Imaging tropical peatlands in Indonesia using ground-penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization

Abstract

Abstract. Current estimates of carbon (C) storage in peatland systems worldwide indicate that tropical peatlands comprise about 15 % of the global peat carbon pool. Such estimates are uncertain due to data gaps regarding organic peat soil thickness, volume and C content. We combined a set of indirect geophysical methods (ground-penetrating radar, GPR, and electrical resistivity imaging, ERI) with direct observations using core sampling and C analysis to determine how geophysical imaging may enhance traditional coring methods for estimating peat thickness and C storage in a tropical peatland system in West Kalimantan, Indonesia. Both GPR and ERI methods demonstrated their capability to estimate peat thickness in tropical peat soils at a spatial resolution not feasible with traditional coring methods. GPR is able to capture peat thickness variability at centimeter-scale vertical resolution, although peat thickness determination was difficult for peat columns exceeding 5 m in the areas studied, due to signal attenuation associated with thick clay-rich transitional horizons at the peat-mineral soil interface. ERI methods were more successful for imaging deeper peatlands with thick organomineral layers between peat and underlying mineral soil. Results obtained using GPR methods indicate less than 3 % variation in peat thickness (when compared to coring methods) over low peat-mineral soil interface gradients (i.e., below 0.02 • ) and show substantial impacts in C storage estimates (i.e., up to 37 MgC ha −1 even for transects showing a difference between GPR and coring estimates of 0.07 m in average peat thickness). The geophysical data also provide information on peat matrix attributes such as thickness of organomineral horizons between peat and underlying substrate, the presence of buried wood, buttressed trees or tip-up pools and soil type. The use of GPR and ERI methods to image peat profiles at high resolution can be used to further constrain quantification of peat C pools and inform responsible peatland management in Indonesia and elsewhere in the tropics.

Application of electrical resistivity imaging (ERI) for the assessment of peat properties: a case study of the Całowanie Fen, Central Poland

“…These laboratory tests have not been explicitly confirmed by the field surveys presented in this paper. This results probably from the spatial variability of the peatland and influence of individual factors (such as moisture content, ash The ERI method may be useful for determining the stratigraphic contact between the peat layer and the mineral substrate (Slater and Reeve 2002;Comas et al 2015;Walter et al 2016), which is also confirmed by this report.…”

“…Detailed information from the GPR survey (Kowalczyk et al 2014) would be very difficult to obtain using data solely from the drillings. The potential of GPR and ERI for estimating peat thickness was confirmed by Comas et al (2015). However, these researchers indicate the limitations of geophysical methods in determining the thickness of the peat.…”

“…Peatlands are investigated mostly using the ground penetrating radar (GPR) method. Only a few researchers (e.g., Slater and Reeve 2002;Comas et al 2015;Walter et al 2016) have applied induced polarization imaging, electromagnetic terrain conductivity and electrical resistivity imaging, apart from the GPR method, as alternative tools to determine the peatland thickness.…”

Identifying Peat Soil Layers in the South Kalimantan, Indonesia Using K-Means Clustering

“…The study of peat soil has developed rapidly to be able to determine carbon emissions, especially in the peatlands of Indonesia [1][2][3][4][5][6][7]. A large amount of carbon emission is produced by peatlands, which is mostly determined by the depth or the thickness of the peat [1,2,8].…”

“…A large amount of carbon emission is produced by peatlands, which is mostly determined by the depth or the thickness of the peat [1,2,8]. Accurate information parameters on the depth and the thickness of the peat must be used in this research.…”