Hindcast of Water Level and Flow in the St. Lawrence River Over the 2005–2012 Period

ABSTRACT

A one-dimensional model was run to hindcast water levels and flows for the St. Lawrence River between Montréal and Saint-Joseph-de-la-Rive (100 km east of Québec, Canada). At the upstream boundary, the model uses the flows from Lake Ontario and the Ottawa River basin through lakes Saint-Louis and des Deux-Montagnes and from tributary rivers inside the domain, while at the downstream boundary, it uses water level observations and wind forcing, over the 2005–2012 period. Observations of water level in real time are available at 18 water level gauges but model results provide values at 1061 positions within the domain. The water flow is not measured in real time. Calibration of the model flows provides the ability to issue the flow at the same positions and at the same 3-minute frequency as the water level. Daily flow hindcasts of the St. Lawrence River at Québec over the period is presented. The uncertainties associated with the model results are evaluated using water level and flow observations.

RÉSUMÉ

Un modèle unidimensionnel est utilisé pour reproduire les niveaux d’eau et les débits du fleuve Saint-Laurent entre Montréal et Saint-Joseph-de-la-Rive (100 km à l'est de Québec, Canada). Le modèle utilise comme frontière amont les débits du lac Ontario et du bassin de la rivière des Outaouais par les lacs Saint-Louis et des Deux-Montagnes et des tributaires au sein du domaine, tandis qu’à la frontière aval ce sont les observations de niveau d'eau et l’influence du vent, pour la période 2005–2012. Les niveaux d'eau sont disponibles en temps réel à 18 stations, mais les résultats du modèle fournissent des valeurs à 1061 positions au sein du domaine. Le débit n’est pas mesuré en temps réel. L'étalonnage des débits du modèle permet de pouvoir les obtenir aux mêmes positions et à la même fréquence de 3 minutes que les niveaux d'eau. La reproduction du débit quotidien du fleuve Saint-Laurent à Québec pour la période est donnée. Les incertitudes associées aux résultats du modèle sont évaluées en utilisant les observations de niveau d'eau et de débit.

KEYWORDS:

• estuary
• stage-discharge
• water level
• flow
• hindcast
• St. Lawrence River

Acknowledgements

The two first authors were affiliated with the Canadian Hydrographic Service (CHS), Québec Region, when this study was initiated. We would like to acknowledge the support of the management team, in particular of former director Dr. Andrée Bolduc, for her steadfast support throughout this endeavour. Many other members of CHS made important contributions for which we are grateful: Annie Biron implemented the bathymetric sections in the model from the surveys; Frédéric Lavoie computed volumes from bathymetry over sections of the model; André Godin performed tidal analysis on water level data. The St. Lawrence Global Observatory management team gave us strong support, and Johanne Noël produced Figs 1, 2, and 3. Jean-François Cantin (Hydrologic and Ecohydraulics Division, Meteorological Service of Canada, Environment Canada) provided the stage-discharge relationships at the outflow of lakes des Deux-Montagnes and Saint-Louis as well as the water level data. We also wish to thank two anonymous reviewers for their constructive comments on a previous version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.