Validation of flood risk maps using open source optical and radar satellite imagery

Abstract

Flood risk maps delineate areas potentially at risk of flooding and are thus a crucial tool in flood risk management. In Spain, such maps are provided as open geospatial data. This article compares the flood-prone areas according to those maps for floods of different return periods with the spatial extent of two floods that severely affected southwestern Spain using open source optical and radar satellite imagery. Results using the recall metric were found to be very good and are the most relevant to emergency preparedness services as this metric focuses on the correctly predicted flooded areas. It was also found that the 500-year flood risk map was the one with the best precision and accuracy for both flood events. The results confirm the accuracy of the flood risk maps based on open source remote sensing imagery and hence demonstrate the potential of publicly available and freely distributed remote sensing data in their development.