Rainfall trends in West Africa, 1901-1985

Abstract

This paper attempts to examine the characteristics of rainfall variations between 1901-1985 in West Africa using instrumental records. It discusses the characteristics of rainfall, particularly, periodicities and variabilities, emphasizing decadal, quinquennial and annual characteristics. The paper also discusses some hydroclimatologic consequences of climatic change and climatic variations with respect to streamflow characteristics. From the various analyses, it was observed (a) that the present century began with a relatively long period of drought persistence (1900-1926). This was followed by a wet period which lasted between 1927-1960; (b) that the present drought conditions have been characteristically persistent since about 1961 and particularly since about 1965; (c) that in spite of the above generalizations, no regular patterns can be observed in trends, periodicities and persistence of hydrologie consequences of rainfall variations to allow for predictability of these consequences in relation to rainfall variations; and (d) that because of the large spatial and temporal variations in the characteristics of rainfall, and the resulting hydroclimatologic consequences, there is urgent need to improve the availability and reliability of the data. Note: A French abstract of this paper can be found at the end of the text.