High-frequency electromagnetic (EM) surveys have 5 shown to be valuable techniques in the study of soil water content 6 due to the strong dependence of soil dielectric permittivity with 7 moisture content. This quantity can be determined by analyzing 8 the average value of the early-time instantaneous amplitude of 9 ground-penetrating radar (GPR) traces. We demonstrate the re10 liability of this approach to evaluate the shallow soil water content 11 variations from standard fixed-offset GPR data by simulating the 12 data over different likely EMsoil conditions. A linear dipolemodel 13 that uses a thin-wire approximation is assumed for the transmit14 ting and receiving antennas. The homogenous half-space model is 15 used to calculate the waveform instantaneous amplitude values av16 eraged over different time windows.We analyzed their correlation 17 with the soil surface dielectric parameters, and we found a clear 18 inverse linear dependence on the permittivity values. Moreover, 19 we evaluated how different kinds of noise affect this correlation, 20 and we determined the influence of the electrical conductivity on 21 the trace attributes. Finally, through a two-layered medium, we 22 estimated the effect on the GPR signal of a shallow reflector, we 23 analyzed how its presence can carry out inaccuracies in the soil 24 surface dielectric permittivity estimation, and we determine the 25 best time window to minimize these errors.
Di, M., Pettinelli, E., Slob, E. (2013). Early-Time GPR Signal Attributes to Estimate Soil Dielectric Permittivity: A Theoretical Study. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 51(3), 1643-1654 [10.1109/TGRS.2012.2206817].