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

Abstract

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.

Assessing Performance of Small‐Scale Pumped Irrigation Systems in sub‐Saharan Africa: Evidence from a Systematic Review

“…The increased use of SSI pumped systems in SSA has been established on the grounds that larger‐scale irrigation schemes have often failed (Fujiie et al, ). It is believed that pumped systems are among the simple technologies that enable smallholder farmers to access water from sources that may not be possible with gravity.…”

“…The search period was limited to studies published between 1990 and 2013 based on indications of increased interest in SSI development in Africa (Baba, ; Fujiie et al, ). The search used trials in Scopus and finally two search strings (Irrigat* pump* AND Agricultur*) and (Irrigat* Pump* OR Water management OR Irrigat* technolog*'' AND (Smallholder* OR Farmer* OR Grower* OR Rural Communit* OR Household*) were used to search all relevant scientific databases (Scopus, Science Direct, Web of Knowledge, Environmental Complete and Direct Access Journals), organization websites (e.g.…”

“…We argue here that evidence on performance of SSI pumped systems can only be obtained if the key drivers are identified and their measurement standardized. Although studies (Kimmage and Adams, ; Namara et al ., ; Fujiie et al, ; Daccache et al , ) have attempted to review the performance of irrigation development in SSA, no systematic review (SR) has been undertaken on small‐scale pumped irrigation development. We contribute to addressing this gap in knowledge by applying an SR approach to synthesize published science and grey evidence to identify the key factors affecting performance of SSI pumped systems and use the evidence to inform policies promoting SSI pumped systems in SSA.…”

Business model scenarios and suitability: smallholder solar pump-based irrigation in Ethiopia. Agricultural Water Management – Making a Business Case for Smallholders

“…Research now suggests that there is significant potential for expanding small-scale irrigation to contribute to local and national food security, improved nutrition (Domènech 2015) and income generation (Namara et al 2010;Dillon 2011;Burney and Naylor 2012). One study proposed the scope for expanding small-scale irrigation in Africa to be 7.3 million hectares (Mha), with internal rates of return much larger for small-scale than for largescale, dam-based irrigation (You et al 2010), an argument supported by Fujiie et al (2011).…”

Successful small-scale irrigation or environmental destruction? The political ecology of competing claims on water in the Uluguru Mountains,Tanzania

“…In recent years, there has been a revived interest in support to irrigation schemes, including the rehabilitation of earlier failures (Mwendera and Chilonda 2013;Veldwisch et al 2009). Meanwhile the unfulfilled potential of small-scale irrigation to contribute to the transformation of agriculture is SSA has been stressed increasingly (Fujiie et al 2011;Kadigi 2012;Sakagi and Koga 2011). A…”