Integrating TDR and GPR methods to study the structure of peatland

Abstract

In this study we compared time-domain reflectometry (TDR) data from boreholes and the results of ground-penetrating radar (GPR) along the cross-sections on a peat deposit. The studied mire located on the Zaonezhye Peninsula (Republic of Karelia, Russia); its structure included layers of peat and bedding lake sediments. To perform the measurements we used GPR with antenna unit 150 MHz and TDR system TDR200 with probe. The mire structure was characterized by a medium basin structure (7 m max depth) and sloping mire topographic. Comparison TDR and GPR data yielded similar dielectric constant values for peat layers. The average mistake in dielectric constant values between TDR and GPR observation was 5 units. The conditions for the formation of interfaces on GPR cross-sections were studied by analyzing dielectric constant change across the peat deposit. We found that the depth positions of the GPR interfaces were quite accurately (±20 cm) coincides with the intervals of the change of peat type. Our results indicate the difficulty of interpreting GPR cross-sections contained multi-reflectors for subsurface with sub-horizontal structure such as peat deposits or lakes bottom sediments.