Analysis of a Sahelian annual rainfall index from 1896 to 2000; the drought continues

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Abstract
Since 1970 the West African Sahel has experienced a significant drought which, according to some authors, corresponds to a discontinuity (abrupt change) in the rainfall series. An annual rainfall index was calculated over the period from 1896 to 2000, with a selection of 21 synoptic stations updated regularly by the Agrhymet Regional Centre in Niamey. Several statistical analyses of the index confirmed the previous descriptions, particularly the significance of the drought since 1970 and a nonstationarity, with abrupt change in the series between 1969 and 1970. Although the two recent wet years, 1994 and 1999, gave some hope of an end to the drought, the statistical results and the temporal distribution of the dry and wet years showed that the drought was not over at the end of 2000.