A global portrait of hydrological changes at the 2050 horizon for the province of Québec

This paper presents the methodology and results of a vast study on climate change impacts on hydrology for the province of Qubec for the 2050 horizon.A climate ensemble was first built with simulations from the World Climate Research Programme (WCRP)'s Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset, the North American Regional Climate Change Assessment Program (NARCCAP) and the Canadian Regional Climate Model (CRCM) operational runs.Direct outputs and post-processed data from the climate simulations were used as input to the calibrated HSAMI hydrological model in order to produce a large ensemble of hydrological projections for 305 Qubec watersheds.Simulations results indicate that increases in mean annual streamflow are projected for the whole province, with greater changes (up to 14%) in the north.The intra-annual distribution of streamflow also changes, with higher winter flows and lower summer flows as well as apparently earlier spring floods.The maximum height of the snow cover and the number of days with snow on the ground are likely to diminish for the 2050 horizon for the southern half of the province, while the northern half will see more snow, but a shorter snow season as well.Cet article prsente la mthodologie et les rsultats d'une vaste tude portant sur l'impact des changements climatiques sur l'hydrologie au Qubec l'horizon 2050.Un ensemble climatique a d'abord t construit partir de simulations provenant de la base de donnes multi-modles de la troisime phase du World Climate Research Programme's Coupled Model Intercomparison Project (CMIP3), du North American Regional Climate Change Assessment Program (NARC-CAP) et de simulations oprationnelles du Modle Rgional Canadien du Climat (MRCC).Les sorties directes ainsi que post-traites de ces simulations climatiques ont servi alimenter le modle hydrologique HSAMI calibr afin de produire un large ensemble de projections hydrologiques pour 305 bassins versants du Qubec.Les rsultats des simulations indiquent que des augmentations du dbit annuel moyen sont projetes pour l'ensemble du Qubec, avec des changements plus importants (jusqu' 14%) dans le nord.La distribution intra-annuelle du dbit change galement, avec des dbits hivernaux plus soutenus et des dbits estivaux diminus, ainsi que des crues printanires devances.L'accumulation maximale de neige et le nombre de jours avec de la neige au sol diminueront probablement l'horizon 2050 pour la moiti sud de la province, alors que la moiti nord verra plus de neige, mais une saison plus courte tel qu'au sud.