Using GPR on an ombrotrophic bog in Slovenia to delineate peat morphology

Ground penetrating radar (GPR) was used to study the peat thickness and morphology of the Šijec bog. The Šijec bog on the Pokljuka plateau is one of the southernmost ombrotrophic peatlands in Europe. To test the applicability of the GPR method in peatlands, which was the first study of its kind in Slovenia, we used two different antennas, a 250 MHz shielded and a 50 MHz unshielded Rough Terrain Antenna (RTA). Comparing the results of both applied frequency antennas and systems, we found that the penetration depth of the 250 MHz antenna was not sufficient to detect the peat thickness in the deepest areas. In addition, on the rough terrain, the unshielded flexible 50 MHz RTA antenna (9.25 m long tube) was generally found to be more suitable due to its easier maneuvering. Based on 13 profiles, four depressions were identified within the peat bog and a 3D model was created. The contact between the peat layer and underlying clay sediments derived from the GPR results was complemented with manual peat probing. The results of the study show that GPR is faster and provides larger and continuous information on the thickness, volume, and geometry of peatland compared to conventional surveying methods (peat probe, coring).