Michael Kaltofen

Trends in water demand and water availability for power plants—scenario analyses for the German capital Berlin

The availability of electric power is an important prerequisite for the development or maintenance of high living standards. Global change, including socio-economic change and climate change, is a challenge for those who have to deal with the long-term management of thermoelectric power plants. Power plants have lifetimes of several decades. Their water demand changes with climate parameters in the short and medium term. In the long term, the water demand will change as old units are retired and new generating units are built. The present paper analyses the effects of global change and options for adapting to water shortages for power plants in the German capital Berlin in the short and long term. The interconnection between power plants, i.e. water demand, and water resources management, i.e. water availability, is described. Using different models, scenarios of socio-economic and climate change are analysed. One finding is that by changing the cooling system of power plants from a once-through system to a closed-circuit cooling system the vulnerability of power plants can be reduced considerably. Such modified cooling systems also are much more robust with respect to the effects of climate change and declining streamflows due to human activities in the basin under study. Notwithstanding the possible adaptations analysed for power plants in Berlin, increased economic costs are expected due to declining streamflows and higher water temperatures.

Adaptation strategies to global change for water resources management in the Spree river Catchment, Germany

Abstract Computer models for long‐term simulations of water resources management strategies are used in the analysis of water availability problems in river basins. Such models can also be used for the examination of global change impacts, which are characterised by changed natural water yield and water demand due to climate and socio‐economic changes. Already existing water quantity and water quality problems in the catchments of the river Spree and the river Schwarze Elster were analysed in the context of global change. The main water quantity issues are caused by the future development of the mining industry and climate change. The effects of these future developments were analysed using the long‐term water resources management model WBalMo. Subsequently, adaptation strategies were defined in co‐operation with the relevant stakeholders and their effects analysed with the same model. The results show that continuation of the existing water resources management strategy will not be able to compensate for the impacts of global change. However, a changed management strategy might compensate the impacts for some users.

Integration of Economic Evaluation into Water Management Simulation

In this chapter it is shown how economic evaluation algorithms of water use can be integrated into a long-term water management model such that surface-water availability and economic evaluation of various levels of water availability to different uses can be modeled simultaneously. This approach makes it possible to include essential features of economic analyses of water use into water resource modeling and thus improves the capability of such models to support decision making in water management. This is especially relevant for the implementation of the Water Framework Directive, which requires economic analyses to be included in the decision process about future water management strategies. The water management simulation model WBalMo is presented and the integration of economic-evaluation algorithms is demonstrated for the examples of surface-water use for fish farming and for filling open-cast mining pits in order to achieve acceptable water-quality levels in the emerging pit lakes. Results of applying this integrated evaluation approach are shown for different water management scenarios under conditions of global change in the East German Spree and Schwarze Elster river basins, where water scarcity is an urgent issue. Among the lessons which are drawn by the authors one lesson reads that integrating economic evaluation algorithms into a pre-existing model might bring enormous problems. Therefore, such model approaches should be developed together by water engineers and economists in an interdisciplinary endeavor right from the start.

Potential impacts of climate change on natural and managed discharges of the Rivers Spree, Schwarze Elster and Lusatian Neisse, Central Europe

The water balance of the Rivers Spree, Schwarze Elster and Lusatian Neisse is profoundly disturbed due to large-scale open-cast lignite mining activities and water management. Together with continental climate conditions this affects water resources and water users in the region. Driven by scenarios of the regional climate model STAR which assume increasing temperature and decreasing precipitation, two hydrological models, the Soil and Water Integrated Model SWIM and the catchment model EGMO simulate declining natural discharges in the region. Thus, decreasing managed discharges are simulated with the long term water management model WBalMo. The refinement of the simulation time step of WBalMo from months to weeks improves the consideration of climate variability and is also associated with higher simulated managed discharges in early summer. Management scenarios in terms of a reduced outlet capacity of a mining lake reservoir result in higher releases from other reservoirs and slightly reduced summer discharges in downstream river sections.