Using the Multiactor-Approach in Glowa-Danube to Simulate Decisions for the Water Supply Sector Under Conditions of Global Climate Change

Glowa-Danube (http://www.glowa-danube.de) is an interdisciplinary project that aims to develop integrated strategies and tools for water and land use management in the upper Danube catchment (Germany, Austria similar to 77,000 km(2)). The project is one of five within the Glowa research program (http://www.glowa.org) dealing with Global Change effects on the water cycle in six meso-scale catchments (up to 100,000 km(2)) in Central Europe, West Africa and the Middle East. In the Glowa-Danube project, 16 natural science and socio-economic simulation models are integrated in the coupled simulation system Danubia. This article describes the underlying concept and implementation of WaterSupply, a multiactor-based model of the water supply sector with a focus on water resource utilization and distribution of individual water supply companies. Within Danubia, WaterSupply represents the link between water supply and demand, where the former is simulated by a groundwater and a surface water model and the latter by water consumption models of four different sectors (domestic, industrial, agricultural and tourism). WaterSupply interprets the quantitative state of water resources for defined spatial and temporal units according to sustainability requirements and assesses the state of resources in relation to present water supply schemes and the dynamics of user demand. WaterSupply then seeks both to optimize the resource use of supply companies and to identify critical regions for which further adaptation of the water supply scheme will become necessary under changing climatic conditions. In this article, a brief description of the Glowa-Danube project and the integrated simulation system Danubia is followed by a short presentation of the DeepActor framework, which provides a common conceptual and technical basis for the socio-economic simulation models of Glowa-Danube. The main body of the article is devoted to the concept, the implementation and simulation results of WaterSupply. Results from different scenario calculations demonstrate the capabilities and the potential fields of application of the model.