Meltwater erosion process of frozen soil as affected by thawed depth under concentrated flow in high altitude and cold regions

Abstract

Changes in thawed depth of frozen soil caused by diurnal and seasonal temperature fluctuations are commonly found in high altitude and latitude regions of the world. These changes significantly influence hydrologic and erosion processes. Experimental data are necessary to improve the understanding and modeling of the phenomenon. Laboratory experiments were conducted in Beijing to assess the impacts of thawed soil depth, slope gradient, and flow rate on soil erosion by concentrated meltwater flow over an underlying frozen soil layer. Soil samples from watershed were filled in flumes, saturated before being frozen. After the soil was completely frozen, flumes were taken out of storage to thaw the frozen soil from top to the designed depths. Meltwater flow was simulated using a tank filled with water and icecubes at approximately 0°C. The erosion experiments involved four thawed soil depths of 1, 2, 5, and 10 cm; three slope gradients of 5°, 10°, and 15°; and three flow rates of 1, 2, and 4 l/min; and seven rill lengths of 0.5, 1, 2, 3, 4, 5, and 6 m. Sediment-laden water samples were collected at the lower end of the flume for determination of sediment concentration. The results showed that sediment concentration increased exponentially with rill length to approach a maximum value. The sediment concentrations were closely correlated with thawed soil depth, flow rate, and slope gradient. Shallower thawed depths delivered more sediments than deeper thawed depths. Slope gradient was the primary factor responsible for severe erosion. The effect of flow rate on sediment concentration which decreased with increasing slope gradient, was not as significant as that of slope gradient. Results from these experiments are useful for understanding the effect of thawed soil depth on erosion process in thawed soils subject to freezing and for estimating erosion model parameters.

Analysis of the Development of an Erosion Gully in an Open-Pit Coal Mine Dump During a Winter Freeze-Thaw Cycle by Using Low-Cost UAVs

“…The snow-thaw runoff of diurnal and seasonal permafrost is the main geomorphic agent in cold, high-latitude and high-altitude regions [1][2][3][4]. Seasonal fluctuations in circulation and temperature lead to daily fluctuations in soil, resulting in the thawing of permafrost and ice, which can significantly alter soil erosion [5].…”

Factors Affecting the Spatial and Temporal Variations in Soil Erodibility of China

“…These intensive human activities have greatly altered the geomorphology and hydrology of the landscape. Previous studies have focused on the effect of land use change (e.g., converting cropland into forest and grassland and sealing off mountainous areas for afforestation) on the k (Fang, ; Ouyang et al, ), the assessment of particular regions (e.g., the Tibetan Plateau, the Loess Plateau, and Karst geomorphology; Ban et al, ; Sun et al, ; Wang & Li, ; Zeng et al, ), mapping (Yao et al, ), and the relationships between the k and soil microbial properties (Gao et al, ; Zhang et al, ). In addition, some studies have used the RUSLE model to calculate the loss due to soil erosion (Feng et al, ; Liu & Fu, ).…”

Experimental Study of Freeze-Thaw/Water Compound Erosion and Hydraulic Conditions as Affected by Thawed Depth on Loessal Slope

“…Wei et al (2015) studied the impacts of FT cycles on runoff and sediment yield of slope land and found that FT cycles greatly increased the sediment yield intensity. In contrast, Ban et al (2017) found that shallower thawed depths delivered more sediments than deeper thawed depths of high altitude and latitude regions. However, few studies have investigated the effects of thawed depth on soil erosion processes in loess slopes under simulated rainfall.…”

“…Zhang et al (2015) found that the critical shear stress was 12.8 Pa under a steep slope accumulation yield experiment (30∼50 • ), while we found that critical shear stress was almost 20 times greater than that obtained in their study at 15 • . Together, these results suggest that FTed soil has a greater erodibility and is less resistant to erosion (Li and Fan, 2014;Ban et al, 2017;Wang et al, 2020).…”