Policy exploration for Food-Energy-Water security at a city-regional level: an example in Cape Town, South Africa

Abstract:

Climate change is an issue that imposes unique challenges to regions around the globe. The accelerating rates of population increase and urbanization coupled with enhanced climate stresses make it ever-harder to achieve food-energy-water (FEW) security for societies. The challenges call for a change of the status quo in the current practices of FEW services as well as FEW policies. We develop a coupled human-natural system model (CHNSM) for Cape Town, South Africa, as a test-bed for the performance of various FEW resources management policies. The model comprises two parts, an agent-based model (ABM) and a hydrological model. The hydrological model calculates the available water of the reservoir system in Cape Town regions at each monthly time step. The ABM represents the FEW stakeholders, including wine producers, households with different income levels, business and industry, and a hydro-electric power dam, and it manages the water resources according to different policy specifications. We used the climate data from an ensemble of downscaled global climate models to simulate the CHNSM from 2009 to 2100. We designed several policies that included expanding the current capacity of the water supply system and restricting water use by controlling the demand by imposing price increases. The results suggest that Cape Town may face increasing water stress towards the next century, and the FEW stakeholders will need to reduce their water use significantly or the city will have to expand the capacity of the water supply system significantly. The model can be adapted to regions elsewhere around the globe.