Remotely sensed information from satellites and airborne instruments can be used for estimating the extent and dynamics of flood inundation for large areas and can complement in-situ observations. IWMI’s flood risk spatial datasets contain estimated maximum flood inundation extent for South Asia, Southeast Asia and Nigeria.

South Asia
http://waterdata.iwmi.org/Applications/Catastrophic_Flood_Risk_Mapping/
Southeast Asia
http://waterdata.iwmi.org/Applications/Southeast_Asia_Flood_Mapping/
Nigeria
http://waterdata.iwmi.org/Applications/nigeria_Flood_Mapping/