Identifying and Characterising UK Upland Wildfires Using Sentinel-1 Radar

UK peatlands represent a significant terrestrial Carbon store of >2000 Mt, while also supporting a biodiverse ecosystem (Billet et al., 2010). Severe wildfires damage peatlands, removing vegetation and burning peat, often leaving the area in a degraded state. Monitoring burn scar location and persistence is important for targeting restoration works, but mostly relies on ground surveying, with mapping using optical satellite imagery limited by cloud cover in the UK (Armitage et al., 2007). Satellite radar for burn scar mapping is well established in Boreal, Mediterranean and tropical regions (Joyce et al., 2009). ERS-2 is effective in detecting larger UK wildfires, though little has been done with more recent radar data (Millin-Chalabi, McMorrow and Agnew, 2014). Similarly, further understanding of surface factors affecting radar backscatter is required. Therefore, three Peak District burn scars from 2018, two at Dovestone Reservoir and one at Big Moor, are used to investigate the potential of using Sentinel-1 radar imagery for UK burn scar detection and characterisation. For pre- and post-fire images, time-series of SAR intensity and InSAR coherence products will be produced and assessed (Millin-Chalabi, McMorrow and Agnew, 2014). Ground-truth data from burn perimeter and vegetation surveys, supported by Sentinel-2 imagery, will be used to assess the accuracy of burn scar detection using the above products. The spatial and temporal variability of both intensity and coherence products will be assessed in the context of soil moisture, phenological changes and topography. This will inform the interpretation of burn scar characteristics by constraining the surface factors influencing radar backscatter differences. Upon completion, a method replicable for future UK peatland wildfire identification using Sentinel-1 radar, with quantified factors influencing backscatter variability, will be produced.