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[1] A method is described for the generation of multivariate stochastic climate sequences for the Berg and Breede Water Management Areas in the Western Cape province of South Africa. The sequences, based on joint modeling of precipitation and minimum and maximum daily temperatures, are conditioned on annualized data, the aim being to simulate realistic variability on annual to decadal time scales. A vector autoregressive (VAR) model is utilized for this purpose and reproduces well those statistical attributes, including intervariable correlation and serial autocorrelation in individual variables, most relevant for the regional climate in this setting. The sequences incorporate nonlinear climate change trends, inferred using an ensemble of global climate models from the Coupled Model Intercomparison Project (CMIP5). Subannual variability is simulated using a block resampling scheme based on the k-nearest-neighbor approach, preserving both temporal patterns and spatial correlations. Downscaling to a network of quinary-level catchments enables distributed runoff, streamflow, and crop simulations and the assessment and integration of impacts. Final output takes the form of daily sequences, structured for driving the ACRU agrohydrological model of the University of KwaZulu-Natal, South Africa.

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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. 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 hydrologic 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, andHIV/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.