAKATA, Shuji TAKAMORI, Takanobu SHIMADA, N ...
    2018 Volume 74 Issue 3 Pages 44-61
    Published: 2018
    Released on J-STAGE: September 20, 2018
    JOURNAL FREE ACCESS
     Maintaining and improving whole Japan’s productivity is big challenge for us under the situation such as climate change and depopulation. One possible countermeasure is urban restructuring with economically and socially low flood damage risk. This study aims to analyze simultaneous flood risk with multiple rivers and drainage system in an urban area, to understand urban structure more clearly in relation to flood risk, and to find out the direction of new flood control management in cooperation with urban planning. The analysis applied to Toyama City which pro motes compact city strategy gives us a result of the possibility that the limitation of area to be reduced inundation depth and location optimization of urban facilities are more effective than complete flood control with continuous embankment. In addition, this study shows the feasibility of efficient flood control management considering the change of population distribution and flood risk and cost reduction in cooperation with the induction countermeasures of urban structure such as regulation, subsidy an d recognition of risk.
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  • Hiroyuki SUZUKI, Tatsuhiko ISHIDA, Daisuke IKEDA
    2018 Volume 74 Issue 3 Pages 62-69
    Published: 2018
    Released on J-STAGE: October 20, 2018
    JOURNAL FREE ACCESS
     Henry's formula and Toch's formula are most often used to estimate an outflow from sluice gate. But, a change of flow that occur in the transverse direction is not considered in the Henry's formula and Toch's formula. Generally, in an actual river, multiple sluice gates are constructed in the transverse direction of a river. A flow from a multiple sluice gates have a change that occur in the transverse direction. Therefore, Henry's formula and Toch's formula cannot estimate an outflow from a multiple sluice gates.
     This paper discussed the new estimation method of outflow from a multiple sluice gates in the case of central gate operated. This study induced a new formula based on the Henry's theory considering a diffusion of jets from a central gate. As a further problem, a method of classification between free efflux and submerged efflux have not been existed until now. This study indicate a classification method. The classification method is based on that the momentum of jets is equal to the momentum of flow which is formed by diffusion of jets. In this paper, an effect of the new formula and classification method was clarified by an experiment.
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  • Hiroyuki SUZUKI, Koudai KAJITA, Nao MUKAI, Daisuke IKEDA
    2018 Volume 74 Issue 3 Pages 70-82
    Published: 2018
    Released on J-STAGE: October 20, 2018
    JOURNAL FREE ACCESS
     Past studies indicated that the outflow from a small capacity dam in a large flood period was greatly underestimated. This is because the approach velocity head was not taken into consideration in the calculation of outflow from the dam. However, the process by which approach velocity is generated has not been investigated in past studies. In this study, the process by which approach velocity is generated was investigated by 3D simulation targeting a small capacity dam reservoir in which the occurrence of approach velocity was confirmed in a past study. Furthermore, in this study, the condition in which approach velocity is generated and the influence of approach velocity on outflow estimation were investigated by an experiment on flow on a weir. When the overflow depth is larger than the height of the weir, it was shown that approach velocity becomes so large that it cannot be ignored when calculating outflow.
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Technical Report (In Japanese)
  • Shingo SATOMURA, Junichi SUTOU, Katsuo ITOU, Ryousuke HIRAIDE, Takeshi ...
    2018 Volume 74 Issue 3 Pages 83-94
    Published: 2018
    Released on J-STAGE: December 20, 2018
    JOURNAL FREE ACCESS
     One third of the area of Joso City suffered flooding due to the Kanto-Tohoku torrential rain. Numerous delays and isolation of evacuation occurred in the flood. We developed a planning process of My-TimeLine with the aim of allowing each resident to grasp information, judgments and actions necessary for evacuation and to have suitable evacuation methods. When developing the methods, in cooperation with 165 Joso-City residents at the committees, we created My-TimeLine through a social experiment. From the questionnaire response results of the residents, the knowledge and preparation of flood risk were shared by the residents during the consideration process of the My-TimeLine. In conclusion, we showed that residents themselves could organize and prepare in advance the actions for disaster prevention such as evacuation.
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