NASA Goddard's Office of Applied Science is working to operationalize near real-time global flood mapping using available satellite data resources -- currently the twice daily overpass of the MODIS instrument, on the Terra and Aqua satellites. We are working to include additional data sources, such as radar, to improve coverage and accuracy.
This work builds on the long-time expertise and efforts of the Dartmouth Flood Observatory (DFO) to map floodwater extent in detail for active floods. The DFO website provides additional detail, additional products, and archives of historical flood maps. This OAS website provides links and information about the automated daily flood and surface water products produced at NASA Goddard.
In general, the DFO website may have more accurate products as experts have been involved in building the flood extent maps using available data, and are thus able to edit out errors. The OAS website will have more timely products, as they are generated automatically within several hours of satellite overpass and posted on this website, but they have not been manually examined or edited for errors.
Although fairly robust, the current system is still in active development. If you would like to be kept informed of updates and developments, please sign up for the floodmap mailing list. We welcome and encourage any feedback on the products so we can improve their accuracy and useability.