Flood impact assessment on agricultural and municipal areas using Sentinel-1 and 2 satellite images (case study: Kermanshah province)

Flooding stands as one of the most devastating natural occurrences, warranting immediate investigation to mitigate its destructive impact. The inundation of agricultural lands and settlements has led to adverse consequences. Remote sensing emerges as a widely applicable and expeditious method for addressing these challenges. Within the scope of this study, S1A SAR data with VH descending pass and S2 data from 01/03/2019 to 20/03/2019 and 25/03/2019 to 20/04/2019 were leveraged to assess the pre- and post-flood periods in Kermanshah province. MNDWI and NDWI techniques were employed to identify water zones in the S2 imagery, subsequently was used for validating of S1 images. The calculated RMSE and correlation coefficients yielded values of 0.27 and 0.93, respectively. It was observed that radar imagery exhibits superior quality to optical imagery in flood scenarios characterized by cloudy and rainy weather. MODIS, Hydrosheds, and SRTM satellite images were utilized as distinct filters to identify land use, permanent water bodies, and areas with a slope exceeding 5%. The findings indicated that a total of 36,849 ha of land were affected by the flood, encompassing 7073 and 4224 ha of agricultural and urban areas, respectively, which were susceptible to destruction during this period. The NDWI and MNDWI indices estimated the flooded area to be 30,179 and 32,540 ha, respectively, representing lower values compared to the results obtained from the S1 data.