Glacial melt and potential impacts on water resources in the Canadian Rocky Mountains

• Published in: Water Resources Research
• Main Authors: Castellazzi, Pascal, Burgess, D., Rivera, Alfonso, Huang, J., Longuevergne, Laurent, Demuth, Michael
• Other Authors: Geological Survey of Canada Québec (GSC Québec), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Canadian Geodetic Survey, Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; Arctic; Arctic Ocean; Hudson; Hudson Bay; Pacific; Climate change
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-02369819; https://hal-insu.archives-ouvertes.fr/insu-02369819/document; https://hal-insu.archives-ouvertes.fr/insu-02369819/file/Castellazzi_et_al-2019-Water_Resources_Research.pdf; https://doi.org/10.1029/2018WR024295

International audience As a result of global climate change, glacial melt occurs worldwide. Major impacts are expected on the dynamics of aquifers and rivers in and downstream of mountain ranges. This study aims at quantifying the melt water input fluxes into the watersheds draining the Canadian Rocky Mountains and improving our knowledge about the fate of meltwater within the hydrological cycle. To this end, we use (1) time‐variable gravity data from GRACE satellites that is decomposed into water storage change; (2) an ensemble of glacier information: in situ observations, geodetic measurements, and a mass balance model and (3) in situ surface water and groundwater level observations. The glacier mass balance model estimates a total ice mass change of ~43 Gt for the period 2002‐2015, corresponding to an average of ‐3,056 (±2,275) MCM/yr. 78% of the meltwater total flows West of the continental divide (to the Pacific Ocean), while 22% flows East of the continental divide (to the Arctic Ocean and Hudson Bay). However, the GRACE‐derived total water storage increases, suggesting that groundwater storage compensates for the glacial melt with an increase of 3,976 (± 2,819) MCM/yr. A plausible explanation is that meltwater is not immediately flowing down in rivers but rather stored locally in aquifers. This hypothesis is supported by in situ river base flow observations, showing base flow increase in basins draining the ice melt, mostly west of the continental divide. Direct in situ evidences such as well water level time‐series are not sufficiently available to fully support this hypothesis.