Existing ice jam theories, which consider the static equilibrium of a floating ice mass in a river, can predict ice jam profiles. These theories, however, cannot be used to describe the transport of river ice and the process of ice jam initiation. In this paper, a theoretical model for the dynamic transport of river ice is formulated. The model can be used to describe the initiation and evolution of ice jams. A one-dimensional numerical scheme is developed for solving the governing equations. A set of numerical examples are presented to illustrate the application of the model and factors that affect the ice jam formation. The analysis shows that ice jams usually occur as a result of ice mass convergence.

Sediment transport and river morphology in cold regions can be significantly influenced by the presence of ice in winter. This paper presents a two-dimensional numerical model on sediment transport coupled with a river ice model. The sediment transport and bed change model is based on recently developed sediment transport formulations under the effect of ice cover. Incorporating changing surface ice dynamics allows the interaction of ice and sediment to be fully realized. Numerical examples are presented that illustrate surface ice effects on sediment transport and bed changes in alluvial channels. These examples include the effects of surface ice runs on sediment transport, sediment transport and bed change in the vicinity of an ice cover front, effect of ice cover breakup, and the interaction of ice jam formation with bed change. Simulation results showed the importance of considering ice effects when studying sediment and channel morphological processes in alluvial rivers.

The stability of riverbanks in cold regions is affected by the freeze-thaw action. The freeze-thaw process causes changes in the moisture content, friction angle, and cohesiveness of the bank material. Together with the freeze-thaw effect, seepage pressure influenced by the changing water levels, and the bank slope are the key factors affecting bank stability. A limit equilibrium bank stability model considering the infiltration water pressure effect is developed and applied to the Shisifenzi section of Inner Mongolia reach of the Yellow River. Laboratory tests of field samples with moisture contents of 15%, 18%, 21%, and saturated showed that the freeze-thaw action reduced the degree of saturation by 34.37 %, 30.71%, 32.48%, and 46.23%, respectively, accompanied by reductions in the internal friction angles by 1.78%, 2.74%, 6.33%, and 5.32%. These changes resulted in a 24.35% to 29.13% reduction in the safety factor of bank stability. Together with seasonal variations in the water levels the field data showed that the bank stability safety factor in the study site increases gradually through the melting period, dry period, wet period, flooding period, and low flow period. The slope stability safety factor increases with the stage of the river but decreases with the groundwater level.

In this study, a numerical model for river ice dynamics (DEMRICE) based on the discrete element method is developed. The ice dynamic component of this model considers moving surface ice floes as discrete elements. It uses a three-dimensional dilated polyhedral discrete element method to resolve contact and external forces on individual ice floes. The hydrodynamic component uses a streamline upwind Petrov–Galerkin (SUPG) finite-element method to solve the two-dimensional unsteady hydraulic equations. The model is validated with the analytical solution for equilibrium ice jams and the DynaRICE model. The ice jam evolution in a straight rectangular channel and the corresponding flow condition changes are simulated and discussed. Finally, the model is applied to simulate the ice transport and cover development in a reach of the Yellow River near Shisifenzi, Inner Mongolia.