The rivers of North America are derived from the World Wildlife Fund's (WWF) HydroSHEDS drainage direction layer and a stream
network layer. The drainage direction layer was created from NASA's Shuttle Radar Topographic Mission (SRTM) 15-second Digital
Elevation Model (DEM). The raster stream network was determined by using the HydroSHEDS flow accumulation grid, with a threshold
of 1500 upstream cells.
The stream network dataset consists of the following information:- unique arc identifier (ARCID), the origin node of each
arc in the network (FROM_NODE), the destination of each arc in the network (TO_NODE), the Strahler stream order of each
arc in the network (STRAHLER), numerical code and name of the major basin that the arc falls within (MAJ_BAS and MAJ_NAME);
- area of the major basin in square km that the arc falls within (MAJ_AREA); - numerical code and name of the sub-basin
that the arc falls within (SUB_BAS and SUB_NAME); - area of the sub-basin in square km that the arc falls within (SUB_AREA);
- numerical code of the sub-basin towards which the sub-basin flows that the arc falls within (TO_SUBBAS) (the codes -888
and -999 have been assigned respectively to internal sub-basins and to sub-basins draining into the sea).