Comparison of SAR amplitude vs. coherence flood detection methods - a GIS application

Flood area detection from multipass Synthetic Aperture Radar (SAR) data can be performed via amplitude change detection techniques. These methods allo w flooded zones to be discriminated only when they are flooded at the time of the second passage, and not at the time of the first one. Coherence deri ved from multipass SAR interferometry can be used instead, as an indicator of changes in the electromagnetic scattering behaviour of the surface, thus potentially revealing all the areas affected by the flood event at any tim e between the two passes. The paper presents a prototype application of suc h techniques, that is, a flood map obtained from ERS-1/2 data taken over Be ziers (Southern France), through proper thresholding of a combination of am plitude and coherence information. Produced in the framework of an ESA proj ect, the map consists of a DXF vector file which can be imported directly i nto most commercial GIS software.