Using this graphic and referring to it is encouraged, and please use it in presentations, web pages, newspapers, blogs and reports.
For any form of publication, please include the link to this page and give the cartographer/designer credit (in this case Philippe Rekacewicz, UNEP/GRID-Arendal)
Shiklomanov I. A., World Water Resources: Modern Assessment and Outlook for the 21st Century, 1999. (Summary of World Water Resources at the Beginning of the 21st Century, prepared in the framework of the IHP UNESCO). Federal Service of Russia for Hydrometeorology & Environment Monitoring, State Hydrological Institute, St. Petersburg.
Uploaded on Saturday 25 Feb 2012
River runoff by continent, 1921-1985
Philippe Rekacewicz, UNEP/GRID-Arendal
River runoff represents the accumlated water, from preciptation and meltwater, that feeds into rivers that feeds into seas. The estimated annual figures in this graphic is what volume of water that ends up in the World Ocean. Factors influencing this volume is primarily the area that drains (e.g. area of continent), precipitation and evaporation. Tropical regions typically exhibit greater river runoff volumes. The Amazon carries 15% of all the water returning to the world's oceans, while the Congo-Zaire basin carries 33% of the river flow in Africa. Arid and semi-arid regions, which make up an estimated 40% of the world's land, have only 2% of its runoff (Gleick, 1993).