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| | Abstract | | An artificial groundwater infiltration test was conducted in Nagaoka City in Japan, and time-lapse cross-borehole GPR data were collected to monitor the infiltration process in the vadose zone using zero-offset profiling,ZOP, mode. The downward migration of induced water was observed as a variation of GPR traveltimes, which can be transformed into dielectric constant and further converted to volumetric water content. We present an effective approach to extract accurate information about the hydrogeologic process in the vadose zone from ZOP data. This approach is based on a least-squares inversion method using singular value decomposition,SVD, in which a finite-difference time-domain forward modeling is used for computing electromagnetic wave fields on two-dimensional cylindrical coordinates. We can successfully estimate the variation of soil water content during infiltration in the Nagaoka site from the reconstructed dielectric constant models. The inversion results show that the saturation information is useful to assess hydrogeologic properties of the test soil zone. |
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