On the Impacts of Ice Cover on Flow Profiles in a Bend

We investigate the impact of ice coverage on flow and bed shear stress profiles in a river bend. We perform field measurements using Acoustic Doppler Current Profiler in a bend of the Red River, North Dakota, the United States. Field campaigns were carried out under both open-surface and ice-covered conditions in 2020 and 2021. Our results show that the time-averaged velocity profile follows closely the quartic solution (Guo et al., 2017, under full ice coverage. While the flow profile under open-surface condition follows closely the logarithmic law near the bed, it is challenging to identify the logarithmic layers in our measured data under ice-covered condition. Our results also show that the impact of ice coverage is most significant near both banks where the vertical velocity profile is modified significantly due to the interaction of turbulent flows with the ice cover. Our results suggest that the bend curvature and ice coverage both have significant impacts on the velocity profile as well as the distribution of the bed shear stresses. Our findings provide new insights on sediment transport processes of ice-covered rivers, especially during the break-up period when the surface coverage changes rapidly.