Population growth, meat-focused diets and emerging industries are increasing stress on water, energy and food (hereafter: WEF) supply around the globe. As stress on the resources rises, the interdependencies between the sectors become more apparent and often lead to unforeseen chain reactions. An example of which is: a drought leads to disappointing hydropower generation that leave groundwater pumps inoperable, which in turn lead to disappointing harvests.

Because of these chain effects, synergizing water, food, and energy policy is no easy task. Unconnected institutional entities further complicate this. Farmers are promoted to grow water intensive rice while at a nearby city faces a drinking water crisis.
Sustainability regulations encourage the replacement of food crops by biofuel crops while elsewhere forests are cut to make place for food production.

The ‘Nexus’, that is an acronym for the interrelated WEF system, and the need to obtain integrated policies was globally advocated. Several analytical Nexus models where developed but left a lot to be desired according to critics. The main critique of these models so far has been that many cannot serve as a
decision support tool because they lack the ability to investigate specific governance actions or the implementation of technical interventions. These models generally have intensive data requirements and are not scalable and flexible enough to perform for many Nexus studies within a single model framework.

In this study an optimization model framework is proposed, titled ‘MAXUS’, specifically designed to address the shortfalls of current models. It was built to customize a model for a specific Nexus study. To test the methodology of MAXUS it was applied to a case study for Ghana and Burkina Faso. Allocation of water and land resources for the final supply of WEF was optimized over space and time, for the objective and constraints given.
It demonstrates how sectors could respond in harmony to changes occurring in one of the sectors. The model shows non-trivial, multi-sectoral, spatial and temporal trade-offs for operational management and infrastructural planning of WEF sectors. For example, changing locations of proposed irrigation capacity because of an increase in electricity demand.

Moreover, the case study demonstrated how it can support in decision making on cross-border cooperation by means of separate optimization for Ghana and Burkina Faso. It showed how sharing resources and open trade would lead to a large reduction in infrastructural requirements. In case of non-cooperation, it
would be beneficial for Burkina Faso to expand reservoir storage capacity and irrigation capacity on a much larger basis than in case of cooperation. Mainly because it would not benefit from hydropower production generated in Ghana in case of noncooperation.
It also showed how thermal power production would have to fill up the gap in electricity supply and how food imports would need to compensate for the loss in food production.

MAXUS is built to serve in a wide range of nexus studies. Hence, it is scalable in time and space, has an adaptable data structure and allows customization of objectives, balances, constraints dimensions and decision variables.

Using Maxus to customize a model for a specific cases study requires broad expertise. It requires engineers to set-up the equations for the model, experts in different sectors that understand the interactions, and local experts that now the
conditions that apply in the case study area. Furthermore, it demands policymakers to think through their ambitions, their preferences, their range of possible interventions and governance actions, and the influences of their decisions on each of the WEF sectors. Exploring strategies for responding to developments in the WEF sectors requires cooperation of all sectors.