African Hydrobasins

HydroBASINS represents a series of vectorized polygon layers that depict sub-basin boundaries 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 catchment topology such as up- and downstream connectivity. HydroBASINS has been extracted from the gridded HydroSHEDS core layers at 15 arc-second resolution. Depiction of nested sub-basin delineations An important characteristic of any sub-basin delineation is the sub-basin breakdown, i.e. the decision of when and how to subdivide a larger basin into multiple tributary basins. At its highest level of sub-basin breakdown, HydroBASINS divides a basin into two sub-basins at every location where two river branches meet which each have an individual upstream area of at least 100 km². A second critical feature of sub-basin delineations is the way the sub-basins are grouped or coded to allow for the creation of nested sub-basins at different scales, or to navigate within the sub-basin network from up- to downstream. To support these functionalities and topological concepts, the ‘Pfafstetter’ coding system has been implemented in the HydroBASINS product offering 12 hierarchically nested sub-basin breakdowns globally.