High-resolution Earth Observation data and spatial analysis for burn severity evaluation and post-fire effects assessment in the Island of Chios, Greece

摘要

Forest fires are regarded as one of the most threatening sources of disturbance for the property, infrastructure as well as ecosystems. The present study aimed at analyzing spectral information products derived from the Landsat-8 OLI sensor together with spectral indices to evaluate their ability to map burn scars and burn severity. In particular the study objectives were: (1) to identify the capability of OLI to burnt area mapping and burn severity, (2) to evaluate the contribution of several spectral indices to the overall accuracy (3) to assess post-fire effects such as flood risk and, (4) to investigate the vegetation re-growth in relation to the burn severity. As a case study, Chios Island was selected due to the recent fire event in the south-western part of the island (25/07/2016). Three multispectral Landsat-8 OLI images, acquired on 13/07/2016 (pre-fire), 15/09/2016 (post-fire) and 27/03/2017 (six months after the fire), were utilized. Several spectral indices were implemented to detect the burnt areas and assess the burn severity (Burn Area Index - BAI, Normalized Burn Ratio - NBR, Normalized Burn Ration + Thermal - NBRT), as well as to evaluate the vegetation conditions and re-growth six months after the fire event (Normalized Difference Vegetation Index - NDVI and the Normalized Difference Water Index - NDWI). Additionally, NBR index of pre- and post-fire images was calculated in a difference change detection procedure which estimates the Differenced Normalized Burn Ratio dNBR. Overall, a total burned area of 45,9 km2 was delineated, and both burned severity map and vegetation recovery map were created and evaluated.