Updating the Register of International River Basins of the world

ABSTRACT

The delineation of the world’s international river basins has not been undertaken by any formal body since 1978. Researchers with the Transboundary Freshwater Dispute Database have attempted to fill this void through the 1999 Register, with online updates and currently with the present study. This current register delineates 310 international river basins, reflecting changes in political boundaries and increased data quality. These basins are shared by 150 countries and disputed areas, cover 47.1% of the Earth’s land surface and include 52% of the world’s population. This paper lists all international river systems, their basin areas, their riparian states and their respective territorial percentages.

KEYWORDS:

• international river basin
• Register of International River Basins
• Transboundary Freshwater Dispute Database
• transboundary waters
• shared waters
• international watercourse

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Acknowledgements

This current Register of International River Basins owes so much to so many, including to all who contributed to prior versions. Work on the 1999 version was performed under the auspices of the Committee for International Collaboration of the International Water Resources Association, chaired by Asit K. Biswas, with funding from the US Institute of Peace and the Nippon Foundation, and in close collaboration with the US Geological Survey, among others. A major update was undertaken in the framework of the Transboundary Waters Assessment Programme (TWAP) initiated by the Global Environment Facility (GEF) in which we provided the foundational units of analysis for the broader assessment presented in UNEP-DHI and UNEP (2016) and at http://twap-rivers.org/. That effort was led at our end by Lucia De Stefano, with substantive contribution by Eric Sproles. The authors acknowledge the important role of coordination for the River Component of the TWAP work by the team at the DHI Group – Peter Koefoed Bjørnsen, Paul Glennie and Maija Bertule – as well as the constructive and fruitful collaboration with the project partners: DHI-UNEP Partnership; Columbia University Center for Environmental Systems Research; Center for International Earth Science Information Network, City University of New York; Delta Alliance; International Union for the Conservation of Nature; International Geosphere-Biosphere Program, Stockholm International Water Institute, and the University of Kassel Center for Environmental Systems Research. The authors thank Doug Wood, who worked on data processing in the first part of the project; Susanne Schmeier for contributing data to the analysis and for valuable feedback on an earlier version of this work; and Lynette de Silva for continued assistance and coordination work throughout development of the study. This current version owes a tremendous debt to the talented team of then-students at Oregon State University, all now noted professionals, especially Jim Duncan, Jim Eynard, Kate Jones, Jacob Petersen-Perlman, Dacotah Splichalova and Jen Veilleux, along with intern Chris Paola. Gordon Grant and Bernhard Lehner helped us figure out where a river ends, a surprisingly difficult problem.

Data Availability Statement

The data that support the findings of this study are openly available in the Transboundary Freshwater Dispute Database at http://transboundarywaters.science.oregonstate.edu/content/transboundary-freshwater-dispute-database/.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. The Register of International River Basins was an original component of the Transboundary Freshwater Dispute Database. For the current update and several updates to the listing and delineation of international rivers, see the database at http://transboundarywaters.science.oregonstate.edu/.

2. Separately, Beck et al. (2014) also completed a comprehensive analysis of international river basins and hydro-political dependence of basin states, the only effort undertaken outside of the Oregon State University team, which is discussed below in more detail.

3. ‘For example, Egypt is listed as riparian to the Jordan, even though no perennial streams cross its boundary with Israel’ (Wolf et al., 1999, p. 426). ‘This definition, which we feel is the best available, does allow for one occasional inconsistency: If a basin is shared by only two nations, and all tributaries which cross the boundary are intermittent, we do not include it in the Register’ (Wolf et al., 1999, p. 426).

4. UNESCO’s International Groundwater Assessment Centre has been mapping all groundwater units shared by countries around the world (https://www.un-igrac.org).

5. The HydroBASINS ‘MOST-DOWN’ coding was used to merge nested sub-basins that drain to the same outflow.

6. This method was used to select distributaries in basins with deltas.

7. Some basins were edited for both holes, deltas and outlet inconsistencies, as well as slivers; the total percentage of edits in 310 basins does not count these basins twice, even if edited for multiple reasons.

8. The BCUs for disputed areas are coded using ‘/’ to separate country code, i.e., INDU_CHN/IND for the area in the Indus River Basin within the disputed Aksai Chin region between China and India. Notes in the tables denote which countries are administering these disputed areas.

9. Several of these historical data sets are available for download through the TFDD website at https://transboundarywaters.science.oregonstate.edu.

10. There are 150 countries with area in an international river basin; this increases to 157 if disputed areas are counted separately.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.