Producing reliable hydrologic scenarios from raw climate model outputswithout resorting to meteorological observations

A simplified hydroclimatic modelling workflow is proposedto quantify the impact of climate change on water discharge withoutresorting to meteorological observations. This alternative approach isdesigned by combining asynchronous hydroclimatic modelling and quantileperturbation applied to streamflow observations. Calibration is run byforcing hydrologic models with raw climate model outputs using an objectivefunction that excludes the day-to-day temporal correlation between simulated and observed hydrographs. The resulting hydrologic scenarios provide usefuland reliable information considering that they (1) preserve trends and physical consistency between simulated climate variables, (2) are implemented from amodelling cascade despite observation scarcity, and (3) support theparticipation of end-users in producing and interpreting climate changeimpacts on water resources. The proposed modelling workflow is implementedover four sub-catchments of the Chaudiere River, Canada, using nine North American Coordinated Regional Climate Downscaling Experiment (NA-CORDEX) simulations and a pool of lumped conceptual hydrologicmodels. Results confirm that the proposed workflow produces equivalentprojections of the seasonal mean flows in comparison to a conventionalhydroclimatic modelling approach. They also highlight the sensibility of theproposed workflow to strong biases affecting raw climate model outputs,frequently causing outlying projections of the hydrologic regime.Inappropriate forcing climate simulations were however successfullyidentified (and excluded) using the performance of the simulated hydrologicresponse as a ranking criterion. Results finally suggest that further works should be conducted to confirm the reliability of the proposed workflow toassess the impact of climate change on high- and low-flow events.