Recent Rainfall Changes in Central Sudan and Their Physical and Human Implications

This paper examines rainfall changes and their physical and human implications in the critical 'desertification zone' between latitudes 12'N and 160N of the Democratic Republic of the Sudan. Three aspects of rainfall change are examined: changes in annual rainfall (the primary parameter), changes in daily rainfall magnitude-frequency, and rainfall localization (secondary parameters). Graphical and statistical analyses of 26 long-term annual rainfall series highlight the existence of distinct wet and dry sequences, although suggesting that these fall within the expectations of random series. Changes in daily rainfall frequencies of magnitudes > 10 mm broadly follow annual rainfall. Rainfall localization is shown to occur on scales from 48 hours to up to 5 years. The implications of these rainfall characteristics are discussed quoting examples from the White Nile region of central Sudan. Evidence suggests that secondary rainfall parameters are of greater consequence for land use changes and human activities than are annual rainfall totals alone.