The regional climate model as a tool for long-term planning of Quebec water resources

'Full text': In recent years, important progress has been made in downscaling GCM (Global Climate Model) projections to a resolution where hydrological studies become feasible. Climate change simulations performed with RCMs (Regional Climate Models) have reached a level of confidence that allows us to take advantage of this information in long-term planning of water resources. The RCMs' main advantage consist in their construction based on balanced land as well as atmosphere water and energy budgets, and on their inclusion of feedbacks between the surface and the atmosphere. Such models therefore generate sequences of weather events, providing long time series of hydro-climatic variables that are internally consistent, allowing the analysis of hydrologic regimes. At OURANOS, special attention is placed on the hydrological cycle, given its key role on socioeconomic activities. The Canadian Regional Climate Model (CRCM) was developed as a potential tool to provide climate projections at the watershed scale. Various analyses performed over small basins in Quebec provide information on the level of confidence we have in the CRCM for use in hydrological studies. Even though this approach is not free of uncertainty, it was found useful by some water resource managers and hence this information should be considered. One of the keys to retain usefulness, despite the associated uncertainties, is to make use of more than a single regional climate projection. This approach will allow for the evaluation of the climate change signal and its associated level of confidence. Such a methodology is already applied by Hydro-Quebec in the long-term planning of its water resources for hydroelectric generation over the Quebec territory. (author)