A Numerical Model for Ice Influenced Sediment Transport and Bed Change

English Abstract:

The presence of surface ice has significant effects on sediment transport and channel morphology. Studies on the interaction of sediment transport and surface ice are limited although it can be a significant period of bed change for rivers in cold regions. An improved understanding of the interaction of surface ice and sediment transport processes is essential for river engineering and morphological studies. This paper presents a two-dimensional coupled hydro-thermal-ice-sediment river dynamics numerical model. The ice model component considers the dynamics of ice transport and ice cover evolution, as well as thermal processes. The thermal component includes water temperature, frazil ice, anchor ice, and the thermal growth and decay of ice cover. The sediment transport and bed change model considers the effect of surface ice and water temperature on sediment transport capacity. The sediment transport equations were developed from an analysis of data from existing flume experiments, each with a limited range of flow, ice, and sediment transport conditions. The analysis showed that by expressing the flow strength in terms of the bed shear stress, bed load transport can be described by conventional relationships for the equivalent free-surface flow. It was also found that suspended sediment transport rates can be calculated using a modified Rouse formulation which considers the effect of surface ice on flow velocity and diffusion coefficient. Examples of simulations using the numerical model illustrating the ice effects on sediment transport and bed changes in ice influenced alluvial channels are presented.