University of Oulu

Ikkala L, Ronkanen A-K, Ilmonen J, Similä M, Rehell S, Kumpula T, Päkkilä L, Klöve B, Marttila H. Unmanned Aircraft System (UAS) Structure-From-Motion (SfM) for Monitoring the Changed Flow Paths and Wetness in Minerotrophic Peatland Restoration. Remote Sensing. 2022; 14(13):3169.

Unmanned aircraft system (UAS) structure-from-motion (SfM) for monitoring the changed flow paths and wetness in minerotrophic peatland restoration

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Author: Ikkala, Lauri1; Ronkanen, Anna-Kaisa2; Ilmonen, Jari3;
Organizations: 1Water, Energy and Environmental Engineering Research Unit, Faculty of Technology, University of Oulu, P.O. Box 4300, FIN-90014 Oulu, Finland
2Finnish Environment Institute (SYKE), University of Oulu, P.O. Box 413, FI-90014 Oulu, Finland
3Metsähallitus Parks and Wildlife Finland, P.O. Box 94, FI-01301 Vantaa, Finland
4Department of Geographical and Historical Studies, Faculty of Social Sciences and Business Studies, Joensuu Campus, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.1 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2022
Publish Date: 2022-12-05


Peatland restoration aims to achieve pristine water pathway conditions to recover dispersed wetness, water quality, biodiversity and carbon sequestration. Restoration monitoring needs new methods for understanding the spatial effects of restoration in peatlands. We introduce an approach using high-resolution data produced with an unmanned aircraft system (UAS) and supported by the available light detection and ranging (LiDAR) data to reveal the hydrological impacts of elevation changes in peatlands due to restoration. The impacts were assessed by analyzing flow accumulation and the SAGA Wetness Index (SWI). UAS campaigns were implemented at two boreal minerotrophic peatland sites in degraded and restored states. Simultaneously, the control campaigns mapped pristine sites to reveal the method sensitivity of external factors. The results revealed that the data accuracy is sufficient for describing the primary elevation changes caused by excavation. The cell-wise root mean square error in elevation was on average 48 mm when two pristine UAS campaigns were compared with each other, and 98 mm when each UAS campaign was compared with the LiDAR data. Furthermore, spatial patterns of more subtle peat swelling and subsidence were found. The restorations were assessed as successful, as dispersing the flows increased the mean wetness by 2.9–6.9%, while the absolute changes at the pristine sites were 0.4–2.4%. The wetness also became more evenly distributed as the standard deviation decreased by 13–15% (a 3.1–3.6% change for pristine). The total length of the main flow routes increased by 25–37% (a 3.1–8.1% change for pristine), representing the increased dispersion and convolution of flow. The validity of the method was supported by the field-determined soil water content (SWC), which showed a statistically significant correlation (R² = 0.26–0.42) for the restoration sites but not for the control sites, possibly due to their upslope catchment areas being too small. Despite the uncertainties related to the heterogenic soil properties and complex groundwater interactions, we conclude the method to have potential for estimating changed flow paths and wetness following peatland restoration.

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Series: Remote sensing
ISSN: 2072-4292
ISSN-E: 2072-4292
ISSN-L: 2072-4292
Volume: 14
Issue: 13
Article number: 3169
DOI: 10.3390/rs14133169
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
213 Electronic, automation and communications engineering, electronics
218 Environmental engineering
Funding: This work was supported by the Hydrology LIFE project by European Union LIFE Programme: LIFE16 NAT/FI/000 583; WaterJPI WaterWorks2017 ERA-NET Cofund project WaterPeat (project number 326848). The writing was supported by Hydro-RDI-Network (grant numbers 337280 and 337523) by the Academy of Finland no. 337280 and Maa- ja Vesitekniikan tuki ry no. 14-8844-22. T.K. was funded by the Strategic Research Council (SRC) decision no. 312636 (IBC-Carbon) and by Academy of Finland decision no. 347862 (C-NEUT).
Academy of Finland Grant Number: 326848
Detailed Information: 326848 (Academy of Finland Funding decision)
337523 (Academy of Finland Funding decision)
Copyright information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (