This documentation accompanies a series of polygon layers that depict watershed boundaries and
sub-basin delineations at a global scale. The goal of this product is to provide a seamless global
coverage of consistently sized and hierarchically nested sub-basins at different scales (from tens
to millions of square kilometers), supported by a coding scheme that allows for analysis of
watershed topology such as up- and downstream connectivity.
Watershed boundaries provide important geospatial units for many applications, but at a global
scale there is a lack of high-quality mapping sources. The HydroSHEDS database (Hydrological
data and maps based on SHuttle Elevation Derivatives; Lehner et al. 2008; for more information
see http://www.hydrosheds.org) provides hydrographic data layers that allow for the derivation
of watershed boundaries for any given location based on the near-global, high-resolution SRTM
digital elevation model. Using this hydrographic information, watersheds were delineated in a
consistent manner at different scales, and a hierarchical sub-basin breakdown was created
following the topological concept of the Pfafstetter coding system (Verdin & Verdin 1999). The
resulting polygon layers are termed HydroBASINS and represent a subset of the HydroSHEDS
database.
The HydroBASINS product has been developed on behalf of World Wildlife Fund US (WWF),
with support and in collaboration with the EU BioFresh project, Berlin, Germany; the
International Union for Conservation of Nature (IUCN), Cambridge, UK; and McGill University,
Montreal, Canada. Major funding for this project was provided to WWF by Sealed Air
Corporation; additional funding was provided by BioFresh and McGill University.