Journal of the Japan Society of Erosion Control Engineering
Online ISSN : 2187-4654
Print ISSN : 0286-8385
ISSN-L : 0286-8385
Volume 34 , Issue 1
Showing 1-6 articles out of 6 articles from the selected issue
  • 1981 Volume 34 Issue 1 Pages 1-41
    Published: June 20, 1981
    Released: April 30, 2010
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  • Hiroshi Omura
    1981 Volume 34 Issue 1 Pages 42-52
    Published: June 20, 1981
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    It is necessary to estimate the resistance index, that is the shape parameter in the gamma distribution model, in order to forcast area of landslides in the objective zone. Especially geology in various factors that participate in the resistance index is concerned in this study.
    Total precipitation and landslide area ratio are measured at the 1km2 circular plots, that are set at the center on aero-photographs of eight regions ex. Fujioka region where many landslides have occured by heavy rain.
    The resistance index maps on these regions are drawn by substitution above measured values at each plot into the gamma distribution model. It is obtained by overlay method that the feature of pattern in these maps is closely similar to that in the corresponding geological map.
    As a result of this comparison, the resistance index on each rock and stratum in study area is as follows.
    Fujioka region: Biotite granite <Hornblende biotite granite <Granodiorite <Shistose hornb. biot. granite <Aplite granite <Seto group.
    R. Niyodo region: Suzaki formation <Hayama formation <Zohoin group <Ichinose group <Kamiyakawa formation <Shirakidani formation <Ino formation.
    Yamakita region: Conglomerate <Mudstone <Greentuff <Volcanic conglomerate.
    The resistance index of biotite granite and new formation are generally less than old formation in consolidification. Then the relation between the resistance index C and absolute year of sedimentary rock is given by the next equation, C=κT0.3 where k is the coefficient dependent on the character of region.
    Though an objective area is composed of various rocks and stratums complexly, the relation between total precipitation and landslide area ratio is divided into the next case by the combination of rainfall distribution and resistance index distribution corresponding geological condition.
    In the case of the right angle inter section of isohyet and isopleth on the resistance index map, the landslide area ratio is given by a theoretical curve under the mean resistance index at the objective area. But there is some local deviation by geological condition in the same precipitation.
    On the contrary, in the case of approximately paralell aligment, landslide area ratio is shown by some theoretical curves under the each resistance index that differs according to geological condition with precipitation class.
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese]
    1981 Volume 34 Issue 1 Pages 53-61
    Published: June 20, 1981
    Released: April 30, 2010
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  • [in Japanese]
    1981 Volume 34 Issue 1 Pages 62-64
    Published: June 20, 1981
    Released: April 30, 2010
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  • [in Japanese]
    1981 Volume 34 Issue 1 Pages 65-70
    Published: June 20, 1981
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • 1981 Volume 34 Issue 1 Pages 71-75
    Published: June 20, 1981
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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