Climate change impacts on hydrology and electricity production – a case study from Drammen river basin in Norway

In this paper, we have assessed how climate change might impact hydrology and electricity production in the Drammen River basin. To assess climate change impacts, downscaled scenarios from several combinations of GCMs, RCMs and bias correction algorithms from both CMIP5 and CMIP6 were used by a gridded hydrologic model (HBV) to simulate runoff for a reference period and a future period. Thereafter the energy market model EOPS has been used to simulate electricity production, reservoir water levels, bypass and flood flows. In Drammen, we see an increase in runoff, a reduction in the average seasonal variation in runoff and an increase in year-to-year variability. Most of the increase can be used for electricity production. There is an increase in flood risk during autumn and early winter and higher drought risk during summer. The increase in the year-to-year variability will impose new challenges for water resources management in the Drammen river basin.