Water-Resource Assessments of Basins within Developed and Developing Countries: The Role of Regional Climate Uncertainty, Policy, and Economics

The fate of natural and managed water resources over any basin are controlled to varying degrees by energy, agricultural, municipal, and environmental systems, which are linked together as well as to the hydro-climate cycles. The growing need for risk-based assessments of impacts and adaptation to regional climate change calls for the quantification of the likelihood of these regional outcomes through the representation of their uncertainty - to the fullest extent possible. A hybrid approach that extends the MIT Integrated Global System Model (IGSM)framework to provide probabilistic projections of regional climate changes is presented. This procedure constructs meta-ensembles of the regional hydro-climate, combining projections from the MIT IGSM that represent global-scale uncertainties with regionally resolved patterns from archived climate-model projections. From these, a water-system management module tracks water allocation and availability across competing demands from irrigation, cooling for thermoelectric generation, hydropower, municipal, mining and industrial sectors.

Our collaborative investigation assesses the fate water resources and their economic impacts due to shifts in hydro-climate, and considers water basins over the United States and southern Africa. Special attention is given to distinctions between how developed and developing nations' water management factors must be accounted within this integrated framework. In particular, factors controlling withdrawal and consumption for irrigation over the U.S. can involve econometric considerations, where crops in some regions are more/less favored for irrigation due to their high/low commodity value. In contrast, damages to transportation infrastructure from extreme events can impose more egregious, considerable economic damages to economic growth and productivity for developing nations. The integrated impacts of these mechanisms are quantified through frequency distributions of changes in water stress (or availability) and economic productivity (i.e. GDP shocks), and we present results from a suite of simulations that consider a range of global climate-change policies aimed to stabilize (or not) concentrations of greenhouse gas concentrations by the end of this century.