Characterization of peatlands using integrated ground-penetrating radar and nuclear magnetic resonance geophysical methods

Abstract

Peatlands are crucial in the global carbon and nutrient cycles for water regulation and biodiversity, highlighting their importance, especially during times of global change. Grasping the spatial extent, depth, and internal structure of peatlands is essential for effective restoration and sustainable land use. Geophysical methods provide valuable information on these characteristics at various scales, with varying spatial resolutions and accuracies. This study integrates multiple ground-penetrating radar (GPR) techniques and surface nuclear magnetic resonance (SNMR) to characterize a drained peatland in the Gnarrenburg area of Germany. Constant-offset GPR mapping was used to image peat geometry and internal stratigraphy, while common-midpoint and guided-wave soundings provided velocity–depth models for estimating volumetric water content. SNMR sounding data were inverted to obtain relaxation-time distributions and water-content profiles, and GPR-derived reflectors were incorporated as structural constraints to improve inversion sharpness of internal layering of the peat. Soil cores and ring samples served as ground truth. Our results demonstrate that guided-wave GPR yields precise interval-velocity and water-content profiles, resolving small-scale variations and transitions at the peat–mineral interface. Constrained SNMR inversions successfully identify distinct relaxation-time signatures associated with varying peat decomposition states, particularly distinguishing less and highly decomposed layers. Thus, the combination of GPR and SNMR provides a comprehensive, minimally invasive framework for assessing peatland stratigraphy, water content distribution, and peat degradation. Given their relevance in global change, these encouraging outcomes present an opportunity to observe changes over time, making them especially suitable for costeffective monitoring purposes due to their minimally invasive characteristics. Ultimately, these methods serve as valuable tools for planning and guiding peatland restoration activities.