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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 Delphine Digout, UNEP/GRID-Arendal)
Source(s)
Igor A. Shiklomanov, State Hydrological Institute (SHI, St. Petersburg) and United Nations Educational, Scientific and Cultural Organisation (UNESCO, Paris), 1999.
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Uploaded on Saturday 25 Feb 2012
by GRID-Arendal
Long-term variations in river flow, by continent
Year:
2005
Author:
Delphine Digout, UNEP/GRID-Arendal
Description:
River runoff is cyclical in nature, with alternating cycles of wet and dry years. Significant deviations from average values differ in duration and magnitude. For example, 1940-44, 1965-68 and 1977-79 are clearly low periods in terms of total runoff from the world's rivers. During these periods, the runoff was estimated at 1 600-2 900 km3 below the average value. By contrast, 1926-27, 1949-52 and 1973-75 saw much greater levels of river runoff (Shiklomanov, 1999). The last two decades have witnessed increasing runoff in South America and decreasing runoff in Africa.
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