The state of the water-energy-food nexus at sub-national scales in southern Africa: the case of South Africa and Zimbabwe

Despite repeated commitments to universal access to water, energy, and food, most developing countries continue to face challenges to the security of these strategic resources and struggle to achieve the related Sustainable Development Goals (SDGs 2, 6, 7). We assessed the state of the water-energy-food (WEF) nexus at sub-national scales in South Africa (Inkomati Usuthu Water Management Area) and Zimbabwe (Mzingwane Catchment), employing a mixed-methods approach that included (i) a literature review, (ii) stakeholder engagement, (iii) observations and (iv) modelling. The key inputs in the iWEF tool were pairwise comparison matrices (PCMs) developed from key WEF-related expert stakeholders’ pairwise judgements of the six iWEF model indicators. Inkomati Usuthu Water Management Area and Mzingwane Catchment had WEF nexus composite indices of 0.209 and 0.189, respectively, indicating that the management of WEF resources is moderately sustainable. The irregular shape of the centrepieces in the spider diagram in the iWEF tool is symptomatic of an overall imbalance in the management of WEF resources in the Inkomati Usuthu Water Management Area and the Mzingwane Catchment. These findings provide entry points for prioritised interventions to improve resource security. Still, these should be planned and implemented from a nexus perspective to optimise synergies and minimise trade-offs and risks. With the two case studies located in arid and water-scarce regions, opportunities for improving WEF security lie in managing available resources from a nexus perspective. Decentralised and off-grid solutions should also be considered, especially in rural areas where most of the population lives in the Inkomati Usuthu Water Management Area and the Mzingwane Catchment. To conclude, southern African countries share a similar history, context, and WEF-related developmental challenges. It can be inferred that their sub-national scales are in moderately sustainable states of the WEF nexus, which require nexus planning for integrated, contextualised solutions to improve collective WEF security for all.