Near surface geophysics

[NS-01] Proposed a survey system to clarify the distribution and flow model of high-salinity groundwater by resistivity exploration and geological survey

*Nariaki Nishiyama¹, Koichi Suzuki², Kazuhiro Tanaka³, Masahiro Chigira⁴ (1. Ospec Inc. (Japan), 2. Hokkaido Univ. (Japan), 3. Yamaguchi Univ. (Japan), 4. Fukada Geological Inst. (Japan))

The distribution and flow model of high-salinity groundwater are important information in various fields such as geological disposal, CO₂ geological storage, and hot spring resources. As a method of obtaining the distribution of high-salinity groundwater over a wide area, there are electrical exploration methods and electromagnetic exploration methods that can non-destructively visualize the resistivity distribution from the ground surface, and examples of visualizing the fresh-salt interface near the coast. However, there are few studies on the distribution and flow model of high-salinity groundwater on land, and most hybrid studies using geophysical exploration have been made based on the geological information of the flow field and the groundwater itself. In this study, the distribution and flow model of high-salinity groundwater based on the results of groundwater surveys, electromagnetic surveys, and geological structure surveys at three sites (Tokusa, Higashi-kubiki, and Yuda). Furthermore, based on the results of these studies, we proposed a survey method for clarifying the distribution and flow model of high salinity groundwater. Research results on the distribution and flow model of high-salinity groundwater at the three sites using these methods will contribute to the groundwater flow modeling that gives a bird's-eye view of the entire region, and to provide us with important basic information for underground use.