Dryspell frequency and trends over time in semi-arid and dry sub-humid sub-Saharan Africa : Implictions for smallholder farmers

• Small-scale farmers in semi-arid and dry sub-humid sub-Saharan Africa (SSA) are vulnerable to dryspells, a primary reason for agricultural droughts. We used large-scale publicly available datasets to analyze frequency and trends over time in dryspells of critical length for farmers. 54 rainfall stations across the croplands of semi-arid and dry sub-humid SSA were included. Results show that stations with long-term seasonal rainfall averages below 600 mm experience critical dryspells in more than 60% of their seasons, whereas the corresponding figure for stations with averages above 600 mm is 40% or less. Almost every season is affected by dryspells for stations below 400 mm. Further, dryspell seasons are often affected by multiple dryspells. Most stations do not show any trends of changing dryspell frequency. Among the 21 stations that do exhibit changes over time, 19 have been subjected to an increasing trend, and only 2 to a decreasing trend. For six stations the increase is statistically significant. We conclude that frequent dryspell seasons with multiple dryspells, is a reality of rainfed farming systems, especially in semi-arid SSA. Efforts to increase productivity in these systems must include strategies to manage dryspells to be effective. The publicly available data contains large gaps that restrict the analysis. This is highly problematic, particularly given the fundamental importance of rainfall dynamics for livelihoods in the poorest regions of the world.

Nyckelord

rainfall variability

dryspells

agricultural droughts

growing season

smallholder farmers

yield impact

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vet (ämneskategori)

ovr (ämneskategori)