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Major River Basins of the World, 2nd ed. (GRDC, 2020)

Recommended citation: GRDC (2020): Major River Basins of the World / Global Runoff Data Centre, GRDC. 2nd, rev. ext. ed. Koblenz, Germany: Federal Institute of Hydrology (BfG).

Introduction

GRDC Major River Basins of the World (MRB) is an ongoing GIS project of the Global Runoff Data Centre (GRDC). It is provided for public use under the condition of full citation and reference to incorporated data from the HydroSHEDS database. This is the 2nd, revised and extended edition 2020 and replaces the basin polygons and river lines of the edition 2007.

 GRDC Major River Basins of the World, 2nd, rev. ext. edition (GRDC, 2020) GRDC Major River Basins of the World 2020 GRDC Major River Basins of the World, 2nd, rev. ext. edition (GRDC, 2020)

Freshwater input into the world's oceans is an important parameter in the global water balance. Rivers return water from land back to the ocean. Rivers carry materials, nutrients and pollutants from rural and urban areas and bring human impacts from land into the oceans. Large rivers in particular drain transboundary basins with competing interests and demands on the management of the shared resources. Against this background, drainage basins may be considered “major” in terms of basin size, water quantity and quality, but also in their hydro-political relevance or interest.

In 2007, GRDC generated the first version of the Major Rivers Basins of the World dataset. Based on the flow direction dataset of HYDRO1k (USGS 2000), 405 basin polygons were derived. The river network of 687 associated river lines was generated in close collaboration with the German Federal Institute for Geosciences and Natural Resources (BGR) on the basis of their Major River Basins (BGR 2004) dataset.

With the HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales) mapping product a “suite of geo-referenced data sets in raster and vector format, including stream networks, watershed boundaries, drainage directions, and ancillary data layers such as flow accumulations, distances, and river topology information” (Lehner 2013) became available in a consistent format. HydroBASINS dataset provides a series of polygon layers of watershed boundaries and nested basin delineations following the Pfaffstetter coding principles. The HydroRIVERS dataset provides a global coverage of river reaches at high spatial resolution, each with a reference to the corresponding hydro-basin identifier. The HydroSHEDS datasets and more information are available at http://www.hydrosheds.org.

Seamless global coverage and 12 levels of sub-basin breakdown of HydroSHEDS offer the unique opportunity to base GRDC’s geospatial data products like the Major River Basins of the World datasets on a comprehensive and widely accepted data product. We used the HydroBASINS (WWF 2013) subset of polygon layers for a review of basin boundaries, and the HydroRIVERS subset (WWF 2019) of polylines to derive river networks associated to the basin polygons. It is important to note, that GRDC has not re-assembled the river or lake basins or delineated new watershed boundaries.

GRDC Major River Basins 2020

The Major River Basins 2020 dataset is extracted from the HydroBASINS dataset using basic selection and generalization procedures. The basin polygons of edition 2007 were reviewed against the hybas-polygons of the HydroSHEDS dataset (online received in March 2018) and extended for 115 so-called WMO-Basins (GRDC 2020) which represent specific river basins.

GRDC Major River Basins of the World: Major river basins 2020 GRDC Major River Basins of the World: Major river basins 2020GRDC Major River Basins of the World: Major river basins 2020

River basin polygons are generated from dissolving hybas-polygons at the highest spatial resolution level (hybas_lev12) that intersect a basin polygon of the extended edition 2007, always inspecting the basin polygons at the next (coarser) generalization levels. In this way, basin polygons are generated to build up the new dataset of 520 major river basins.

River basin polygons are attributed with: basin identifier, basin name and description, continent from which the water comes, sea and ocean into which the water flows, and an approximate of drainage area. Drainage area (in square km) is calculated by adding up the sub-area values specified in the hybas_lev12 datasets and does not reflect the real size of basin area. The calculated drainage area per basin ranges from 682 km² for the smallest basin (Coatan river basin, shared by Mexico and Guatemala) up to 6 Mio km² for the Amazon river basin. Overlaying basin boundaries with national borders, more than 250 of the 520 major river basins appear to be transboundary, more than 90 basins shared by three or more countries.

