Development of a modelling framework to analyze the interrelations between the water, energy and food systems in the Zambezi River Basin

Analyses for water infrastructure investment planning must consider the interdependencies of local and regional water, energy, food, and environmental systems. This highly complex decision problem requires decision support tools to objectively determine the multi-sector economic value of investments while accurately modelling the competition among the sectors for water, land, labour, and capital resources. We employ an open-source hydroeconomic optimization model, What-if, which represents the water, agriculture, and power systems in a holistic framework. We apply the methodology to the Zambezi River Basin, a major African basin shared by eight countries, the regional agriculture system of southern Africa (SADC), and the Southern African Power Pool. We show that the value of the hydropower development plan is sensitive to future fuel prices, carbon pricing policies, the capital cost of solar technologies, and climate change. Similarly, we show that the value of the irrigation development plan is sensitive to the evolution of crop yields, world market crop prices and climate change. Additionally, renewables might significantly impact the power market, but this will have little effect on the agriculture system in the Zambezi River Basin. Trade-offs between agriculture, hydropower and ecosystems are limited under the current climate. But under dry climate change scenarios, prioritizing the hydropower production can generate mild adaption benefits for the power system but results in very large losses for irrigated agriculture while rainfed agriculture and ecosystems also suffers.