Modélisation hydrodynamique du lac Saint-Pierre, fleuve Saint-Laurent : l'influence de la végétation aquatique

Abstract

The macrophytes (aquatic plants) can have a substantial effect on the hydrodynamics of some watercourses. A mathematical formulation for the resistance effect of macrophytes on the current is inserted in a two-dimensional finite element hydrodynamic model. The method introduced herein allows to take into account the morphology, the density, and the growth curve of the different species of macrophytes present in the river. The Lake Saint-Pierre between Sorel and Trois-Rivières (Québec, Canada) in the St. Lawrence River is used to demonstrate the approach. The mathematical aspect of the model is first briefly presented. The field surveys of macrophytes and some other data sets used with the model are then analyzed. Finally, after the calibration–validation step, which insures the good behavior of the model, some results are presented to show the effect of the macrophytes on the flow structure. Key words: hydrodynamics, aquatic plants, St. Lawrence River, Lake Saint-Pierre, two-dimensional modelling, simulation, finite element method, Manning's coefficient.