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

Abstract

Ice coverage has been recognized as an important hydraulic aspect of alluvial channels for a long time (Guo et al., 2017). The role of river ice in ecological (Prowse, 2001b), morphological (Ettema, 2002, and hydraulic aspects (Prowse, 2001a) have been well recognized. Recent evidence suggests that it plays an important role in regulating large-scale turbulent structures (Biron et al., 2019) and ultimately channel lateral migration (Turcotte et al., 2011). Under the impact of climate change, the loss of river ice (Yang et al., 2020) is expected to lead to detrimental consequences for aquatic environments (Thellman et al., 2021). Despite its importance, our understanding of icy flows is rather limited because of challenges related to field measurements. The goal of this study is to examine the impacts of ice coverage on flow profiles in a meandering bend, a common feature of the riverine system.Field measurement of turbulent flows in rivers is challenging even under open-surface condition (Petrie et al., 2013), especially when secondary flow is observed (Moradi et al., 2019). The measurement under ice coverage poses a different set of safety and accuracy issues when instruments are placed beneath the ice layer (Biron et al., 2019). Under a fully frozen surface, it is necessary to drill holes across the ice layer in order to make the sensor submerged. In particular, it is challenging to obtain reliable data close to the ice layer as well as the river bed (Attar & Li, 2013).As the top surface is frozen during winter (Ettema, 2002), it provides an additional layer of roughness in addition to the river bed. The presence of the ice coverage alters the spatial distribution of the entire velocity profile. Ice coverage creates a significant difference between the physical characteristics of surface and bed, forming an asymmetrical flow configuration (Chen et al., 2018;Parthasarathy & Muste, 1994). The asymmetrical flow

Transverse flow distributions in ice‐covered channels

“…Additionally, it provides information on the river thermal‐ice processes, such as the evolution of undercover transport of frazil granules that contribute to the development of hanging dams (Shen & Wang, 1995) and the development of border ice (Huang et al, 2012). The existence of ice cover provides thermal insulation and additional surface resistance for river flow, and thus significantly changing the boundary shear stress distribution, velocity profiles, and turbulence characteristics (Easa, 2017; Koyuncu & Le, 2022; Tatinclaux & Gogus, 1983). Teal et al (1994) systematically compared 10 point‐velocity measurement techniques with field velocity profiles under the ice cover.…”