琉球石灰岩洞くつの空間分布特性

DOI

書誌事項

タイトル別名
  • Characteristics of Spatial Distribution of Caves in Ryukyu Limestone in Southern Part of Okinawa Island
  • 米須地下ダム流域を例として

抄録

The caves in Ryukyu limestone which are estimated from boring data in Komes groundwater basin, southern part of Okinawa island, are distributed within 500 m in distance from sea shore and in range of 10 m--50 m in altitude. Palaeo-gradients of shallow groundwater tables, which are presumed from linear arrangements of caves in direction from sea shore to inland show 1/20→1/40→1/60→1/70 in ascending order. The palaeo-gradients have gentler slope toward upper level. However, the palaeo-gradients are too steep compared with recent groundwater gradient around sea shore that has a gradient of 1/300-1/500. The continuous tilting of basement may be caused the steep palaeo-gradient of groundwater. The construction ages of cave estimated from palaeo-sea level corrected tilting and sea level curve are presumed as follows: minimum level:-45m, 9800-8300 years B.C.;-31m, 7600 year B.C.;-15m, 5800 years B.C.;-2m, 4300 years B.C.; +4m, 2800 years B.C. in ascending order. Permeability of Ryukyu limestone estimated from a relationship between distance from seashore and amplitude of groundwater table is 0.0006m/s. Permeability estimated from a delay time of phase difference of groundwater from tide level is 0.008 m/s. The reason for higher permeability estimated from delay time from tide level is considered that the permeability may be an apparent permeability, because a phase difference of groundwater table from tide level is caused by a propagation of tide pressure without movement of groundwater flow.

収録刊行物

キーワード

詳細情報 詳細情報について

  • CRID
    1390282679520048512
  • NII論文ID
    130004118975
  • DOI
    10.11408/jsidre1965.2002.89
  • ISSN
    18847234
    03872335
  • データソース種別
    • JaLC
    • CiNii Articles
  • 抄録ライセンスフラグ
    使用不可

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