The Impacts of Water Level Fluctuations on the Ecosystem and Uses of the St. Lawrence

Introduction

As part of the work of the Water Level Subcommittee of the Biodiversity component, Environment Canada and Environment Quebec researchers are developing a model to describe the dynamics and ecosystem behaviour of the freshwater section of the St. Lawrence River.

The program focuses on the quantitative analysis of the impacts of flow and water level variations on the physical, chemical, biological and socio-economic characteristics of the St. Lawrence River ecosystem. Changes in current speed, hydraulic retention and flooded areas will be evaluated using a hydrodynamic model in which shoreline erosion and the transportation of contaminants could one day be incorporated. The biological impacts include changes to wetlands (area, productivity and diversity) and the recruitment and growth of fish and waterfowl. Water level variations can also potentially affect exotic species and parasites, as well as a large number of recreational activities taking place along the banks of the river.

This work will provide us with a better understanding of the effects of such water-level fluctuations and thus help us improve management methods.

Modelling the St. Lawrence freshwater ecosystem

Modelling the freshwater ecosystem involves describing the high-resolution topography of the riverbed and the spatial distribution of substrate types and aquatic plants, which have a major impact on the physical environment. This river modelling work makes use of current computer and Geographic Information System (GIS) technology, as well as mathematical models and extensive field data. As a result, the value of physical variables can be predicted for the entire river with satisfactory accuracy, under all possible conditions, including those that have never been observed.

Digital tools will be used for two-dimensional simulations of various water level, current, wave and light conditions. Based on the results obtained, variables such as sediment dynamics, water mass distribution and residence time, and water temperature can be simulated.

For more information, see Le Fleuve Newsletter, volume 11, issue 4.

Contacts:

Jean-François Cantin
Canadian Meteorological Centre
Telephone: (418) 649-6565
Email: jean-francois.cantin@ec.gc.ca

Christiane Hudon
Centre Saint-Laurent
Téléphone : (514) 283-5195
Courriel : christiane.hudon@ec.gc.ca

Marc Mingelbier
Société de la faune et des parcs du Québec
Telephone: (418) 521-3955, ext. 4486
Email: marc.mingelbier@fapaq.gouv.qc.ca

Jean Morin
Canadian Meteorological Centre
Telephone: (418) 649-6017
Email: jean.morin@ec.gc.ca