Peatland Volume Mapping Over Resistive Substrates With Airborne Electromagnetic Technology

Abstract

Despite the importance of peatlands as carbon reservoirs, a reliable methodology for the detection of peat volumes at regional scale is still missing. In this study we explore for the first time the use of airborne electromagnetic (AEM) to detect and quantify peat thickness and extension of two bogs located in Norway, where peat lays over resistive bedrock. Our results show that when calibrated using a small amount of field measurements, AEM can successfully detect peat volume even in less ideal conditions, that is, relatively resistive peat over resistive substrata. We expect the performance of AEM to increase significantly in presence of a conductive substratum without need of calibration with field data. The organic carbon content retrieved from field surveys and laboratory analyses combined with the 3‐D model of the peat extracted from AEM allowed us to quantify the total organic carbon of the selected bogs, hence assessing the carbon pool.

Quantification of Peat Thickness and Stored Carbon at the Landscape Scale in Tropical Peatlands: A Comparison of Airborne Geophysics and an Empirical Topographic Method

“…Correlations between peat thickness and soil surface elevation extracted from studies that report measurements recorded in locations situated in Asia, Africa, Europe, South, and North America. Data are extracted from the following sources: (a) – Cameron and Schruben () (dark red crosses: first bog to the left of “their figure ”, points 49‐5; blue triangles: third bog from the left of “their figure ” points 68‐16 – Maine, USA); (b) – Cubizolle et al () (France); (c) – Kowalczyk et al () (purple circles – Poland) and Silvestri et al () (orange squares – Norway); (d) – Esterle and Ferm () (“their figure ” – yellow circles – Indonesia); (e) – Esterle and Ferm () (“their figure ” – blue diamonds – Indonesia), Supardi and Neuzil () (“their figure ” – red squares – Indonesia), Page et al () (green crosses – Indonesia), Anshari, personal communication (purple triangles – Indonesia); (f) – Dargie et al () (Congo); (g) – Lähteenoja and Page () – (“their Figure a” – dark red squares – Peru and “their Figure b” – gray circles – Peru); (h) – Lähteenoja and Page () (“their Figure d” – Peru). The elevation is referred to a different zero for each data set, e.g., referred to the mean sea level or to another local reference as specified in the supporting information.…”

Mapping of Peat Thickness Using a Multi-Receiver Electromagnetic Induction Instrument

“…Remote sensing and airborne geophysical techniques represent the most suitable means to investigate peatlands at a large scale (>10 km 2 ). Several recent studies have successfully used airborne electromagnetic (AEM) methods to estimate peatland thickness and extent [14][15][16][17]. Likewise, different proximal or ground-based geophysical sensors have been accurately applied to map peat properties at smaller scales.…”

Airborne Electromagnetic and Radiometric Peat Thickness Mapping of a Bog in Northwest Germany (Ahlen-Falkenberger Moor)

“…The next step was to analyze the airborne electromagnetic (HEM) data in order to derive estimates for the location of the peat base. This interface should be detectable, if the resistivity of peat differs significantly from the resistivity of the substrate [11][12][13][14]. The resulting peat thickness could then be used to scale the HRD data (exposure rate).…”

“…Puranen et al [11] and Airo et al [7] published results from Finland, and Beamish and Farr [12] from Wales, using fixed-wing frequency-domain systems. More recently, Silvestri et al [13,14] presented peat thickness results acquired by helicopter-borne time-domain electromagnetic devices in Norway and Indonesia.…”