An integrated population-economic, and water resource model to address sustainable development questions for Botswana

An integrated population, economic, and water resource-model was developed to address sustainable development questions for Botswana. Traditionally, water resources planning models have considered the implications of different assumptions of population and economic growth on the sustalnablllty of existing water resources supply; however, this model extends that capability to consider feedbacks from one model component to another. For example, the model has the unique capability to examine implications of changing water-related diarrhea incidence on the health of the HIV/AIDS population. Investments In water supply and sanitation or In HIV/AIDS medication impact the health and productivity of the population. The water model uses a physically-based hydrologie rainfall-runoff model with surface and groundwater components to produce monthly runoff and groundwater recharge at the watershed scale. Botswana is divided into socioeconomic regions, and the water resources infrastructure is characterized by virtual reservoirs in each. The demographic sub-model is a standard multicohort model that forecasts the population by age, sex, rural or urban residence, education level, and HIV/AIDS status. The economic sub-model is a computable general equilibrium model with three components: agriculture, non-agricultural exports, and non-tradables. The model runs an ensemble of scenarios, including climate change, HIV/AIDS, health, economic, and water conservation scenarios, whose output is probabilistic in nature. The three model components are described, with particular emphasis on the model linkages and the water sub-component, and results are shown for a variety of scenarios.