Mapping and monitoring peatlands in the Belgian Hautes Fagnes: Insights from Ground-penetrating radar and Electromagnetic induction characterization

Henrion, Maud [UCL] Li, Yanfei [UCL] Koganti, Triven [UCL] Bechtold, Michel Jonard, François [UCL] Opfergelt, Sophie [UCL] Vanacker, Veerle [UCL] Van Oost, Kristof [UCL] Lambot, Sébastien [UCL]

Peatlands are vital ecosystems providing crucial ecological services such as significant carbon storage in the context of climate change. These sensitive ecosystems are subjected to degradation due to land use change. In this context, it is important to understand the actual state of degraded peatlands and their recovery potential for regaining important functions. This study focuses on a disturbed peatland in the Belgian Hautes Fagnes, previously drained and planted with spruce, and characterized by a topographic gradient. We aimed to elucidate the use of Ground-penetrating radar (GPR) and Electromagnetic induction (EMI) techniques in characterizing such peatlands, with a specific focus on their implications for peat depth and electrical conductivity assessment, related to peatland degradation. The GPR revealed a high spatial heterogeneity in peat depth, ranging from 0.2 to more than 2 m on the site. In contrast, an EMI instrument used with single coil spacing proved to be unsuccessful to deduce peat depth but demonstrated potential for the delineation of zones of mineral soil. It is also shown that the links between soil physical and chemical properties and its bulk soil electrical conductivity (ECa) measured by EMI are complex in zones of shallower peat. Additionally, this study highlights the role of pore water conductivity in influencing temporal variations in ECa. Our findings explain the intricate interplay between peat depth, topography and ECa in disturbed peatlands. The results of this study may be of substantial societal interest, as it provides insights into techniques for the rapid non destructive characterization of the conditions of previously drained peatlands.