Development of new imaging method of hydraulic conductivity structure

对地下水流动模式的认识是科学、工程和农业领域的重大课题。我们关注的是地表的自电位（自然电位），它可以通过地下水流动产生。在本研究中，我们开发了用于计算地下水流量和自势分布的数值正演代码。利用水工构筑物的自势数据，构造了水工构筑物的反演格式。数值可行性研究有力地证明了地下水力非均质成像的可能性。在此基础上，采用数值方法对实际场电位数据进行了分析。结果，我们成功地从自势数据中得到了合理的水工结构。我们提出的自势分析新方案将有助于理解地下流体的流动。

Understanding of groundwater flow pattern is big issue in science, engineering and agriculture. We focus on the self potential (natural electrical potential) on the surface, which can be generated by groundwater flow. In this study, we developed the numerical forward codes for calculations of the groundwater flow and self-potential distributions. An inverse scheme of hydraulic structure by using the self-potential data is also constructed. The numerical feasibility studies strongly suggested the possibility to image the subsurface hydraulic heterogeneity. Then, we adopted our numerical technique for analyzing the real field data of self-potential. As a result, we succeed in getting a reasonable hydraulic structures from the self-potential data. Our new scheme for analysis of self-potential will be helpful for understanding the subsurface fluid flow.