Abstract
We evaluated the symmetry of theoretical and experimental analysis of water contamination such as non-aqueous phase liquid (NAPL) by using amplitude variations with offset analysis (AVO) of ground-penetrating radar (GPR) data. We used both theoretical and experimental approaches for AVO responses of GPR to small distributions of contamination. Theoretical modeling is a tool used to confirm the feasibility of geophysical surveys. Theoretical modeling of NAPL-contaminated sites containing wet sand—both with the water and light non-aqueous phase liquid—was applied by keeping in consideration the GPR AVO analysis in acquisition. Reflectivity was significantly altered with the changes in the contents of water and NAPL during modeling. The wet and dry sands introduced in our model changed two major phenomena: one, the wave pattern—implying a slight phase shift in the wave; and two, an amplitude jump with the dim reflection radar gram observed in the model. Experimental data were collected and analyzed; two observations were recorded during physical data analysis. First, relative permittivity confirmed the presence of NAPL in an experimental tank. Second, reflection patterns with jumps in amplitude and changes in polarity confirmed the theoretical investigation. Our results demonstrate that GPR AVO analysis can be as effective for detection of non-aqueous phase liquid (NAPLs) as it has been used to determine moisture contents in the past. The theoretical and experimental models were in symmetry, and both found a jump in reflection strength. The reflection pattern normally jumped with NAPL-intrusion. From the perspective of water contamination, this study emphasizes the need to take into account the impact of GPR AVO analyses along with the expert’s adaptive capacities.
Highlights
Non-aqueous phase liquids (NAPLs) come in two types: light non-aqueous phase liquids (LNAPL)that are less dense than water and tend to float on the water table; and dense non-aqueous phaseSymmetry 2020, 12, 991; doi:10.3390/sym12060991 www.mdpi.com/journal/symmetrySymmetry 2020, 12, 991 liquids (DNAPL) that are denser than water and tend to sink through the saturated zone until they encounter a low permeability layer
According to principle of electromagnetic wave Propagation, electromagnetic field vector is divided into transverse magnetic (TM) wave and transverse electric (TE) wave, the electric field component is perpendicular to incident plane, while the magnetic field component is perpendicular to the plane of incidence [8]
The present study documented the model of a control signal processing of the theoretical and Thedetection present study documented the model of aofcontrol signal processing the theoretical and physical of water contamination
Summary
Non-aqueous phase liquids (NAPLs) come in two types: light non-aqueous phase liquids (LNAPL)that are less dense than water and tend to float on the water table; and dense non-aqueous phaseSymmetry 2020, 12, 991; doi:10.3390/sym12060991 www.mdpi.com/journal/symmetrySymmetry 2020, 12, 991 liquids (DNAPL) that are denser than water and tend to sink through the saturated zone until they encounter a low permeability layer. All NAPLs are low permittivity because they are nonpolar fluids and have low conductivity. A free-phase NAPL remains low-conductivity and low-permittivity. Depending on the design and polarization of an antenna, there is significant angle-dependent radiation, perhaps one of the more challenging aspects of GPR AVO because it depends on near field electrical properties. GPR AVO analysis is a convenient—and stronger—method for NAPL detection in the subsurface than conventional GPR methods existing in previous studies, as confirmed by subsequent findings of [3]. These models indicated that the presence of NAPL produces both amplitude and phase anomalies. The inclusion of phase anomaly analysis requires modification of the existing
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