Abstract
The Sahel region of West Africa is well known as a region of environmental degradation. The reported incidence of drought and desertification has been challenged but regional desiccation is still widely accepted. This paper investigates the evidence for regional desiccation and in particular the effect of aggregating rainfall statistics across the area. Regression analysis reveals that the recent regional downward trend in rainfall is not reproduced at all stations at the 1% level of significance but is significant when data is aggregated. Geostatistical methods were used to investigate the spatial variability of rainfall. The results suggest that changes in the raingauge network since 1945 rather than climate may be influencing regional rainfall statistics. It was found that the distribution of raingauges between 1945 and 1975 was not adequate to sample latitudinal changes in rainfall and that the annual rainfall for the region was largely a product of poor sampling east to west until sufficient stations were reporting data from 1970. These results raise questions over the use of regional statistics such as rainfall anomalies and the fitting of regional trend lines to depict climate change in the Sahel. Geostatistical methods offer a more complex but more reliable approach to the estimate of regional rainfall characteristics.
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Agnew, C.T., Chappell, A. (2000). Desiccation in the Sahel. In: McLaren, S.J., Kniveton, D.R. (eds) Linking Climate Change to Land Surface Change. Advances in Global Change Research, vol 6. Springer, Dordrecht. https://doi.org/10.1007/0-306-48086-7_2
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DOI: https://doi.org/10.1007/0-306-48086-7_2
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