A comprehensive fluvial geomorphology study of riverbank erosion on the Red River in Winnipeg, Manitoba, Canada

•Seasonal freeze-thaw significantly impacted the Red River bank material.•Riverbank erodibility was estimated by a coupled thermal and hydrodynamic model.•The first freeze-thaw cycle significantly reduced critical shear stresses.•Simple method was developed to estimate applied shear stresses on the Red River.

SummaryRiverbank erosion on the Red River in Winnipeg, Manitoba has raised concerns over the last 20 years and more. Although several recent studies have shown that fluvial erosion can reduce riverbank stability and promote geotechnical slope failure, there are too few that have focused on this phenomenon. The present study includes field measurements, experimental testing, and numerical modelling to quantify fluvial erosion through a 10 km reach of the Red River. Results have shown that seasonal freeze-thaw processes can dramatically reduce the critical shear stress and increase erodibility of the riverbanks. Moreover, a simple method has been employed using hydrodynamic numerical models to define the applied shear stresses on the river banks based on the river water level, which will be useful for further research and design purposes. The TEMP/W numerical model was used to define seasonal frost depth to estimate freeze-thaw effects. Finally all field measurements, experimental and numerical models results were used to predict annual fluvial erosion through this reach of the river.