Numerical Simulation of Groundwater Pollution Model by GPR

With the rapid exploitation and utilization, groundwater pollution increased gradually. Unlike surface water, it would be difficult to recover by self-purification capacity once contaminated. And the trend of pollution is spread from point to plane and shallow to deep, suggesting the increased degree of pollution. Thus, to investigate the degree of pollution is important in using groundwater and preventing contamination. Because different depths and different pollutants can draw distinctive characteristic on the sync-phase axis, Ground Penetrating Radar (GPR) would be an effective way to study groundwater pollution.

Here, we carried out the forward numerical simulation of GPR by finite difference time domain method using GprMax developed by Dr. Antonis. We established 5 models based on the types of groundwater pollution, including different depths, electrical conductivity and permittivity. Then obtained the anomaly characteristics and anomaly patterns of GPR profiles. Our models showed that (1) GPR can distinguish vadose zone and aquifer layer clearly. (2) In the shallow pollution, the anomaly of sync-phase axis is more obvious on upper interface than that on lower interface, indicating that GPR can detect the upper interface of pollution. In addition, low permittivity and low conductivity pollution is easier to be detected than high permittivity and high conductivity on lower interface of pollution. (3) In the deep pollution, both upper and lower interface of low permittivity and low conductivity pollutants can be showed clearly; however, lower interface of high permittivity and high conductivity pollution can hardly be reflected. Therefore, the upper and lower interfaces of low permittivity and low conductivity pollution can be detected by GPR, and high permittivity and high conductivity pollutions can only show its upper interface in the GPR profiles. As a result, GPR is effective in detecting the upper interface of groundwater pollution.