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How a river restoration structure will resist ice action or affect the local ice regime are poorly understood. This paper presents a numerical model study focusing on the performance of rock vanes and cross vanes under ice run conditions. The two-dimensional river ice dynamics model, DynaRICE, was extended to study the effect of ice runs on cross v...
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... simulated results compare well with the experimental observations of Vuyovich et al. (2009). Figures 5 and 6 show the deposition and scour upstream and downstream of the structures. In the without-structures cases, transport was negligible over the ten hours of simulation compared to the with-cross vanes case. ...
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Citations
... Laboratory tests of cross-vane structures (Vuyovich et al. 2009) found them to increase ice accumulation and be at risk for failure due to rock movement. Numerical studies of the same structure indicated a decrease in flow area during ice conditions, causing an increase in sediment transport above what would occur in the absence of ice (Knack et al. 2010). Hanging dams reduced pool volume and increased near-bed velocities at log-plunge structures on the South Cottonwood Creek, Wyoming, both of which increase the potential for scour (Barrineau et al. 2005). ...
... These effects are likely to impact navigation channel and reservoir maintenance costs and to cause navigation delays for commercial tows (Ettema 2002). Structures can also have an effect on the ice regime of upstream areas themselves, increasing the risk or severity of ice jams and compounding any erosion affects (Knack et al. 2010). In 1984, an ice run on the Coldwater and Nicole Rivers in British Columbia damaged the riprap protection on seven bends due to impact scour (Doyle 1988). ...
Ice in navigation channels and around structures can cause significant damage that requires expensive repairs. This damage can also trigger delays that have the potential to disrupt the entire navigation system, well beyond the reach of the stretches of water directly impacted by ice. One example is upstream of Melvin Price Lock and Dam where ice-induced scour was repaired at a cost in excess of $1,000,000 and the scour hole reappeared within a year of the repair. Therefore, this report outlines the risks to navigation and structures, including a review of the available literature .
... According to Ettema and Kempema (2013), level ice cover elevates flow depths, and thereby decreases flow velocities as well as sediment transportation rates, which is in line with our smooth ice cover simulations. More detailed information of ice effects on shear stress variations in a reach and cross-section scale could be achieved by applying a one dimensional or two dimensional hydrodynamic model (Knack et al., 2010) together with a river ice growth and decay model. The laboratory results of Muste et al. (2000) indicated that TSS load decreases with the increase of cover roughness. ...
A large number of rivers are frozen annually and the river ice cover has an influence on the geomorphological processes. These processes in cohesive sediment rivers are not fully understood. Therefore, this paper demonstrates the impact of river ice cover on sediment transport, i.e. turbidity, suspended sediment loads and erosion potential, compared with a river with ice-free flow conditions. The present sediment transportation conditions during the annual cycle are analysed, and the implications of climate change on wintertime geomorphological processes are estimated. A one-dimensional hydrodynamic model has been applied to the Kokemäenjoki River in SW Finland. The shear stress forces directed to the river bed are simulated with present and projected hydro-climatic conditions. The results of shear stress simulations indicate that a thermally formed smooth ice cover diminishes river bed erosion, compared with an ice-free river with similar discharges. Based on long-term field data, the river ice cover reduces turbidity statistically significantly. Furthermore, suspended sediment concentrations measured in ice-free and ice-covered river water reveal a diminishing effect of ice cover on riverine sediment load. The hydrodynamic simulations suggest that the influence of rippled ice cover on shear stress is varying. Climate change is projected to increase the winter discharges by 27–77 % on average by 2070–2099. Thus, the increasing winter discharges and possible diminishing ice cover periods both increase the erosion potential of the river bed. Hence, the wintertime sediment load of the river is expected to become larger in the future. This article is protected by copyright. All rights reserved.
... The DynaRICE model (Shen et al. 2000) was modified to include the treatment of thermal-ice processes (Liu et al. 2006) including temperature with super-cooling, frazil ice concentration, anchor ice formation and release, surface ice transport, ice cover progression, undercover ice transport, thermal growth and decay of ice covers, and ice cover stability. In the present study, the thermal-ice model is further refined and the model is generalized to include a sediment transport and bed change model (Knack et al. 2010, Knack 2011. A more robust wet-dry bed treatment has been included in the hydrodynamics sub-model to allow for applications to shallow waters (Knack 2011). ...
Hydro-morphological conditions in rivers can change significantly with ice formation, even with minimal changes in discharge. It is important to consider dynamic ice processes and their interactions with channel morphology in a fish habitat model. In this paper, a two-dimensional river ice model on wintertime abiotic physical habitat conditions is presented. The model considers thermal-ice as well as sediment and bed change dynamics in rivers to allow for more detailed habitat suitability evaluation than previous models were capable of doing. Thermal-ice processes modeled include water temperature variation, frazil ice, border ice, cover evolution, ice jam, hanging dam, and anchor ice formation. The substrate quality and availability throughout the winter are modeled by considering the sediment transport and bed changes. The changing hydrodynamic conditions due to the changes in ice and channel bathymetry are determined. Suspended sediment and suspended frazil concentrations can also be monitored simultaneously to identify stressful areas for fish. In the habitat suitability analysis, a PHABSIM type formulation is used. The composite suitability index at each area element in the study domain can be determined. Additionally, the weighted usable area (WUA) can be used to determine the total usable area for each fish species in the study area.
... In this case, the toe region of the jam will contribute to locally increase the sediment transport capacity of the channel for a duration corresponding to the time required for the channel to reach a new bathymetric equilibrium or for the jam to be displaced. As proposed by Knack et al. (2010), river infrastructures can influence the occurrence of ice jamming events and could produce a compound effect on the local bathymetry. ...
... The location and timing of ice jamming and jam-released wave occurrence have received some attention. Although ice jams can form anywhere along a river (Beltaos, 1997), some features are known to promote ice jamming and ice run stagnation such as channel constrictions, enlargements, river bends, islands, confluences, and man-made structures (Andres et al., 2005;Beltaos, 1995;Ettema, 2006;Knack et al., 2010;Sui et al., 2008;Uunila, 1997;Zufelt, 1988). Beltaos and Prowse (2009) suggested that ice jamming could be more severe in steep and wide rivers. ...
This paper presents a comprehensive review of sediment transport in ice-affected rivers by documenting a range of unique ice and sediment transport processes. In cold regions during winter, high sediment transport rates can occur under specific ice conditions, even if the channel discharge is low. River ice directly displaces and carries sediment, and some ice processes can move boulder-sized sediment, contributing to the sculpting of river channels in ways water alone could not. Special attention is directed to the ice breakup period, during which most dynamic ice processes take place and when sediment supply to river channels is maximized. Also discussed are the time and space scales over which ice processes affect sediment transport. Moreover, a global framework that describes the interconnectivity of climate, river discharge, channel morphology, in-stream hydraulics, and sediment transport response is proposed. Within this framework, ice processes are given a central function, as they influence and are affected by sediment transport, hydrological conditions, and channel morphology. A segment of this work reviews and explores the interconnectivity between river ice processes and river discharge as well as between river ice processes and channel morphology. The proposed framework represents a practical tool for a wide range of cold region river scientists and engineers, particularly in light of climate change.
