ANALYSIS OF THREE-DIMENSIONAL DYNAMICS IN THE ST. LAWRENCE FLUVIAL ESTUARY

This study presents a numerical investigation of the three-dimensional flow dynamics in the St. Lawrence Fluvial Estuary (SLFE), focusing on hydrodynamics interactions at a tidal junction. The research is based on the 3D numerical model, TELEMAC, to capture the complex tidal flow dynamic in this very important freshwater resource. The model is validated with high-resolution field and numerical data, ensuring its reliability for simulating seasonal variations in circulation patterns. It solves the Navier-Stokes equations to accurately represent turbulent flows. The study investigates the impact of vertical velocity components and hysteresis effects on flow dynamics and difference in behavior between channels, emphasizing the importance of advanced modeling techniques in understanding estuarine systems with complex geometry. Results reveal significant spatio-temporal variations in flow patterns and highlight the relevance of 3D modeling during periods of tidal reversal, particularly the presence of opposing currents, vortices and shear stress between vertical layers. These findings provide insight for future research on particle transport (micro/nanoplastics, sediment), pollution, and impacts of climate change.