The expansion of irrigated croplands throughout the 20th century boosted global agricultural productivity, yet limited improvement occurred in sub-Saharan Africa where many irrigation schemes and policies under-delivered. We mapped the distribution of croplands under active irrigation between 1986 and 2020 for one of Africa’s largest and most important transboundary river basins—the Senegal River Valley; using Landsat imagery with a random forest classifier and hidden Markov Model. We document two distinct epochs of irrigation development. Initially, a period of stagnation where less than 900 ha yr⁻¹ was added, lasting until 2008. Followed by a boom phase of rapidly expanding intensively irrigated production with ∼9,000 ha yr⁻¹ added for the last 12 years. These epochs overlap with national agricultural policy frameworks: the 1980s laissez-faire policies limited state involvement in agriculture and promoted Asian imports; followed by a more interventionist period focused on promoting domestic production following the food price crisis of 2008.

Purpose: A food security indicator for technology impact assessment is needed that can be constructed with available data, is comparable over time and space, and represents the multiple dimensions of food security. Methodology/approach: In this chapter, we review some commonly used food security indicators, analyze the extent to which these indicators satisfy key criteria, and introduce a food security indicator constructed for use in an economic impact assessment and that exhibits a number of desirable properties. Findings: This income-based indicator is similar to a consumption-based poverty indicator, utilizing an estimate of the income required to purchase a food “basket” that meets nutritional requirements and comparing the food security income requirement to a household’s per capita income. Social implications: The applicability of the indicator is illustrated with an analysis of the impacts of legume inoculation technology developed for smallholder farms in Tanzania and other parts of Africa. We conclude with a discussion of suggested improvements for food security indicators used for technology impact assessment.

Water resource management in sub-Saharan Africa faces growing pressures from climate change, population growth, and rising competition over scarce water, especially in agricultural regions reliant on increasingly variable rainfall. While governments have long prioritized centralized management through formal irrigation schemes, informal farmer-led systems have become increasingly prominent. This study examines how institutional arrangements shape water governance by comparing water user associations (WUAs) in formal and informal irrigation schemes in Ghana's Upper East Region. Using Ostrom's design principles, and drawing on 160 interviews across 18 communities plus a participatory workshop, we analyse how different degrees of formalization influence infrastructure maintenance, community participation, and water allocation. Findings show that autonomy and external support are not opposing forces: support strengthens governance when it reinforces rather than replaces local decision-making. Infrastructure sustainability depends less on resource volumes than on alignment between governance structures and local maintenance capacities. Effective scaling requires retaining core elements of local autonomy while building targeted linkages to support institutions. We argue for moving beyond formal–informal dichotomies towards hybrid governance arrangements that combine state support with community-led management. These insights offer practical guidance for designing irrigation governance systems that enhance sustainability and equity in sub-Saharan Africa.