From the United Nations Inst. For Training and Research (UNITAR):
…UNOSAT announces the official launch of its flood portal, a dedicated, free-to-use repository where anyone can easily find and download satellite-derived flood data in GIS vector format.
Data was extracted from satellite imagery by UNITAR-UNOSAT during more than 50 flood events occurring since 2006, with new data still being added as new floods occur.
Satellite imagery used for these analyses comes from many different sources, including RadarSat-1, RadarSat-2, Sentinel-1, SPOT-5, TerraSAR-X, Landsat, ALOS PALSAR, ALOS-2 PALSAR-2, and others. In most cases these satellites were activated by UNITAR-UNOSAT under the auspices of the International Charter on Space and Major Disasters.
Data is downloadable in various formats, thereby ensuring successful integration with most platforms. In addition, data can also be accessed via the Humanitarian Data Exchange and ArcGIS Online, facilitating use by the international disaster response and geospatial communities.
Direct to New UNOSAT Flood Portal