Current state and future development of blue water availability and blue water demand: A view at seven case studies

The current and future situation of blue water availability, blue water withdrawals and the occurrence of water stress is investigated in seven case studies distributed over Africa, Europe and Central Asia, thus representing very different physiographic, climatic and socio-economic conditions. Four scenarios from two major projects dealing with global change are applied to a large scale water model which simulates the case-specific hydrological conditions and water uses. For the assessment of water stress, the ratio between simulated blue water withdrawals and blue water availability is determined. The results of this study clearly demonstrate that climate as well as socio-economic change will have a large impact on the future availability and use of water resources, and consequently on the occurrence of water stress. It is however evident that there are large regional differences of the current and future water stress levels. The application of a number of contrasting scenarios leads to a wide range of possible water futures in some of the investigated regions, thus introducing high uncertainties. Therefore, possible activities towards an implementation of integrated water resources management have to deal with these uncertainties.