In order to determine the main hydrodynamic erosion factors that affect the soil detachment rate and establish the predicting model about soil erosion on freeze-thaw slope, the experiment study, involving 2 slopes (10° and 15°), 4 thaw depths (2, 5, 8 and 11 cm) and 2 flow rates (3 and 9 L/min), was carried out under the circumstances of scouring the slopes outdoors. In order to avoid the influence of the rainy season, the slopes had been paved and completed in October, for which the rainy days had past. The experimental indices were measured by different approaches, for instance, the staining method was utilized to measure the flow velocity; the runoff width could be measured through using a ruler at 9 positions; the thaw depth was measured by using a measuring needle. The whole process of this experiment lasted for about 15 min so as to avoid the deeper freezing level melting too much, which could affect the experiment result, for the longer the experimental process lasted, the deeper the frozen layer would melt under the function of the scouring power. The discharged sediment was collected at the end of the scouring trough and the frequency of collecting was once per minute. The changing tendency of soil detachment rate with the flow rate, slope, and thaw depth was discussed. Then, the relationships between the soil detachment rate and the hydrodynamic erosion factors (average runoff depth, shear stress, stream power, and unit stream power) were analyzed. Finally, the theory of stepwise regression analysis was adopted to build the soil erosion predicting model. The results of this experiment indicated that under the same thaw depth, the soil detachment rate increased with the increasing of the slope and flow rate; when scouring the same slope at the flow rate of 3 L/min, the most serious soil detachment occurred at the original thaw depth of 5 cm, and the soil detachment rate was decreasing gradually along with the increase of the original thaw depth; when the flow rate was kept at 9 L/min, the soil detachment rate had a tendency of increasing with the original thaw depth increasing. Besides, the correlation relationships between soil detachment rate and hydrodynamic erosion factors (shear stress, stream power, and unit stream power) were positive linear correlation (P<0.01), and the factor of stream power was more obvious than other factors. And the predicting model, which was based on the stream power and thaw depth, was also established.
soilsslopeerosionfreeze-thaw effectoriginal thaw depthstream power
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