Microtopographic and Hydrological Response to Repeated Seismic Line Disturbance in a Boreal Fen of Northern Alberta, Canada

Seismic lines are among the most widespread anthropogenic disturbances in Alberta’s boreal peatlands, where repeated petroleum-exploration surveys can alter surface morphology, hydrology, and recovery potential. Although low-impact seismic (LIS) techniques are designed to minimize ground disturbance, the long-term consequences of re-using existing lines remain poorly understood. This study used remotely piloted aircraft system (RPAS)-based LiDAR and optical imagery to examine how peatland microtopography and hydrology evolve following repeated seismic surveys. We quantified four attributes—ground depression, hummock cover, depth to water, and surface water cover—across new seismic lines (cut in 2021), old seismic lines (cut in 1996), and re-disturbance (cut in 1996, re-cut in 2021) LIS lines, as well as adjacent undisturbed peatland, in a boreal fen of northern Alberta. New disturbances were depressed by approximately 10 cm relative to the surrounding peatland and exhibited reduced microtopographic variability. Hummock cover decreased from 21% in the matrix to 6% on new disturbances. Old disturbances showed greater heterogeneity than new disturbances, with hummock cover partially recovering to 14% and surface water increasing from 7% to 27%, reflecting greater spatial heterogeneity in surface conditions. Re-disturbances exhibited microtopographic conditions similar to or more degraded than old disturbances, with hummock cover reduced to 2% and persistently high surface water cover (27%). These patterns suggest that repeated seismic surveys may limit recovery and maintain altered hydrological and microtopographic conditions. Within the context of this case study, even narrow LIS corridors were associated with persistent alterations when re-used, highlighting the importance of considering re-use effects when developing management strategies for peatland ecosystems. RPAS data provide an effective means to quantify these fine-scale changes and inform peatland restoration and seismic line management.