Why invest in minor projects in sub-Saharan Africa? An exploration of the scale economy and diseconomy of irrigation projects

  • Hitoshi Fujiie
  • Atsushi Maruyama
  • Masako Fujiie
  • Michiko Takagaki
  • Douglas J. Merrey
  • Masao Kikuchi


It is well-known that major irrigation projects have a strong scale economy, handicapping irrigation development in sub-Saharan Africa (SSA) because of the difficulty in formulating large-scale projects. Using project-level investment cost and performance data of major and minor irrigation projects, this paper examines the causes of the economy of scale phenomenon. We find that strong scale economy exists not only for major but also for minor projects, i.e., small- and micro-scale, projects. This is largely because of the existence of indivisible overhead costs such as high-opportunity-cost human resources for planning, designing and engineering management and supervision. We also find that large differences between major and minor projects in the absolute level of overhead as well as construction costs creates a strong scale diseconomy and results in better performance of minor projects. The advantage of minor projects holds even when their higher risk associated with the water source is taken into consideration. We argue that there is an urgent need to promote irrigation development in SSA through developing minor projects, and to reduce the heavy burden of overhead costs by developing the capacity of human resources at the national, local and farmer levels in the fields of irrigation engineering, irrigation agronomy, institutional development, and micro water management technologies.


Construction cost Irrigation development Overhead cost Performance Scale economy Sub-Saharan Africa 



This study was supported by JSPS Science Research Fund (KAKENHI No.19405046). We are grateful to the JICA Uganda Office for allowing us to have access to the data on small and minor scale irrigation projects.


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Hitoshi Fujiie
    • 1
  • Atsushi Maruyama
    • 2
  • Masako Fujiie
    • 2
  • Michiko Takagaki
    • 2
  • Douglas J. Merrey
    • 3
  • Masao Kikuchi
    • 2
  1. 1.Japan International Cooperation AgencyChiyoda-kuJapan
  2. 2.Chiba UniversityKashiwaJapan
  3. 3.PittsboroUSA

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