HydroSHEDS is based on high-resolution elevation data obtained during a Space Shuttle flight for NASA's Shuttle Radar Topography Mission (SRTM). HydroSHEDS stands for "Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales." At the most basic level, HydroSHEDS will allow scientists to create digital river and watershed maps. These maps can then be coupled with a variety of other geo-spatial datasets or applied in computer simulations, such as hydrologic models, in order to estimate flow regimes. See http://www.worldwildlife.org/freshwater/hydrosheds.cfm