Integration of Hydrological Climate Change Impact Modelling Into Optimization of New Reservoirs

Projected climate change impacts on water resource systems show a high urgency for adaption measures. Especially for large scale constructions with long planning and construction phases a design that is based solely on observed discharge time series can lead to over- or underdesign. In order to include climate change effects into the planning process, often a multiplier based on hydrological impact studies is used. In the case of multi-functional and interconnected reservoirs, this approach is not suitable due to partially conflicting operation goals. In this ongoing study, we present a methodology that combines state of the art hydrological modelling of climate change impacts with the planning of new reservoirs and constructional updates of existing reservoirs. For this purpose, a model chain is used that includes an ensemble of bias-corrected regional climate models (RCMs), a semi-distributed hydrological catchment model, a numerical reservoir operation model and 2D hydrodynamic models. The model chain is applied to the region of the Western Harz mountain range (Lower Saxony, Germany) and its directly affected downstream area. Here, in total six partially interconnected reservoirs serve the system services flood protection, drinking water supply, energy generation and low water augmentation. Supplementary constructional variants to support the reliability of the existing system in a changing climate are analysed by implementing them in the described models. Intermediate results for the mitigation of projected flood risk changes indicate that the presented constructional variant could more than compensate the projected climate change impact on flood risk from the upper catchment.