Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
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Volume 51, Issue 3
Displaying 1-4 of 4 articles from this issue
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Original Article
  • Change of Chemical Composition of Aqueous Solution and Factors Controlling pH in Interaction of Water and Sedimentary Rock from Horonobe Area, Hokkaido
    Naotatsu SHIKAZONO, Naoki YOSHIDA, Masataka NAKATA
    2010 Volume 51 Issue 3 Pages 112-121
    Published: 2010
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.51.112
    JOURNAL FREE ACCESS
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     Water-rock interaction experiments were performed using drill-core samples (diatomaceous mudstone, hardshale) from Horonobe area, Hokkaido. Experimental results show that the pH of alkaline (initial pH=9) and acidic(initial pH=5) solutions neutralized very rapidly at initial stage and subsequently pH decreased gradually. The decrease in pH is caused by the oxidation reaction of pyrite. The ratio of H+ to SO42- (H+/SO42-) which were produced by the oxidation reaction of pyrite did not accord with the analytical results which show the lower ratio (H+/SO42-=0.04 (mudstone), 0.005 (shale)). This indicates that most of H+ generated by pyrite oxidation in the experiments was consumed. The consumption of H+ by H+-cation (alkali and alkali earth ions) exchange reaction and dissolution of feldspar can explain this difference.
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Report
  • Morphological Features of Tafoni on Paleogene Sandstone Cliff in Amakusa Kami-Island, Kumamoto Prefecture, Kyushu, Japan
    Ken-ichi NISHIYAMA, Shuichiro YOKOTA
    2010 Volume 51 Issue 3 Pages 122-129
    Published: 2010
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.51.122
    JOURNAL FREE ACCESS
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     Morpholological features of tafoni have been studied, which are well developed on sandstone cliff in the Amakusa Kami-Island, Kumamoto, Kyushu, Japan. Numerous tafoni were observed on rock surface of sandstone not only in coastal zone, but also inland mountainous zone. Rock meal fallen from concave roofs of tafoni indicates that tafoni have grown continuously. Lowest value in rock hardness on the concave roof surfaces support that tafoni has been formed with high decreasing rate of rock strength. This means that the growth of tafoni may also be closely related to salt weathering.
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  • Evaluation of Sustainable Groundwater Development Potential, Case Study on the Groundwater Irrigation Project in Eastern Indonesia
    Takuya YOSHIZAWA
    2010 Volume 51 Issue 3 Pages 130-139
    Published: 2010
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.51.130
    JOURNAL FREE ACCESS
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     Recently issues on water resources are highlighted because, especially in developing countries, water demand has been increasing as population growth and involved food production growth. Preservation of groundwater resources are needed as a valuable fresh water resource in the world. Japanese government has been engaging to support such water resources issues with providing official development assistance schemes for water shortage area in south-eastern Asia and Africa. Sustainability is very important to implement development project successfully. The area with insufficient groundwater development potential has been selected as project areas and evaluation of sustainability of groundwater development planning becomes important for the project. This paper describes results of groundwater development study in eastern Indonesia. Groundwater recharge evaluation is carefully introduced to define the amount of discharge of wells in the project. Saline water intrusion is also considered on the study.
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Short Report
  • The Damage in Taiwan Caused by Typhoon No. 8(Morakot)
    —Cases in Xiaolin Cun and Shenmu Cun—
    Ryohei IMAMURA, Akito NAKASUJI
    2010 Volume 51 Issue 3 Pages 140-145
    Published: 2010
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.51.140
    JOURNAL FREE ACCESS
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     Typhoon No.8 (Morakot) that hit the middle-southern part of Taiwan on August 6-11, 2009 caused a large number of deaths and flooding there before it passed by. The most severe damage occurred in two Provinces of Xiaolin Cun and Shenmu Cun, in Kaohsiung County and Nantou cunty respectively. In Xiaolin-Cun the flooding triggered by the heavy rainfall swept away an elementary school.
     It is not doubt that violent downpour whose probability of the same scale of rainfall is one in 200 years became the immediate cause of the floods and debris disasters.
     The region's vulnerability to those calamities however was due to the colluvium layers which thickly cover a wide area of the mountainslopes and to the geomorphological characteristics of the terrain, at which the devastated villages and the elementary school were located on low terraces at a relative height of 5m above the recent riverbed.
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