Supporting sustainable water policy
Climate change and growing demand mean that competition for scarce water resources is increasing worldwide. The consequences for the environment and the global economy could be severe. The Global Hydro-economic Model, currently under development by the IIASA Water Program, can be used to simulate a wide range of possible future scenarios, supporting policymakers to create cost-effective, long-term sustainable water management policies.
The pressure on water resources has been mounting worldwide, with water scarcity becoming a widespread problem in most arid and semiarid regions around the world. Global water extractions have increased more than six fold in the last century, which is more than twice the rate of human population growth . However, the impact of growing water scarcity on long-term sustainable development has not been adequately addressed by the integrated assessment research community.
Specifically, the allocation of water resources across regions and sectors at the global level remains largely unaccounted for in long-term modeling. To reconcile potential inconsistencies introduced by constraints on future water availability, IIASA researchers are developing the Global Hydro-economic Model, which will integrate spatially distributed water resource systems, infrastructure, management options, and economic values. In addition, it will be possible to link it with other IIASA integrated assessment models: the Community Water Model; the Model for Energy Supply Strategy Alternatives and their General Environmental Impact; and the Global Biosphere Management Model.
The Global Hydro-economic Model uses optimization to balance global water demand and supply at the level of large-scale river basins. The technique allows the model to minimize the total costs of meeting the water demands from the agricultural, industrial (energy and manufacturing), and domestic sectors, while also taking into account various resource, institutional, and environmental constraints, such as retaining enough water for healthy aquatic ecosystems.
Monthly variation will be included so the model can align with existing IIASA integrated assessment models. The model can be used to simulate a variety of basin management decisions including resource extractions, interbasin transfers, reservoir storage, and water infrastructure investment (i.e., the choice of the size and location of new water projects). The model uses information on water demand and availability provided by existing global integrated assessment models at IIASA and provides information on water resources development and allocation to those models.
The proposed integration of the Global Hydro-economic Model with other IIASA integrated assessment tools.
The development of the Global Hydro-economic Model, which involves several different programs at IIASA (the Water, Energy, and Ecosystem Services and Management programs) is carried out as part of the larger Integrated Solutions for Water, Energy, and Land project.
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 Kahil MT, Ward F A, Albiac J, Eggleston J, & Sanz D (2016). Hydro-economic modeling with aquifer-river interactions to guide sustainable basin management. Journal of Hydrology 539: 510-524.
 Kahil TM, Ward FA, Albiac J, Eggleston J, & Sanz D (2016). Hydro-economic modeling of conjunctive ground and surface water use to guide sustainable basin management. In: European Geosciences Union (EGU) General Assembly 2016, 17–22 April 2016, Vienna, Austria.