Estimating the potential for expanding smallholder irrigation in Sub-Saharan Africa

•We assess expansion potential of smallholder irrigation in Sub-Saharan Africa.•An integrated biophysical-economic modeling system is developed for the assessment.•Sub-Saharan Africa has a large potential for smallholder irrigation expansion.•Expansion of smallholder irrigation is limited by water scarcity in many regions. Smallholder irrigation may considerably contribute to agricultural productivity growth in Sub-Saharan Africa. However, the full potential of expanding smallholder irrigation under alternative irrigation technologies is not known. This paper presents a study to assess the irrigation expansion potential for four smallholder irrigation technologies: motor pumps, treadle pumps, communal river diversion, and small reservoirs. An integrated modeling system that combines GIS data analysis, biophysical and economic predictive modeling, and crop mix optimization techniques was developed for the assessment. The study revealed a large potential for profitable smallholder irrigation expansion in Sub-Sahara Africa. Area expansion potential is 30millionha for motor pumps, 24millionha for treadle pumps, 22millionha for small reservoirs and 20millionha for communal river diversions. The technologies can benefit between 113 and 369 million rural people in the region generating net revenues of US $ 14–22billion/yr, depending on technology. Final expansion potential depends on irrigation technology cost and commodity price developments.