Simultaneous multi-channel GPR measurements for soil characterization

For agricultural studies, the determination of soil properties such as electromagnetic wave velocity and electrical conductivity is essential for characterizing important hydrological parameters such as soil water content. GPR has shown a high potential to estimate these parameters by using either large-scale common offset measurements and, point-scale common mid-point (CMP) or wide-angle reflection and refraction (WARR) measurements. A new multi-channel ground penetrating radar system combines both techniques and allows fast simultaneous measurements with up to eight channels. Thereby, up to seven receivers are continuous performing common offset measurements that can be rearranged to WARRs. This allows fast tracking of velocity changes along a measurement profile. Here, we present multi-channel and single-channel 500 MHz GPR data measured on a profile with different soil characteristics to demonstrate the potential of this new approach. To eliminate time shifts that are caused by the different cables and receivers of the multi-channel system a time offset correction is suggested. For single- and multi-channel WARR measurements velocity variations of the ground wave along the profile are determined using the semblance analysis. The comparison of the single- and multi-channel data indicate that multi-channel GPR is able to provide velocities similar to single-channel measurements, and, that the method can be used to determine changes of the groundwave velocity with a high spatial coverage.