| 講演要旨(和文) | | 筆者らは河道内や浅海域でも適用可能な水域浅部物理探査技術の開発と実用化を進めている．その一環として，湛水期には水没し，渇水期には高水敷となる河川堤外地において，湛水期に展開した測線と同じ位置で統合物理探査を実施した．その結果水面より上部となった不飽和表層を除き，S波速度構造，比抵抗構造とも湛水期と調和的な結果を得ることができた． |
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| | 講演要旨(英文) | | We have proposed a novel method to apply integrated near surface geophysical investigation in water covered areas. The major components of the method are under-water hybrid surface wave method and under-water DC resistivity method. To certify the method and to examine its field measurement parameters, we conducted a preliminary study in a river stream. As a result, 2D Vs and resistivity structure was clearly delineated up to 40 m below the river bottom. Regretfully, reference information was very limited. We therefore conducted comparative measurements on the same line deployed on a river bed but under the dry condition. Capacitively coupled resistivity survey using OhmMapper, hybrid surface wave surveys including walk-around surface wave method, and GPR were adopted to obtain the reference data. As a result, 2D Vs structure along the survey line was successfully delineated up to 40 m deep, and resistivity structure of the superficial 10 m in depths. Both structures were basically similar to those obtained by the preliminary study or water-covered condition except for the superficial zone about 2 m in depths or above the groundwater level. |
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