Storyline Analytical Framework for Understanding Future Severe Low-Water Episodes and Their Consequences

Abstract. The 2021 drought highlighted the vulnerability of Quebec's water resources and the potential for widespread consequences in a region that is generally perceived as having abundant water. This study uses a storyline approach to explore the plausible impacts of future drought conditions for an event similar to what occurred in 2021, but under two different warming scenarios corresponding to increases of 2 °C and 3 °C in global surface temperatures compared to preindustrial levels. The approach employs analogues derived from a large ensemble of regional climate simulations combined with simulations generated by a hydrological model to offer a comprehensive understanding of both climate and hydrological conditions during, and leading up to, these potential future events. This approach allowed for enhanced collaboration with water management experts and other stakeholders to project the possible impacts of climate change on serious water deficits in Quebec. Results indicate a further deterioration in river conditions, particularly under a +3 °C global temperature rise. In the hardest-hit areas of the province under that scenario, future low-water levels persist for a month longer and river streamflows drop by an additional 50 %, thus falling short of the threshold required to maintain the health of ecosystems for an extended period of time and suggesting significant impacts on ecosystems and human activities. This study also highlights the need for improved systematic data collection during meteorological and hydrological droughts in Quebec, particularly with respect to their impacts on human activities and ecosystems.