The rivers of South 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 about 100 km² upstream area.
The stream network dataset consists of the following information: 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).
The attributes table now includes a field named "Regime" with tentative classification of perennial ("P") and intermittent