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With the onset of winter in cold regions, border ice begins to form, impacting sediment transport rate and distribution. Understanding the effect of ice cover is crucial in regions with prolonged sub-freezing temperatures, as water bodies remain frozen for a considerable part of the year. While the existing literature includes many studies on sediment transport in open channel flow and several studies on completely ice-covered flow, there is limited research on sediment transport in partially ice-covered channels. Addressing this gap, the current study conducted laboratory experiments in a rectangular flume at the Hydraulics Research and Testing Facility, University of Manitoba, Canada. The investigation focused on examining the influence of asymmetric border ice, varying coverage ratios in asymmetric partially ice-covered flow, and changing flow strengths on bedload transport rate and distribution. Additionally, a comparison was made with symmetric partially ice-covered flow conditions. The findings indicate that the presence of asymmetric border ice indeed affected the bedload transport distribution within the channel, causing non-uniform bedload transport distribution across the channel width, with peak values concentrated in the center of the open flow section. Increased asymmetry in border ice leads to greater asymmetry in bedload transport rate distribution. Despite these pronounced differences in bedload transport rate across the channel width, the cross-section-averaged bedload transport rate could still be estimated utilizing the conventional equations, used for open channel flow, fully ice-covered flow, and symmetric partially ice-covered flow, with the effect of ice cover accounted for by incorporating an additional boundary in the calculation of the wetted perimeter, leading to adjustments in the flow strength. [ABSTRACT FROM AUTHOR]

Cold areas commonly experienced freeze–thaw cycles and covered with rock fragment. Exploring sediment transport capacity of frozen‐stony soil scoured by concentrated meltwater flow is meaningful for soil erosion prediction and modelling in cold regions. This laboratory experiment is conducted to evaluate the contribution of frozen layer and rock fragment to soil erosion, which involves three slope gradients of 5°, 10°, and 15°, three flow rates of 1, 2, and 4 L min−1, four thawed soil depths of 1, 2, 5, and 10 cm, and four rock fragment contents of 0%, 10%, 20%, and 50% on mass basis with rill length of 12 m. Sediment concentration was determined by the soil in runoff at the outlet. An equation is proposed to estimate sediment transport capacity affected by thawed soil depth and rock fragment content by combining exponential and quadratic functions. Model‐fitting results show that sediment transport capacity is negatively correlated with thawed soil depth and exhibits quadratic relationship with rock fragment which peaks at 20% and significantly decreases at rock fragment of 50% on partially thawed slope. Rock fragment takes the leading role of soil erosion on frozen‐stony slope instead of thawed soil depth. Results also indicate that embedded rock fragment on totally thawed soil presents more apparently positive impact at low content, but offers more protection at high content on partially frozen layer. This research reveals the soil erosion mechanisms on frozen‐stony slope and gives guidance for soil conservation in similar hydrologic conditions and soil type. [ABSTRACT FROM AUTHOR]

• Discharge sensitivity to sediment transport capacity was more than slope gradient. • Mean flow velocity was the best hydrodynamic parameter. • The models of sediment transport capacity were established on non-erodible slope. Seasonal soil erosion is a common occurrence in severe cold regions. It is critical to establish the relationship between the sediment transport capacity of a frozen soil slope and its influencing factors. Thus, in this study, a scouring experiment with eight slope gradients (1.5°, 3°, 4.5°, 6°, 7.5°, 9°, 10.5°, and 12°) and six flow discharges (0.15, 0.25, 0.35, 0.45, 0.55, and 0.65 L s−1), was carried out to explore the effects of slope gradient and flow discharge on sediment transport capacity. Then, based on the experiment, sediment transport models were established and verified to quantify the relationships between sediment transport capacity and water erosion factors of overland flow on frozen soil. The results showed that sediment transport capacity increased with increasing slope gradient and flow discharge as a power function (R 2 = 0.983, NSE = 0.970). The sensitivity of flow discharge to sediment transport capacity was more than that of the slope gradient on a non-erodible frozen soil slope. Sediment transport capacity increased in power by increasing the mean flow velocity (R 2 = 0.918, NSE = 0.890). The mean flow velocity was the best hydrodynamic parameter for predicting the sediment transport capacity among stream power (R 2 = 0.894, NSE = 0.911), shear stress (R 2 = 0.823, NSE = 0.818), and unit stream power (R 2 = 0.643, NSE = 0.537). In conclusion, the result of this research is helpful in measuring the sediment transport capacity of non-erodible frozen soil slopes and in investigating the sediment transport process of frozen soil in cold regions. [ABSTRACT FROM AUTHOR]

Concern has been expressed regarding the impacts of climate change on river ice and ice jam formation in cold regions. Ice jams are easily initiated in bends and narrow channels and cause disasters. In this study, observations and remote sensing monitoring are used to study the freeze-up ice jam formation of bends. Sediment transport and freezing process of the river interact, influencing bed changes profile and sedimentary budget. River ice processes, channel evolution, ice hydro-thermodynamics, and ice jam accumulation are explored. The results show that the channel topography determines the river thalweg, and that the channel elevation interacts with the river ice through sediment transport. The channel shrinkage increases the probability of ice jam, and the sharp bend is prone to ice jam formation. Under the effect of secondary circulation flow in the bend and in the outer bank, the juxtaposed freeze-up and the hummocky ice cover occur in the same location, and frazil ice accumulates under the junction of the main channel and the shoals. Affected by the increase of the hydraulic slope and the velocity downstream, open water reaches develops downstream of the ice accumulation. An open water section is emerged upstream of the bend, due to the ice deposition, and partly cut-off supply of the frazil. [ABSTRACT FROM AUTHOR]

• Soil temperature at different depths was measured by sensors. • Thawed soil depth function was deduced based on soil heat conduction mechanism. • The combined function well predicted sediment transport capacity on partially thawed soil. In cold regions, changes in thawed soil depth induced by temperature fluctuation are commonly observed and can affect sediment transport capacity of meltwater flow and erosion processes. In this paper, a method based on laboratory experiment was proposed to predict sediment transport capacity using the thawed soil depth derived from temperature at different soil depths measured during the experimental time period. A saturated soil column with platinum resistance sensors at depths of 5, 10, 15, 20, and 25 cm from the soil surface was placed in a freezer at -25, -20, and -15 °C until it was totally frozen and then placed in an incubator with a constant temperature of 25, 30, and 35 °C. The thawing processes of the frozen soil column were monitored by the sensors that measured temperature during the experimental time. Based on soil heat conduction mechanism, the relations among soil depth, temperature, and time were deduced as a function to predict thawed soil depth giving the frozen temperature, soil temperature inside the incubator, and time after being placed in the incubator. The sediment transport capacity was then calculated by combining the deduced thawed soil depth function and an existing model. The predicted sediment transport capacity was compared with laboratory measurements in literatures. The results show that the model has the ability of predicting sediment transport capacity ranged from 0.019 to 0.598 kg s−1 m−1 with high R2 of 0.99 and 0.98. It suggests that the proposed model can be used to predict the sediment transport capacity by concentrated meltwater flow on different thawed soil slope. This research contributes to our understanding of soil erosion processes by meltwater on partially thawed soil slope. [ABSTRACT FROM AUTHOR]