The research project GLOWA-Danube, financed by the German Federal Government, is investigating long-term changes in the water cycle
of the upper Danube river basin (77,000 km
2) in light
of global climatic change. Its aim is to build a fully integrated decision-support tool “DANUBIA” that combines the competence
of 11 different research
institutes in domains covering all major aspects governing the water cycle—from the formation
of clouds, to groundwater flow patterns, to the behaviour
of the water consumer. Both the influence
of natural changes in the ecosystem, such as climate change,
and changes in human behaviour, such as changes in l
and use or water consumption, are considered. DANUBIA is comprised
of 15 individual disciplinary models that are connected via customized interfaces that facilitate network-based parallel calculations. The strictly object-oriented DANUBIA architecture was developed using the graphical notation tool UML (Unified Modeling Language)
and has been implemented in Java code. All models use the same spatial discretisation for the exchange
of data (1 × 1 km grid cells) but are using different time steps. The representation
of a vast number
of relevant physical
and social processes that occur at different spatial
and temporal scales is a very dem
anding task. Newly developed up-
and downscaling procedures [Rojanschi, V., 2001. Effects
of upscaling for a finite-difference flow model. Master’s Thesis, Institut für Wasserbau, Universität Stuttgart, Stuttgart, Germany]
and a sophisticated time controller developed by the computer
sciences group [Hennicker, R., Barth, M., Kraus, A., Ludwig, M., 2002. DANUBIA: A Web-based modelling
and decision support system for integrative global change research in the upper Danube basin. In: GSF (Ed.), GLOWA, German Program on Global Change in the Hydrological Cycle Status Report 2002. GSF, Munich, pp. 35–38; Kraus, A., Ludwig, M., 2003. GLOWA-Danube Papers Technical Release No. 002 (Danubia Framework), S
oftware-Release No.: 0.9.2, Documentation Version: 0.10, Release Date: 27 March 2003] are required to solve the emerging problems. After a first successful public demonstration
of the DANUBIA package (nine models) in May 2002 [Mauser, W., Stolz, R., Colgan, A., 2002. GLOWA-Danube: integrative techniques, scenarios
and strategies regarding global change
of the water cycle. In: GSF (Ed.), GLOWA, German Program on Global Change in the Hydrological Cycle (Phase I, 2000–2003) Status Report 2002. GSF, Munich, pp. 31–34], the research consortium is now preparing a first validation run
of DANUBIA for the period 1995–1999 with all 15 models. After successful completion
of the validation, a scenario run based on IPCC climate scenarios [IPCC, 2001. Climate Change 2001: Synthesis Report. In: Watson, R.T., Core Writing Team (Eds.), A Contribution
of Working Groups I, II,
and III to the Third Assessment Report
of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK
and New York, NY, USA, 398pp] for a five year period between 2025
and 2040 will follow at the end
of 2003.
The research group “Groundwater and Water Resources Management” at the Institute of Hydraulic Engineering, Universität Stuttgart, is contributing both a three-dimensional groundwater flow model of the catchment and an agent-based model for simulating water supply and distribution. This paper gives a general overview of the GLOWA-Danube project and describes the groundwater modeling segment. Nickel et al. deal with the water supply model in a second contribution to this special issue.
A three-dimensional numerical groundwater flow model consisting of four main layers has been developed and is in a continual state of refinement (MODFLOW, [McDonald, M.G., Harbaugh, A.W., 1988. A modular three-dimensional finite-difference ground-water flow model: US Geological Survey Techniques of Water-Resources Investigations, Washington, USA (book 6, Chapter A1)]). One main research focus has been on the investigation of upscaling techniques to meet the requirement of a fixed 1 × 1 km cell size. This cell size is compulsory for all models in DANUBIA in order to facilitate a one to one parameter exchange. In a second stage, a transport model (nitrogen) will be added (MT3D: [Zheng, C., Hathaway, D.-L., 1991. MT3D: a new modular three-dimensional transport model and its application in predicting the persistence and transport of dissolved compounds from a gasoline spill, with implications for remediation. Association of Ground Water Scientists and Engineers Annual Meeting on Innovative Ground Water Technologies for the ’90s, National Ground Water Association, Westerville, Ohio, USA. Ground Water 29 (5)].
