ABSTRACT
Recently, integrated approaches for describing, modelling, and forecasting physical, social, economic, and political processes related to the hydrological cycle, in particular with regards to Global Change, have gained worldwide attention both with administrative authorities and in the research community. Water affects all economic, cultural, social and ecological aspects of daily life. It is the basis of functioning matter cycles and hence of a clean, stable and sustainable environment. A functional understanding of the processes related to the water cycle and the influence of human societies upon these is crucial for the development of ways for
the sustainable management of water. Since the related processes are strongly inter-related, sectoral science approaches are neither capable of understanding the complex interactions between nature, water and man nor of developing methods for a sustainable water resource management under globally changing boundary conditions. A high level of trans-disciplinary integration is required to provide a profound scientific knowledge base, taking into account continuously changing natural, social and technological boundary conditions known as Global Environmental Change. Proactive watershed management aiming at a sustainable use of the water resources thus relies heavily on the development of future scenarios and on numerical models with predictive abilities. To date, no commonly accepted modelling approaches are available to integratively describe the complex interactions between natural and social processes. The lack of successful integration concepts is the result of large differences in the way the various disciplines formalize and describe their understanding of the respective processes. These differences in terms and concepts, comprehension and methodology lead to sectoral approaches for solving separate parts of the task, and hence provide no reliable basis for simulating recursive and interactive scenarios of future development.
