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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.
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Lehner, B., Grill G. (2013). Global river hydrography and network routing: baseline data and new approaches to study the world’s large river systems. Hydrological Processes, 27(15): 2171–2186.

The polygon data sets of HydroBASINS are distributed in ESRI ‘shapefile’ format (ESRI 1998). Each HydroBASINS shapefile consists of five main files (.dbf, .sbn, .sbx, .shp, .shx). Additionally, basic metadata information is provided in XML format (.xml). Projection information is provided in an ASCII text file (.prj). All shapefiles are in geographic (latitude/longitude) projection, referenced to datum WGS84.

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