UAVs Reveal the Effects of Seismic Lines on Surface Morphology, Water Table Position, and Methane Emissions in Boreal Peatlands

Authors: Greg McDermid*, , Julie Lovitt, University of Calgary, Mir Mustafizur Rahman, University of Calgary, Saraswati Saraswati, University of Waterloo, Maria Strack, University of Waterloo, Bin Xu, NAIT Boreal Research Institute
Topics: Remote Sensing, Water Resources and Hydrology, Environmental Science
Keywords: Remote sensing, wetlands, peatlands, methane
Session Type: Paper
Day: 4/5/2019
Start / End Time: 5:00 PM / 6:40 PM
Room: Marshall North, Marriott, Mezzanine Level
Presentation File: No File Uploaded

Alberta’s peatlands are globally significant stores of soil carbon, where local methane (CH4) emissions are linked to microtopography and water table position: two factors that are notoriously difficult to measure in the field. In this presentation, we show how ultra-high resolution surveys from unmanned aerial vehicles (UAVs or drones) can be used to map microtopography and depth to water over large areas. UAV photogrammetric data were found to capture elevation with accuracies (RMSE) ranging from 14-42cm, depending on the state of vegetation/surface complexity. Regarding water-table mapping, an independent accuracy assessment using 31 temporally coincident water-well measurements revealed accuracies (root mean square error) in the 20-cm range, though errors were concentrated in small upland pockets in the study area, and areas of dense tree covers. In the peatland literature, these capabilities are unique and allow us to reveal — for the first time — the effects of seismic lines (linear petroleum-exploration disturbances) on surface morphology, water table position, and CH4 emissions. Working in a 61-ha treed-bog ecosystem near Peace River, we document how soil compaction on low-impact seismic lines flattens microtopography and decreases the depth to water compared to adjacent natural areas. We found the observed range in microtopographic elevation to be 46 cm lower on seismic lines than surrounding areas, and the mean depth to water to be reduced by an average of 15.4 cm. These alterations are projected to increase CH4 emissions at this site by up to 120%, relative to undisturbed conditions.

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