[01] Kenny Nyirenda, Department of Geology and Survey, Copperbelt University, Kitwe, Zambia. [02] Makaiko Nyirenda, Department of Geology and Survey, Copperbelt University, Kitwe, Zambia.

Understanding trends in extreme rainfall events is important in mitigating their impacts on socioeconomic sectors such as health, agriculture, water resources and the environment. In this study, historical trends in total annual precipitation and number of days with heavy precipitation events, their relationships and potential implications on the environment in Sub Sahara Africa were investigated. Gridded daily precipitation data from National Oceanic Atmosphere Administration (NOAA) with the spatial coverage of 0.50 - degree latitude x 0.50 - degree longitude grid (720x360) and temporal coverage from 1979 to 2018 were used. Mannkendall test was used to generate trends in days with heavy precipitation events (d95P) and total annual precipitation (prcptot) at 5% significance level. Trends in d95P and prcptot were then assessed and correlated to determine their relationships and potential impact on the environment. Results of the study indicate statistically significant decreasing trends in prcptot over Central Africa, the southern part of West Africa and in some parts of Southern Africa. Some pockets of significant increasing trends in prcptot were observed around Southern Africa, some parts of East Africa and the northern parts of West Africa. The largest portion of sub-Sahara Africa shows non significant trends in prcptot. Variable trends observed in prcptot could be attributed to regional differences in climate. In terms of d95P, significant decreasing trends are observed in Central Africa, South Central Africa and the southern parts of West Africa. Significant increasing trends in d95P events were observed in some parts of East Africa and some northern parts of West Africa. However, the magnitudes of these trends in terms of the Sen’s slope are minimal. Like prcptot, the largest parts of sub-Saharan Africa shows non significant trend in d95P. Trends in d95P and prcptot show a positive correlation. This indicates that the increase in d95P contributes greatly to the increase in prcptot over the base period. Regions which showed positive correlation between significant increasing trends in prcptot and d95P may be prone to flooding, landslides and related disasters. It should however be noted that most parts of sub-Saharan Africa indicate non significant trends in both prcptot and d95P at 5% significant level.

Precipitation, Extreme Events, Africa

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