This river network (stream lines) map for South America is derived from the flow direction map for South America. The flow accumulation map for South America is used for selection and attribution. Only rivers with upstream drainage areas exceeding a certain threshold are selected: for the 15 arc-second resolution a threshold of 100 upstream cells has been used. The vectorized river reaches are attributed with the maximum flow accumulation (in number of cells) occurring within each river reach. This data is derived from elevation data of the Shuttle Radar Topography Mission (SRTM) at 30 arc-second resolution approx. 1km at the equator.The goal of developing HydroSHEDS was to generate key data layers to support regional and global watershed analyses, hydrological modeling, and freshwater conservation planning at a quality, resolution and extent that had previously been unachievable.