Amélioration de la modélisation des variables hydrologiques et évaluation de l’impact des changements climatiques au Québec

Abstract

This thesis aims to improve the modeling of hydrological variables and assess the impacts of climate change on watersheds in Quebec, with a focus on the application of the WaSiM model and climate projections from CMIP6. The research addresses three key aspects: optimizing the configuration of the hydrological model, comparing conventional and asynchronous modeling methods, and evaluating the impacts of climate change on hydrological variables. In the first part of the study, three calibration configurations of the WaSiM model are compared. The configuration that incorporates recharge into the model’s calibration, while slightly less accurate in reproducing observed streamflow, provides superior precision in simulating internal hydrological processes. This highlights the importance of multi-variable calibration to limit equifinality and improve the representation of hydrological variables. The second part of the study compares the performance of conventional and asynchronous modeling methods. The asynchronous approach, which eliminates the reliance on historical meteorological data, presents potential advantages in regions where observational data are limited or unreliable. However, it shows shortcomings in accurately capturing the timing of hydrological events, particularly snowmelt. This method suffers from inconsistencies in synchronizing seasonal processes, underlining the need for future research to incorporate some form of synchronicity in the asynchronous method to improve the reliability of hydrological projections. The third part evaluates the impacts of climate change across 34 watersheds in southern Quebec. The results indicate an increase in total precipitation and temperature, with a significant shift from snowfall to rainfall, reduced snow accumulation, and earlier spring peak flows. The projections also show an increase in groundwater recharge during winter and spring, while evapotranspiration intensifies during the warmer months. These findings provide critical insights for water resource management in the context of climate change. This thesis emphasizes the importance of multi-variable calibration and the use of the latest climate projections to enhance hydrological modeling.

Date	26 Mar 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Richard Arsenault (Supervisor) & Jean Daniel Sylvain (Co-supervisor)