Non-destructive measurements of unsaturated seepage flow using surface ground-penetrating radar

Surface ground-penetrating radar (GPR) was assessed as a non-destructive method to measure the temporal and spatial variability of unsaturated seepage flow under uniform wetting conditions on a homogeneous sandy soil. GPR profile survey with 400MHz antenna was conducted. GPR reflected wave from advancing wetting front during uniform field infiltration experiments was used to map the wetting front depth variability with time. The dielectric constant of soil measured by vertical soil moisture probe below the ground surface was used as standard measures of soil moisture to compare with the GPR estimated unsaturated seepage flow behavior. The utility of our proposed GPR profile survey was demonstrated by using numerical seepage flow FEM analysis of field infiltration experiments. There was good agreement between computed and measured wetted zone movements in two-dimensional unsaturated seepage flow. Traceability of the wetting front depth variability with time was found by GPR profile survey.