GRDC Major River Networks 2020

The Major River Networks 2020 dataset is extracted from HydroSHEDS dataset using basic selection and generalization procedures.

GRDC Major River Basins of the World: Major river networks 2020 GRDC Major River Basins of the World: Major river networks 2020GRDC Major River Basins of the World: Major river networks 2020

The Major River Networks 2020 are generated from dissolving river-reaches of the HydroRIVERS dataset (online received in February 2020) that intersect the major river basin polygons. To allow for displaying a scalable network of streams for both the smallest river basin and a huge basin, a subset of hydrorivers_v10 reaches where the “upland area” exceeds the median of all upland area values of 35.59 km² is selected and split by deciles into ten subsets of hydro-river reaches. At the highest level (above the 0.9 quantile) river networks for 475 (of 520) major river basins are displayed. In this way, river networks may be assigned to the 520 major river basins and further densified by activating river network slices.

River networks are attributed with properties of the associated basin: basin identifier, basin name and description, continent from which the water comes, sea and ocean into which the water flows, and an approximate of drainage area.

GRDC Major Rivers 2007

The river lines of edition 2007 display 687 rivers associated with river basin polygons of edition 2007. Among other attributes, a long-term average discharge value along the river course is provided, calculated from generated mean discharge 1961-1990 as computed with WaterGAP 2.1 (University of Frankfurt, 2007) at a spatial resolution of 0.5 degree. The modelled river discharge values were grouped into ten classes and each river segment was assigned to a river class (category). Each class (category) represents an interval of discharge values in km³/year. The maximum (highest) assigned category along a river was picked to label the average discharge from the associated drainage basin at the river outlet.

GRDC Major River Basins of the World: Major rivers 2007 GRDC Major River Basins of the World: Major rivers 2007GRDC Major River Basins of the World: Major rivers 2007

An update of the calculated discharge using a new version of WaterGAP model is intended but not yet ready to update the river discharge attributes. For the time being, the river lines layer of edition 2007 with calculated discharge values is still provided. Please note, that the river lines 2007 in some cases do not fit with river basin polygons 2020 which are generated using the HydroSHEDS dataset.

References

BGR (2004): Major River Basins. Federal Institute for Geosciences and Natural Resources, BGR. Hanover, Germany.

IHO (1953): Limits of Oceans and Seas. International Hydrographic Organization, Special Publication No 23, 3rd Edition, IMP, Monégasque - Monte-Carlo, 45 pp. Online available at https://epic.awi.de/id/eprint/29772/1/IHO1953a.pdf

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.

Lehner, B. (2013): HydroSHEDS technical documentation, version 1.2. World Wildlife Fund US, 1–25.

USGS (2000): HYDRO1k Elevation Derivative Database. US Geological Survey EROS Data Center, Sioux Falls, SD.

WWF (2013): HydroBasins, World Wildlife Fund. Data online available at www.hydrosheds.org. Online received in March 2018.

WWF (2019): HydroRivers, World Wildlife Fund. Data online available at www.hydrosheds.org. Online received in February 2020.

Acknowledgments

This product “Major River Basins of the World” incorporates data from the HydroSHEDS database which is © World Wildlife Fund, Inc. (2006-2013) and has been used herein under license. WWF has not evaluated the data as altered and incorporated within “Major River Basins of the World”, and therefore gives no warranty regarding its accuracy, completeness, currency or suitability for any particular purpose. Portions of the HydroSHEDS database incorporate data which are the intellectual property rights of © USGS (2006-2008), NASA (2000-2005), ESRI (1992-1998), CIAT (2004-2006), UNEP-WCMC (1993), WWF (2004), Commonwealth of Australia (2007), and Her Royal Majesty and the British Crown and are used under license. The HydroSHEDS database and more information are available at http://www.hydrosheds.org.

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 GRDC Major River Basins of the World, 2nd, rev. ext. edition (GRDC, 2020) GRDC Major River Basins of the World 2020Click to download a tabular summary of major river basins

Data can be downloaded as ESRI Layer Package (LPK) files for use within ESRI ArcMap, or ESRI Shape files. Please note: ESRI Layer Package files cannot be read with QGIS. Please cite the files in all publications and products.

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