Rondeau‐Genesse et al. (2025) Storyline analytical framework for understanding future severe low-water episodes and their consequences

Identification

• Journal: Hydrology and earth system sciences
• Year: 2025
• Date: 2025-10-01
• Authors: Gabriel Rondeau‐Genesse, Louis‐Philippe Caron, Kristelle Audet, Laurent Da Silva, Daniel Tarte, Rachel Parent, Élise Comeau, Dominic Matte
• DOI: 10.5194/hess-29-4893-2025

Research Groups

• Ouranos inc., Montréal (QC), Canada
• Groupe AGÉCO, Montréal (QC), Canada
• Nada Conseils, Montréal (QC), Canada
• T² Environnement, McMasterville (QC), Canada
• Université du Québec à Montréal (UQÀM), Department of Earth and Atmospheric Sciences, Montréal (QC), Canada

Short Summary

This study develops a storyline analytical framework to project the impacts of future severe low-water episodes in Quebec, based on the 2021 drought, under +2 °C and +3 °C global warming scenarios, revealing significant deterioration in river conditions and extended low-water durations.

Objective

• To apply a storyline approach to generate plausible, physically coherent projections of the 2021 Quebec drought under future climate conditions (+2 °C and +3 °C global warming), incorporating a distributed hydrological model to simulate associated hydrological conditions at provincial and local scales.

Study Configuration

• Spatial Scale: Southern Quebec, encompassing the St. Lawrence River valley and Lake Saint-Jean area, focusing on 9665 river segments with watersheds larger than 50 km².
• Temporal Scale: Historical reference event: 2021 drought. Climatological reference period for indicators: 1992–2021. Future scenarios correspond to global surface temperature increases of +2 °C and +3 °C relative to preindustrial levels (1850–1900), identified using a 30-year centered moving window within simulations spanning 1950–2100.

Methodology and Data

• Models used:
  • Canadian Regional Climate Model (CRCM5) at 0.11° horizontal resolution.
  • Canadian Earth System Model (CanESM2-LE) as the driving model for CRCM5.
  • HYDROTEL physically based, semi-distributed hydrological model.
• Data sources:
  • ERA5-Land reanalysis (9 km spatial grid mesh) for historical precipitation and temperature.
  • Hydroclimatological Atlas of Southern Quebec (1970–present) for historical streamflow data.
  • ClimEx Large Ensemble (50 perturbed simulations from CRCM5 driven by CanESM2-LE) for simulated meteorological data (1950–2100, RCP8.5 emissions scenario).
  • NRCANmet dataset (10 km grid) for bias adjustment of CRCM5 data.
  • Stakeholder consultations (questionnaires and interviews) for documented impacts of past droughts.
  • Standardized Precipitation Evapotranspiration Index (SPEI) for meteorological drought assessment.
  • Hydrological indicators including 14Qmax, Q̄JJA|SON, 7Qmin, LWS start|end, LWS duration, n days<7Q2, and n days<7Q10.

Main Results

• The 2021 drought caused unprecedented hydrological stress in southern Quebec, with streamflow reductions of up to 85% and an extended low-water season (over 2 months longer than usual in affected areas).
• Under a +2 °C warming scenario, summer streamflow could experience an additional reduction of up to 33% compared to 2021, and the number of days below the environmental flow threshold (7Q2) could increase by 15 to 30 days.
• Under a +3 °C warming scenario, low-water conditions are projected to worsen significantly: the low-water season could begin 2–4 weeks earlier and conclude up to a month later, extending its duration by 15 to 45 days compared to 2021. Average seasonal streamflow could further reduce by 33%–67% compared to 2021 levels, and the number of days below 7Q2 could increase by up to 60 days (potentially reaching 100–150 days total in some rivers). The more severe 7Q10 threshold could be exceeded for 25 to 60 days across most rivers.
• These future scenarios imply unprecedented impacts on ecosystems (e.g., biodiversity loss, water quality degradation, altered spawning grounds) and human activities (e.g., municipal water supply stress, increased treatment costs, agricultural yield reductions, recreational tourism limitations).

Contributions

• Introduces and applies a storyline analytical framework to project plausible future extreme drought impacts in Quebec, effectively linking climate change projections to a recent, familiar historical event (the 2021 drought) to enhance stakeholder understanding and decision-making.
• Integrates a distributed hydrological model (HYDROTEL) to simulate detailed hydrological conditions (e.g., streamflow, low-water season characteristics) under future climate scenarios, a novel aspect distinguishing this research from many existing storyline studies.
• Provides physically coherent low-flow indicators at both provincial and local scales, which are particularly valuable for regions like Quebec where formal impact-inducing thresholds for water scarcity are not well understood or defined.
• Emphasizes the critical need for improved systematic data collection on the impacts of meteorological and hydrological droughts on human activities and ecosystems, as well as enhanced research and monitoring of groundwater resources in Quebec, to inform effective climate change adaptation strategies.

Funding

• Gouvernement du Québec
• Québec Ministère du Développement Durable, de l'Environnement et de la Lutte Contre les Changements Climatiques (Plan pour une Économie Verte (PEV))
• Fonds vert (as part of the implementation of the Quebec government's Plan d'action 2013–2020 sur les changements climatiques and the Plan pour une économie verte 2030)
• ClimEx project (Bavarian State Ministry for the Environment and Consumer Protection)
• Gauss Centre for Supercomputing (GCS) for the operation of the SuperMUC supercomputer

Citation

@article{RondeauGenesse2025Storyline,
  author = {Rondeau‐Genesse, Gabriel and Caron, Louis‐Philippe and Audet, Kristelle and Silva, Laurent Da and Tarte, Daniel and Parent, Rachel and Comeau, Élise and Matte, Dominic},
  title = {Storyline analytical framework for understanding future severe low-water episodes and their consequences},
  journal = {Hydrology and earth system sciences},
  year = {2025},
  doi = {10.5194/hess-29-4893-2025},
  url = {https://doi.org/10.5194/hess-29-4893-2025}
}