A Large International River: The Danube. Summary of Hydrological Conditions and Water Management Problems in the Danube Basin

The demand of policy makers and managers to find environmentally sound and sustainable economic development is obvious. At the same time, various branches of sciences dealing with environmental issues have become more and more specialized. The solution to problems -- often of a global character -- requires the interdisciplinary analysis of versatile systems consisting of natural, economic and social elements of the environment. Within the long series of water related topics of IIASA's Environment Program, a new project "Decision Support Systems for Managing Large International Rivers" (LIR) was recently launched. The formulation of environmentally sound management policy for land-use and water resources development requires the reliable prediction of the impacts of different human interventions in order to eliminate conflicts between different interest groups, and to preserve the quality of life in both the biosphere and society. Several models for the assessment of various environmental impacts already exist, but the large scale of river basins and the amount of data -- the availability of which is even limited in some cases -- require the development of aggregated systems of models that can provide decision makers with easily understandable information at various hierarchical levels. Considering this requirement, the objective of the project is to construct a computer-based interactive data and information system to facilitate the effective participation of policy making authorities in determining current conditions and expected changes in hydrological systems. The outline of LIR emphasizes the importance of the preparation of case studies. Their role is not only to check the applicability on the system for solving actually occurring problems, but the analysis of the basins as cases will assist in selecting the crucial questions that should be answered by the Decision Support System. The Danube basin was chosen as the first case study to be investigated in the framework of LIR. The reason for this choice is partly that IIASA is located in the basin, and, thus all information easily accessible. The international character of the river (there are 8 riparian countries and 3 others sharing a small part of the catchment), the rapidly developing problems of the utilization of water (canalization, increasing transboundary pollution, seasonal water shortage), and the efforts of the riparian countries to improve the conditions of water resources development within the basin (which is clearly indicated by the fact that a joint declaration was signed) are also reasons supporting the selection of the Danube as the first case study. Naturally, the hydrological conditions of the river system and the water management problems occurring within the catchment are well known for the experts in water sciences working in the riparian countries. For experts participating in the project and coming from other countries, or, representing other scientific disciplines, it is necessary, however, to summarize the most important information describing the water regime of the river system and the obstacles hindering the development of water resources in the basin. This working paper and the detailed list of references provide more information on water management in the Danube basin