Implementing the water–energy–food nexus through tools and scenario planning: a case study approach for southern Africa.

Abstract

To develop tools and avail evidence for promoting implementation of the integrated transformative water-energy-food (WEF) nexus approach in southern Africa, this study assessed the status of existing WEF nexus tools, developed and applied a WEF nexus analytic tool, and developed a WEF nexus scenario-based methodological framework and guidelines. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol was used to review literature on the status of existing WEF nexus tools. Despite the relative abundance (46 by 02 of July 2021) of reported WEF nexus tools, the broader accessibility, uptake, and utility of their majority (61%) is limited by their unavailability and limited functions. The geospatial web-based and Analytic Hierarchy Process (AHP)-based integrative analytical tool for the WEF nexus (the iWEF) was developed using digital tools, and calibrated and validated with existing tools and data at varying spatio-temporal scales. The iWEF model was used with inputs (pairwise comparison matrices, PCMs) from key WEF-related expert stakeholders to assess the state of WEF nexus and implementation of the approach at subnational scales in southern Africa, specifically Inkomati-Usuthu Water Management Area and Ehlanzeni District Municipality (South Africa) and Mzingwane Catchment and Umzingwane District (Zimbabwe). It was found that the state of the WEF nexus is moderately sustainable in Inkomati-Usuthu Water Management Area, Ehlanzeni District Municipality, Mzingwane Catchment and Umzingwane District due to suboptimal integrated WEF nexus composite indices (maximum = 0.286) of 0.209, 0.210, 0.189 and 0.194, respectively. This is due to the unbalanced management and insecurity of WEF resources that is apparent in the two catchments and two ditsricts. Mining for coal (South Africa) and gold (Zimbabwe) and climate change threatens the WEF nexus in the four studied areas. Using evidence from literature review and input from key WEF-related expert stakeholders, and established framework development protocols, this study developed, refined and validated generic people-centred and data-informed methodological framework and guidelines for co-developing integrated WEF nexus scenarios. In conclusion, the majority of relatively abundant WEF nexus tools are fraught with functional limitations and the iWEF tool is reliably applicable across multiple scales. Implementation and state of the WEF nexus approach is moderately sustainable in southern Africa and the developed methodological framework and guidelines for co-developing integrated WEF nexus scenarios are robust. This study recommends the demand-driven improvement of the iWEF tool, and methodological framework and guidelines, and their application in case studies to facilitate implementation of the WEF nexus approach towards robust and resilient WEF systems.