Journal of Groundwater Hydrology
Online ISSN : 2185-5943
Print ISSN : 0913-4182
ISSN-L : 0913-4182
Current issue
Displaying 1-13 of 13 articles from this issue
PREFACE
SPECIAL ISSUE: The behavior of groundwater and subsurface fluid on underground space utilization
TECHNICAL REPORTS
REVIEW
PAPER
  • Kei NAKAGAWA, Hidemichi FUJII
    2022 Volume 64 Issue 1 Pages 91-100
    Published: February 28, 2022
    Released on J-STAGE: May 22, 2022
    JOURNAL FREE ACCESS

    Nitrate-nitrogen contamination of groundwater in Shimabara Peninsula continues to be a serious problem. In 2006, Nagasaki Prefecture established the Shimabara Peninsula Nitrogen Load Reduction Plan, and measures have been taken. In this study, we conducted a factor decomposition analysis of the nitrogen load potential using the open data attached to the plan and the data published by the local government and examined what factors have been changing the potential. The changes in nitrogen supply from agriculture, livestock industry, and household life were decomposed into (1) nitrogen intensity factors, (2) structural change factors, and (3) scale factors, and the effects of each factor were quantitatively investigated. Consequently, it was found that the total of the three sectors during FY2013-2019 showed a slight improvement trend, and this was due to the structural change factor in the livestock industry and the cropped area factor in agriculture. Thus, the slight decrease in nitrogen supply during this period is mainly due to the conversion to smaller nitrogen-supplying animals in the livestock industry and the decrease in cropped area in agriculture.

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SHORT NOTE
  • Masaatsu AICHI
    2022 Volume 64 Issue 1 Pages 101-114
    Published: February 28, 2022
    Released on J-STAGE: May 22, 2022
    JOURNAL FREE ACCESS

    Although the regional land surface displacement data observed by Interferometric Synthetic Aperture Radar is expected to contribute to the effective calibration of land subsidence models, the land subsidence models cannot always reproduce the observed data or the inversion analysis possibly estimate a wrong parameter set because the observed data often contains the displacement components caused by unknown processes such as tectonic movement which are not considered in the land subsidence model. This study proposes the minimization of the entropy in terms of the total rotational energy of the residual between the calculated displacement and the observed displacement instead of minimizing the residual itself in the inversion analysis. A preliminary numerical experiment has shown that the proposed method successfully separates the regional displacement components caused by unknown processes and finds the optimal parameter set for the land subsidence model.

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