Hydrodynamics process of soil erosion and sediment yield by runoff on Loess Slope
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摘要: 通过室内模拟冲刷试验系统研究了3°~30°坡度范围内坡面径流的侵蚀动力及产沙特征,分析了坡面径流能耗与径流侵蚀产沙之间的关系。结果表明,坡面径流平均流速随坡度和流量的增加而增大,流速与坡度和流量之间存在指数函数关系,坡度对流速的影响大于流量。在3°~21°坡度范围内,坡面径流单宽能耗随坡度的增加而增加,当坡度超过21°时,径流能耗随坡度的增加而降低。坡度对侵蚀产沙的影响也有类似的现象,在3°~21°坡度范围内,坡面径流平均单宽输沙率随坡度的增加而增大,当坡度达到临界极值21°和24°后,坡面径流平均输沙率随坡度增加而减小;在整个试验坡度范围内,径流平均单宽输沙率随流量的增大而增大;流量对坡面径流平均单宽输沙率的影响大于坡度。坡面径流平均单宽输沙率和单宽径流能耗之间存在明显的线性关系,其临界单宽径流能耗随坡度的增加而增加,土壤可蚀性参数随坡度的变化在10.368~30.366的范围变化,试验的土壤可蚀性的平均值为14.61。Abstract: Based on a series of the runoff scouring experiments on slopes with their gradient ranging from 3° to 30°,the runoff energy consumption and the sediment yield is analyzed.The results show that the average flow velocity increases with the flow discharge and the slope gradient in an exponential form,and the slope gradient has greater effect on velocity than discharge.On the slope of 3°~21°,the average runoff consumption increases with slope,and decreases with slope when the slope gradient is over the critical gradient (21°~24°).The similar trends exist in the relation between the average sediment transport rate and slope.On the slope of 3°~21°,the average sediment transport rate increases with slope,and decreases with slope when the slope gradient is over the critical gradient (21°~24°).The average sediment transport rate increases with the increase of the runoff discharge,which has greater effect on the sediment yield than slope.Further the analysis indicates that there is a linear relation between the sediment transport ratio of the unit runoff width and the energy consumption of the unit runoff width.The critical energy consumption of the unit width increases with slope,while the soil erodibility decreases with the increase of slop e,whose value varies from 10.369 to 30.366,and the average value is 14.61 in the experiment across all slope.
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Key words:
- runoff scouring /
- energy consumption /
- sediment transport rate /
- loess slope /
- soil erosion /
- sediment yield
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