The management of water resources is closely linked to water availability, economic development, social wealth and the environment. These interactions complicate the evaluation of water resources management activities. By taking these interactions into account, it is possible to take a step towards a sustainable water resources management. Uncertainties, e.g. regarding the socio-economic development or water availability, especially under climate change conditions, have to be included in the evaluation. Scenario analysis is one way of dealing with these uncertainties. In this thesis scenarios are assessed in the context of global change, comprising of climate change and socio-economic change.
Based on the water management simulation model WBalMo, a model for the catchments of the rivers Spree and Schwarze Elster (Germany), where lignite mining activities have an important influence on water availability, was developed. Two effects of global change affecting water availability, the phasing out of mining activities until 2040 and the inclusion of a transient climate change scenario with a warming of 1.4 K until 2050, were considered. In order to determine the effects of climate variability and climate change, 100 realisations of stochastic input series with and without climate change were used. To mitigate the effects of climate change, alternative water resources management strategies were developed. In order to estimate the robustness of these alternative strategies they were also simulated under the assumption of a stable climate.
Two socio-economic scenarios, according to the IPCC-storylines A 1 and B 2, were used. Both socio-economic trends are represented in terms of differences in economic values (costs, benefits). Regarding the economic effects of water resources management strategies water utilisations (tourism, fish farming) and costs for the operation of water resources management utilities (water transfers etc.) and for conditioning of mining lakes (neutralisation), were analysed. The economic and ecological evaluation functions are integrated into the water management simulation model. The single economic indicators are summarised to the criteria net benefit. To assess the ecological impacts the indicator ecological required minimum discharge is used and assessed using a scale ranging from zero to one hundred.
Some of the economic indicators are conditional to the cost for the operation of water resources management utilities. Therefore the summation of the single indicators for the criteria net benefit has to be executed separately for each realisation. Thus 100 values for each scenario are the result for the aggregated criteria net benefit. The values for ecologically required minimum discharge are also connected to the operation of water resources management utilities, this indicator also has to be assigned to the corresponding realisation. 100 vectors with two columns, one containing the criteria net benefit, the other containing the ecological criteria, are the result of this summation.
The results obtained from the stochastic input series with and without climate change are independent. Therefore, different procedures to compare the results obtained from the same series and to compare the results obtained from different series are presented. By comparing the results obtained for the water resources management strategies under different socio-economic trends and different climate scenarios the robustness of the water resources management strategies was assessed.