A recent review of irrigation projects in sub-Saharan Africa found some surprising reasons for the poor performance of many schemes that complement the usual suspects (McCarthy and Winters, 2022). Not only is irrigation infrastructure itself often poorly constructed (not "fit"), but the operations, maintenance and repair of irrigation infrastructure is often too costly given irrigators' profitability (not "fit for purpose").

Our review confirmed the findings of many others on the factors that are critical in determining the success (or lack thereof) of surface water irrigation schemes. These include issues related to tenure security; transaction costs of collective action; adequacy of capacity building of scheme management at all relevant administrative levels; and presence of a clear legal and regulatory framework that clarifies the roles and responsibilities of different stakeholders (e.g., government irrigation authorities, parastatals or private sector firms, water user associations [WUAs], and irrigators). Underlying hydrogeological and climate characteristics can also affect success; though evidence is scarce, incentives to maintain schemes seem generally higher where rainfall is relatively low, but irrigation water supply is relatively stable.

Starting with schemes that are not fit, there are numerous examples of poor-quality construction, including improperly placed intake valves (leading either to no irrigation at all or no irrigation in the dry season), improper drainage, the use of poor-quality materials, and instances where construction was simply never completed. Years ago, I led a project on small-dam irrigation schemes in northern Ghana and observed multiple construction defects in the small set of schemes that did function (it is likely that even more defects would have been found at completely defunct schemes). The number of observations was too small to draw more than tentative hypotheses on why. But out of 19 schemes rehabilitated or constructed between 2000 and 2005, by 2007, seven were not completed (mainly irrigation and drainage canals not finished or even constructed), and at six sites, water levels were too low to reach the intake valve (the latter was likely due to both poor construction and sedimentation) (Birner et al., 2010).

The widespread nature of shoddy construction was still a surprise 15 years later. Some construction problems are related to poor design, stemming from poor and/or rushed project proposals. However, other problems are related to lack of capacity to secure competent contractors and supervise construction. These problems arise with many large-scale infrastructure projects; but many problematic irrigation schemes are relatively modest in size. Evidence also suggests that the largest scale schemes are less likely to suffer from design and supervision problems, probably because higher quality services are contracted. It appears, then, to be more than just the standard large-infrastructure-related problems that afflict these schemes.

Contracting and supervision problems appear to have defied all attempts at mitigating them, from transferring supervision from national government irrigation authorities to local irrigation offices, to third party experts, to local administrative authorities, and even to irrigators themselves (the latter two presuming that supervision does not require much construction and engineering expertise). A recent study by Keita et al. (2022) documents the failures of an internationally funded NGO project that constructed micro-irrigation schemes (well-based systems to irrigate one hectare). The authors attribute significant failure of the project to poor engineering choices. But it may also be because the NGO simply did not have the expertise to choose feasible designs, did not itself possess the expertise to supervise construction, and did not have sufficient donor funding to hire experts. Unanswered questions remain, such as: how does the poor quality of built schemes affect the incentives of irrigators to participate in maintenance activities and pay fees? Are there negative impacts of scheme failure on future efforts to engage in collective action for irrigation?

The second surprise is even more prevalent, though difficult to disentangle from other problems mentioned above. A lot of evidence suggests that, even if schemes are well-built and the management team has all the necessary skills, irrigators simply do not realize sufficient returns to afford costs associated with operations and management. They are not fit for purpose. In the case of South Africa, evidence suggests that irrigation schemes with sophisticated sprinkler systems were well built, but the rapid and chaotic Irrigation Management Transfer (IMT) process led to swift declines in many systems. Researchers attribute this to limited or no attention to the management skills needed by the newly established WUAs, but also to the fact that smallholders focused on subsistence crops simply could not afford fees associated with sustainable operation and maintenance. Similarly, IMT in Zimbabwe entailed transferring all scheme costs to WUAs, including the pumping fuel costs that had been primarily borne by the government. Successful transfer was premised on the hypothesis that smallholders would quickly switch to high-value crops, which simply did not materialize. Other examples abound.

Relatedly, many irrigation project proposals base their expected economic benefits on unrealistic and overly optimistic assumptions on the adoption of high-value cropping, market transaction costs, and input costs (Inocencio, et al., 2007; Fujiie et al., 2011; Molle and Renwick, 2005; Higgenbottom et al., 2021). Smallholder irrigators often face limited integration into value chains, even if they can aggregate their production. And yet, proposal after proposal assumes that small irrigators will magically adopt high-value crops, or that value chains can easily be developed in tandem with irrigation construction. Proposal after proposal keeps setting the conditions for smallholders to invest time and resources into irrigation infrastructure that is doomed to fail. As with irrigation infrastructure that is not fit, building not fit for purpose schemes may have additional negative impacts on future efforts to engage in collective efforts for irrigation and even other resilience building activities.

Climate change has spurred renewed interest in irrigation schemes to build resilience, but there is limited evidence that project proposers are incorporating lessons from a substantial empirical evidence base. And the evidence suggests all aspects of irrigation projects are subject to flaws, from initial design to scheme management transfer, and every step in between.


References

Birner, R., McCarthy, N., Robertson, R., Waale, D. and Schiffer, E.2010. Increasing access to irrigation: lessons learned from investing in small reservoirs in Ghana. Paper presented at the Agricultural Services, Decentralization, and Local Governance Workshop, June 3, 2010, Accra.Washington DC: IFPRI.

Fujiie, H., Maruyama, A., Fujiie, M., Takagaki, M., Merrey, D. J., and Kikuchi, M. 2011. Why invest in minor projects in sub-Saharan Africa? An exploration of the scale economy and diseconomy of irrigation projects. Irrigation and Drainage Systems, 25(1): 39-60.

Higginbottom, T. P., Adhikari, R., Dimova, R., Redicker, S., and Foster, T. 2021. Performance of large-scale irrigation projects in sub-Saharan Africa. Nature Sustainability, 4(6): 501-508.

Inocencio, A., Kikuchi, M., Tonosaki, M., Maruyama, A., Merrey, D., Sally, H., and de Jong, I. 2007. Costs and performance of irrigation projects: A comparison of sub-Saharan Africa and other developing regions. IWMI Research Report 109. International Water Management Institute, Colombo, Sri Lanka. 

Keita, A., Niang, D., and Sandwidi, S.A. 2022.How non-governmental organization-built small-scale irrigation systems are a failure in Africa.Sustainability, 14(18): 11315.

McCarthy, N. and Winters, P.C.2022.Building resilience to climate change in Sub-Saharan Africa through irrigation investments.Pulte Institute Policy & Practitioner Report No. 4.South Bend, IN: University of Notre Dame.  https://pulte.nd.edu/research-policy/visiting-associates-program-publications/nancy-mccarthy/

Molle, F. and Renwick, M.2005. Economics and politics of water resource development: The case of the Walawe River Basin, Sri Lanka. IWMI Research Report 87. International Water Management Institute, Colombo, Sri Lanka.

Photo Credit: Jean-Philippe Venot / Burkina Faso