Simulation of ground-penetrating radar waves in a 2-D soil model

We have developed a pseudospectral forward modeling algorithm for ground-penetrating radar (GPR) based on an explicit solution of the 2-D lossy electromagnetic wave equation. Complex soil structures can be accommodated with heterogeneous spatial distributions of both wave velocity and electrical conductivity. This algorithm uses a Gaussian line source with uniform directivity, and there are conductive buffer regions surrounding the soil model to approximate absorbing boundary conditions. Three soil models are used to illustrate different aspects of radar wave propagation. The first model is lossless with homogeneous layers imbedded in a homogeneous background medium, the second model has the same lossless layers in a lossy background medium, and the third model is lossless and uses a nonsaturated water flow simulation to create a complex spatial velocity distribution. Two separate simulations with different source frequencies are presented for each soil model. Results indicate that higher frequency GPR will produce a sharper wavelet and can map soil layering structures with high resolution. In a conductive soil, however, higher frequencies attenuate more rapidly and the radar may not detect deeper layers.