Flooding Zone Extracting Using Spectrum Proportionality of Sentinel-2 and Landsat-8 Satellite Data (Case Study: Aq’Qala County Flooding)

Nowadays, the environmental structure has been changing and natural disasters, including sudden floods increasing. Due to the crossing of Gorganrood River in the city of Aq’qala, it has always been in the risk of flood in the spring and summer. In this study for time series flood zones and flood’s map area calculating which occurred in 23rd March 2019, we used Sentinel-2 and Landsat-8 data because of high spatial resolution and free accessibility. For removing noise and clouds applied the atmospheric and radiometric correction on images and then used MNDWI and NDWI indexes for identifying of water and high moisture soil. The results shown the MNDWI index was better than the NDWI index for identify the moody water and high moisture zones. Flood zones maps produced by MNDWI index are shown more flooding area than NDWI index map. The area of flood maps for Aq’qala county and Aq’qala city were 262.453 and 51.091 Km2, respectively. The maximum flow rate discharge with 50 years returns period was 739 m3/s that the northern and eastern of Aq’qala city were flooded. When the flood is muddy, using MNDWI index is 50 percent better than NDWI index.