『Abstract
　Groundwater modeling is undergoing a change from traditional stand-alone studies towards being an integrated part of holistic water resources management procedures. This is illustrated by the development in Denmark, where comprehensive national databases for geologic borehole data, groundwater-related geophysical data, geologic models, as well as national groundwater-surface water model have been established and integrated to support water management. This has enhanced the benefits of using groundwater models. Based on insight gained from this Danish experience, a scientifically realistic scenario for the use of groundwater modeling in 2020 has been developed, in which groundwater models will be a part of sophisticated databases and modeling systems. The databases and numerical models will be seamlessly integrated, and the tasks of monitoring and modeling will be merged. Numerical models for atmospheric, surface water, and groundwater processes will be coupled in one integrated modeling system that can operate at a wide range of spatial scales. Furthermore, the management systems will be constructed with a focus on building credibility of model and data use among all stakeholders and on facilitating a learning process whereby data and models, as well as stakeholders' understanding of the system, are updated to currently available information. The key scientific challenges for achieving this are (1) developing new methodologies for integration of statistical and qualitative uncertainty; (2) mapping geological heterogeneity and developing scaling methodologies; (3) developing coupled model codes; and (4) developing integrated information systems, including quality assurance and uncertainty information that facilitate active stakeholder involvement and learning.』

Introduction
Methodology
Analysis step 1: Long-term trend in groundwater modeling in Denmark
　Situation in mid-1990s (1995 in Table 1)
　Situation today (2009 in Table 1)
　Possible future scenario (2020 in Table 1)
Analysis step 2: Status and research needs
　Geologic and geophysical data - national databases
　　International status
　　Status in Denmark
　　Need for further developments and research challenges
　Conceptual models - National databases
　　International status
　　Status in Denmark
　　Need for further developments and research challenges
　National integrated hydrologic models
　　International status
　　Status in Denmark
　　Need for further developments and research challenges
Analysis step 3: Examples of integrated applications
　Example 1: Geophysical and geologic mapping and interpretations
　Example 2: national hydrologic model
Discussion
　The Danish experience
　Vision for information and decision support system in 2020
　Scientific challenges
　　Characterizing geologic uncertainty and storing the information in databases
　　Characterizing geologic heterogeneity and storing such information in databases
　　Developing integrated modeling systems - Coupling of model codes
　　Developing integrated information systems
Conclusions
Acknowledgments
References