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
sustainability of existing water resources supply; however, this model extends that capability to consider
feedbacks from one model component to another. The water model uses a physically based hydrologic
rainfall-runoff model, with surface and groundwater components, to produce monthly runoff and
groundwater recharge at the watershed scale. Surface runoff and recharge are the inflows into surface and
groundwater water reservoirs. The demographic sub model is a standard multi-cohort model that forecasts
the population by age, sex, rural, urban, education and hiv/aids status. The economic sub-model is a
computable general equilibrium model with three sectors: 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.