Flood risk and dike safety with respect to climate change, are of concern to the Vidaa river system in Denmark. In order to understand the expected impacts of climate change on the river, we conducted extensive hydrological and hydraulic studies. As a result of our comprehensive analyses and projections, informed decisions on climate adaptation can now be taken with confidence.
The Vidaa River system, located in the southern part of Jutland, Denmark and northern Germany discharges into the Wadden Sea through a tidal sluice. During storm surges, when the sluice gate is closed for an extended period of time, extreme water level conditions occur in the river system. This can be further amplified by increased runoff from the catchment owing to heavy precipitation. With climate change, rising sea levels, more severe storm surges, and heavier extreme rainfall events are expected in the future. In light of these future scenarios, it has become necessary to evaluate the changes in flood risks and dike safety.
We set up and calibrated a MIKE 11 integrated hydrological and hydraulic model of the Vidaa River catchment.
We used Regional Climate Model (RCM) projections from the ENSEMBLES data archive for two projection horizons. We also used the Extreme Value Analysis (EVA) software package – part of our MIKE by DHI software suite – for the risk analysis studies.
The project showed how much flood risk is expected to increase in the future due to climate change. The results obtained in the study are currently used for evaluating different adaptation options for reducing future flood risks in the long-term planning of the area.