Aquifer classification and pneumatic diffusivity estimation using periodic groundwater level changes induced by barometric pressure

• Yang Heejun

  Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, Japan

• Shibata Tomo

  Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, Japan

抄録

To classify the aquifer type and to estimate the pneumatic diffusivity using harmonic analysis and analytical expressions, we measured groundwater levels and barometric pressure in an unconfined aquifer with a thick unsaturated zone at a southern part of the Beppu volcanic fan, Japan. The groundwater level was inversely related to the barometric pressure, with little or no time lag behind barometric pressure. The groundwater level and barometric pressure exhibit periodic changes with prominent spectra at K₁ (lunar-solar diurnal) and S₂ (main solar semidiurnal) tidal constituents but not at O₁ (main lunar diurnal) and M₂ (main lunar semidiurnal) tidal constituents, which are the motions of solar and lunar relative to the earth. It indicates that the aquifer is an unconfined aquifer type with no earth tide effect. Pneumatic diffusivity in the unsaturated zone was estimated as 7.6 × 10^–2 to 5.7 × 10^–3 m²/s using changes between the groundwater level and the barometric pressure. The pneumatic diffusivity and the unsaturated zone thickness strongly affect amplitude ratios and phase lags between the groundwater level and the barometric pressure in the unconfined aquifer.

収録刊行物

• Hydrological Research Letters

  Hydrological Research Letters 14 (3), 111-116, 2020

  水文・水資源学会／日本地下水学会／日本水文科学会／陸水物理研究会

キーワード

• Earth and Planetary Sciences (miscellaneous)
• Water Science and Technology

詳細情報

• CRID: 1390567172566075776
• NII論文ID: 130007896212
• DOI: 10.3178/hrl.14.111
• ISSN: 18823416
• Web Site: https://www.jstage.jst.go.jp/article/hrl/14/3/14_111/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可