Study on Infiltration and Soil Moisture Characteristics of a Sand-Covered Slope

By observing the processes of infiltration, flow generation, water flow characteristics and the spatial distribution of erosion in a designed rainfall test, and analyzing the infiltration, flow generation characteristics, water content change characteristics, soil moisture parameters change characteristics, and changes in the spatial patterns of erosion and sediment yield, this study draws the following conclusions: under different rainfall densities, the initial runoff generation time of sand-covered slope is 1~12 min longer than that of loess slope, the initial soil infiltration velocity of sediment-covered slope is about 1.23 times that of loess slope, and the time to reach stable infiltration of loess slope is shorter than that of sediment-covered slope. Under different rainfall densities, the rising time of the water content curve of sand-covered slope is earlier than that of loess slope. For the same duration of rainfall, the vertical infiltration performance of soil water of sand-covered slope is higher than that of loess slope, and when the rainfall density on the slope increases by 0.5 mm/min, the increase in runoff shear stress of the sediment-covered slope is about 1.5 times that of the loess slope, and the runoff power is about 1.13 times that of the loess slope

Influence of Check Dams on Flood and Erosion Dynamic Processes of a Small Watershed in the Loss Plateau

As an important soil and water conservation engineering measure, check dams have been constructed on a large scale in the Loess Plateau of China. However, their effects on runoff and sediment processes in the basin are still unclear. In this study, the hydrodynamic processes of the Wangmaogou watershed located in the Loess Plateau were simulated, and the influence of check dams on the flood and erosion dynamic processes in this watershed were also evaluated. The results showed that the check dams obviously reduced the flood peak and flood volume and mitigated the flood process. After the dam system was completed, the flood peak and flood volume were reduced by 65.34% and 58.67%, respectively. The erosion dynamic distribution of the main channel in the small watershed was changed to different extents by the different dam type combinations, and the erosion dynamic parameters of the channel decreased most after the dam system was completed, when the velocity and runoff shear stress of the outlet section were reduced by 10.69% and 31.08%, respectively. Additionally, the benefits of sediment reduction were most obvious after the check dam system was completed, with the sediment discharge in the watershed being reduced by 83.92%. The results of this study would provide specific implications for construction and management of check dams in the Loess plateau

Response of the Meltwater Erosion to Runoff Energy Consumption on Loessal Slopes

Soil properties are influenced by freeze-thaw, which in turn influences soil erosion. Despite this, only a few studies have investigated the impacts on soil hydrodynamic processes. The objective of this study was to evaluate the impact of soil freezing conditions on runoff, its energy consumption, and soil erosion. A total of 27 laboratory-concentrated meltwater flow experiments were performed to investigate the soil erosion rate, the runoff energy consumption, and the relationship between the soil erosion rate and runoff energy consumption by concentrated flow under combinations of three flow rates (1, 2, and 4 L/min) and three soil conditions (unfrozen, shallow-thawed, and frozen). The individual and combined effects of soil condition, flow rate, and runoff energy consumption on the soil erosion rate were analyzed. For the same flow rate, the shallow-thawed and frozen slope produced mean values of 3.08 and 4.53 times the average soil erosion rates compared to the unfrozen slope, respectively. The number of rills in the unfrozen soil slope were 4, 3, and 2 under the flow rate of 1, 2, and 4 L/min, respectively. The number of rills in the thawed-shallow and frozen soil slope were all 1 under the flow rate of 1, 2, and 4 L/min. The rill displayed disconnected distribution patterns on the unfrozen slope, but a connected rill occurred on the shallow-thawed and frozen slopes. The average rill width on unfrozen, thawed-shallow, and frozen soil slopes increased by 1.87 cm, 4.38 cm, and 1.68 cm as the flow rate increased from 1 L/min to 4 L/min. There was no significant difference in the rill length on the frozen slope under different flow rates (p > 0.05). The runoff energy consumption ranged from unfrozen > shallow-thawed > frozen slopes at the same flow rate. The soil erosion rate had a linear relationship with runoff energy consumption. The spatial distribution of the runoff energy implied that soil erosion was mainly sourced from the unfrozen down slope, shallow-thawed upper slope, and frozen full slope