地下水利用型地中熱利用の導入可能性評価の試み : 遮水層の連続性と地下水水質に関する検討  [in Japanese] An Attempt of Installation Potential Assessment on Groundwater Heat Pumps : Studies on Continuity of Impermeable Layers and Groundwater Chemistry  [in Japanese]

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Abstract

地下水利用型地中熱利用の導入可能性を評価するために, 扇状地地域である岐阜県岐阜市の地質・地下水情報を用いて, 遮水層の連続性と地下水水質の検討を行った. 前者のためには, ケイソウ化石による堆積環境の推定と揚水に伴う帯水層の水位変動の測定を行った. その結果, ケイソウ化石は淡水生であり, 遮水層は後背湿地で堆積し, 地層の連続性は悪いと推定される. また, 遮水層の上下にある2層の帯水層が水位変動の測定から水理的には連結していることが認められた. 後者では, 市街地地域を中心に溶存成分の少ない地下水が分布することが確認された. 遊離炭酸濃度は基準値を超える地域が多いものの, 地下水利用空調機器の利用状況を加味すると, およそ<10mg/Lであれば利用可能であるとみなすことができる. このように, 遮水層が連続しないことから地下水利用型地中熱利用のために揚水してもその影響は一帯水層に集中しないこと, 地下水水質の面からは地下水をヒートポンプ等に直接導入できるような良好な水質を有する地域が多いことが確認できた.

 The continuity of impermeable layers and groundwater chemistry are studied using geological and hydrological information in Gifu city to assess installation potential of groundwater heat pumps. For former study, an estimation of sedimentation environment by diatom fossils and a measurement of water level change by groundwater pumping-up are performed. Extracted diatom fossils are composed of the fresh water assemblage, and suggest that the formation with these fossils was sedimented at the back marsh and its continuity is not good. The measurement result of groundwater level change shows that two aquifers above and under the impermeable layer are connected hydrologically. The latter study revealed that the groundwater with low dissolved contents is widely spread in the urban area of Gifu city. Although the contents of free carbon dioxide are higher than the recommended value in most areas, approximate <10mg/L of free carbon dioxide is assumed to be possible to utilize of groundwater heat pumps based on the present utilization situation. The result of continuity of impermeable layers shows that the influences of groundwater pumping-up for heat pumps are not concentrated into one aquifer due to aquifer connection. Groundwater chemistry reveals that the groundwater can be directly used in the heat pumps due to their low resolved contents.

Journal

  • Journal of the Japan Society of Engineering Geology

    Journal of the Japan Society of Engineering Geology 51(6), 257-264, 2011-02-10

    Japan Society of Engineering Geology

References:  17

Cited by:  1

Codes

  • NII Article ID (NAID)
    10027415015
  • NII NACSIS-CAT ID (NCID)
    AN00026635
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    02867737
  • NDL Article ID
    11004339
  • NDL Source Classification
    ZM49(科学技術--地球科学--地質)
  • NDL Call No.
    Z15-263
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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