Analysis of the burned area in Grebaštica using Sentinel-2 satellite imagery and vegetation indices

Abstract: This study analyzed the area of Grebaštica, located in the Šibenik-Knin County, before and after a major fire that occurred on 13 July 2023, with the aim of calculating the extent of the burned area using Sentinel-2 satellite imagery and QGIS software. Three vegetation indices were used for the analysis: the Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI), and the Normalized Burn Ratio (NBR). Low values of these indices indicate significant damage to vegetation and soil. The analysis revealed that the NBR index was the most effective for detecting burned areas due to the high reflectance of vegetation in the near-infrared and shortwave infrared regions of the electromagnetic spectrum, while the NDVI index proved to be the least effective. To calculate the area affected by the fire, the delta Normalized Burn Ratio (dNBR or ΔNBR) was also computed. Using the ΔNBR index, different levels of vegetation damage and fire hazard were identified. These indices enabled clear differentiation between damaged and undamaged areas, based on the specific reflectance characteristics of materials affected by fire. Key words: burned area, Grebaštica, vegetation indices, NBR, satellite imagery