I am calibrating hydrological models in order to investigate climate change impacts on flow exceedance. I am getting good NSE/KGE scores of 0.9+ for calibrating my various models on observed data. I have 4/5 regional climate models that have future scenario meteorology and historical period meteorology. When analysing the historical datasets with the observed flow for the same time period, the NSE/KGE score is around 0.4/0.5. In order to achieve bias corrected results i assume you run the future scenarios with the optimised parameters from the historical data sets? even though the optimisation scores are lower?