Hydrological model calibration in high streamflow extremes climate change studies

Studies on the effects of climate change on hydrological extremes frequently use hydrological models whose parameters are determined through calibration techniques utilizing observed meteorological data as input force. However, when climate models are applied, this procedure result in a biased evaluation of the probability distribution of high streamflow extremes. As an alternative, we present a methodology called "Hydrological Calibration of eXtremes" (HyCoX), which involves maximizing the likelihood that the predicted and observed high streamflow extremes belong to the same statistical population by means of hydrological model calibrations driven by climate model output.

The application of HYPERstreamHS, a distributed hydrological model, to the Adige River watershed (southeastern Alps, Italy), shows that this technique retains statistical coherence and produce accurate quantiles of the yearly maximum streamflow.