Impact des lames de glace sur la réponse hydrologique du manteau neigeux à Sainte Marthe, au sud du Québec

Abstract

In a context where northern regions are showing significant signs of vulnerability to climate change, it becomes necessary to study more specifically the behaviour of the snowpack in these regions where snow plays a significant hydrological role. These regions are now affected by increasingly frequent rain-on-snow episodes. These episodes, whose hydrological impact is still unknown, are only exceptionally represented in current hydrological models, which may affect water resource management or the assessment of long-term natural risks. The objective of this research is to better understand how the structure of the snowpack will evolve during the winter of 2018-2019 and the resulting hydrological processes. The specific objectives here are to detect and quantify lateral flows that impact the water balance of the snowpack and to understand the conditions that led to their occurrence in a flat area. For that, the study of snowpack dynamics and its hydrological response is based on hydrometeorological data and manual measurements collected in the Sainte Marthe experimental watershed, located in the southern region of Quebec, Canada. The manual measurements are used to determine the snowpack profile throughout the winter, while the data collected also allow mass and energy balances to be established. Numerous ice layers formed within the snowpack during the winter of 2018 2019. In early winter, weather variability tends to favour the creation of a thick basal ice layer that will persist until the end of the winter. The development of ice layers in mid winter is established after episodes of mild weather often accompanied by rain. Hydrological components measured at the watershed show that these ice layers modify the flows and the evolution of the snowpack. The existence of the ice layers promotes lateral flow within the snowpack until it flows into the streamlet without contact with the ground near the point of infiltration. If as predicted by climate models, winter conditions in southern Quebec should be more favourable to the formation of ice layers in the snowpack resulting in significant changes to the hydrology of the watersheds. It is therefore recommended that processes associated with the presence of ice layers be integrated into hydrological models to allow their consideration for water resource management.

Date	24 Aug 2020
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Michel Baraër (Supervisor)