## 1 Introduction
Soil erosion caused by land degradation affects both natural and human resources, resulting from insufficient agricultural productivity, and is characterized as one of the most important threats worldwide [18]. Forest fires constitute one of the most critical causes of soil erosion due to their ability to burn large amounts of vegetation cover leading to an increase in runoff and sediment transfer [19; 20]. For this purpose, several indices have been developed so as to assess the damage caused by wildfires on soil properties, such as the dNBR (differential NBR), which [8] is calculated based on pre- and post-fire satellite images [21]. Research on soil erosion has been extensively carried out over the past few decades since it is inextricably linked to the world's most serious environmental problems [8]. There are a wide variety of models that have been developed throughout the years considering soil loss assessment in several regions around the world [22]. The most commonly known models are the Universal Soil Loss Equation [23], its revised version (RUSLE) [24], and the Water Erosion Prediction Project (WEPP) [25]. Those models are used for the estimation of long-term average soil erosion values based on information extracted from rainfall data, soil properties, topography, and land cover management. A recent study [2] assessed post-fire effects by mapping burned areas and their burn severity and also the soil erosion for an area within the Lokroi Municipality in Central Greece. This study made use of NBR to map the burned areas and to assess the burn severity with the use of Sentinel-2 and Landsat-8 imagery. In addition, to this affected area, the RUSLE was applied to estimate soil erosion. The combined use of these Earth observation and GIS-based methodologies was important before and after the wildfire and led to the identification of the vulnerable areas within the affected region. Another study was conducted [26] regarding the 2021 wildfires in Greece in Attica, Evia, and Peloponnese. In that study, the erosion vulnerability to these areas was evaluated after the fire events with the use of a GIS Boolean logic-based model. The results of the study led to the erosion risk assessment of these areas, making evident the increased susceptibility to surface runoff erosion. A similar study [27] studied southern Italy's Basilicata region, following an integrated approach with GIS and remote sensing regarding post-fire erosion risk. The soil fire severity was estimated by the use of Sentinel-2 images while the RUSLE was applied for the modeling of pre-fire and post-fire erosion for the first year after the events. Results of the study revealed the complex relations between fire severity and soil erosion factors while helping with soil loss estimation after the fire events. Based on all the above-mentioned, this study aims at the assessment of the impact that the 2021 fire season wildfires had in the region of Attica, Greece. More analytically, four major wildfires of Schinos, Varympompi, Lavreotiki, and Vilia were mapped in an operational way with the use of Sentinel-2 imagery with the normalized burn ratio spectral index-based approach, thus extracting the burned area extent and assessing the burn severity while Corine Land Cover data was also used to analyze the consequences each fire caused. Furthermore, the soil erosion in the affected areas via the implementation of the revised universal soil loss equation (RUSLE) was assessed to estimate the soil loss and potential high-risk areas. In this way, to meet the purpose of this study effectively to gain geospatial intelligence on the effects of these wildfires, the results of all the applied methodologies were used to develop a web app that constitutes an invaluable tool in post-disaster hazard assessment. The results of the study showed the spatial damage that the wildfires caused in Attica in 2021 and they also demonstrated a significant increase in soil erosion in the affected areas.