| 摘要: |
| 【目的】 探讨雨滴打击下薄层漫流的输沙机理，为建立细沟间薄层水流泥沙输移预报模型提供理论依据。【方法】 采用人工模拟降雨试验，以无雨滴打击为对照，对黏性土壤在直径2.68 mm和3.02 mm雨滴击溅作用下，不同坡度坡面（2°和4°）细沟间薄层水流深度（h）与土壤侵蚀量、泥沙含沙量、扰动系数（Cr）关系进行了研究。建立了黄土缓坡坡面扰动系数的预测方程。【结果】 雨滴击溅下坡面薄层水流土壤侵蚀量较无雨滴击溅时显著增大，击溅雨滴直径越大，侵蚀量越大，与水深呈对数规律变化。在雨滴击溅作用下，泥沙含沙量随水深的增加呈减小趋势，且雨滴直径越大，减小幅度越大，这与无雨滴击溅时薄层水流的泥沙含沙量变化相反，表明雨滴击溅作用是薄层水流泥沙输移的主要动力。雨滴击溅作用对薄层水流的扰动系数随水流深度的增大呈线性减小趋势；对侵蚀性黄土而言，2.68 mm雨滴击溅下，无扰动水深为6.94 mm；3.02 mm雨滴击溅下，无扰动水深为7.20 mm。【结论】 雨滴击溅作用是薄层水流泥沙剥蚀的主要动力。 |
| 关键词: 薄层漫流 雨滴击溅 泥沙输移 泥沙含沙量 扰动系数 |
| DOI： |
| 分类号: |
| 基金项目:教育部留学回国启动基金项目（14110105）；西北农林科技大学校长基金项目（08080202） |
|
| The mechanics of sediment transport under raindrops impacting shallow overland flowL |
|
|
| Abstract: |
| 【Objective】 This study had an important significance to set up the predicted model fallow overland flow on the Loess Plateau.【Method】 Using the artificial rainfall,this paper studied the mechanics of sediment transport under raindrops impacting shallow overland flow.The equation was constructed to predict the disturbed coefficient of fallow overland flow by raindrops impact to yellow loam.【Result】 Sediment detachment rate of sloping fallow overland flow by raindrops impact was higher than that under no raindrops to cohesive soils,the larger the raindrop diameter,the higher the sediment detachment rate,and it had a logarithmic correlation with the depths of sloping fallow overland flow under raindrops impact.Sediment concentrations under raindrops impact decreased as depths of sloping fallow overland flow increased,by contrary,under no raindrops impact sediment concentrations increased as depths of sloping fallow overland flow increased.It indicated the raindrops impact was the drive power for sediment detachment of sallow overland flow.The disturbed coefficients for fallow overland flow under raindrops impact decreased with linear relationship as the depths of shallow overland flow increased;to erosive yellow loam,the non disturbed depth for fallow overland flow was 6.36 mm under the diameter 2.68 mm raindrops impact,and so was 7.20 mm under the diameter 3.02 mm raindrop.【Conclusion】 Raindrop impact is the main power to conduce the sediment detachment of fallow overland flow. |
| Key words: fallow overland flow raindrop impact sediment transport sediment content disturbed coefficient by raindrop |
