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.

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.

At its highest level of sub-basin breakdown, HydroBASINS encompasses 1.0 million individual sub-basin polygons with an average area of 130.6 km², representing a total of 135.0 million km² of global land area (excluding Antarctica). HydroBASINS only includes a limited amount of (mostly geometric) attribute information, such as the sub-basin area, the distance from upstream headwaters and ocean outlet, and the Pfafstetter coding.

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Note that the overarching HydroATLAS database fully contains all sub-basin polygons of HydroBASINS, which have additionally been enhanced in HydroATLAS with a large number of hydro-environmental characteristics.

For more information on HydroBASINS please refer to the HydroBASINS Technical Documentation.

The HydroBASINS database is freely available for scientific, educational and commercial use. The data are distributed under the same license agreement as the HydroSHEDS core products, which is included in the HydroSHEDS Technical Documentation. For all regulations regarding license grants, copyright, redistribution restrictions, required attributions, disclaimer of warranty, indemnification, liability, and waiver of damages, please refer to the license agreement.

By downloading and using the data the user agrees to the terms and conditions of this license.

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. https://doi.org/10.1002/hyp.9740