典型薄层黑土区前期坡面水蚀对土壤风蚀的影响

为了探究东北黑土区水力风力叠加作用的多营力复合侵蚀机理,该研究利用直流吹气式风洞对有、无前期降雨的地表进行风蚀试验,对比分析前期坡面水蚀作用对黑土区坡耕地土壤风蚀的影响。结果显示:不同降雨强度下前期坡面水蚀作用使土壤风蚀量明显减小,即前期坡面水蚀作用对地表产生了明显抗风蚀效应。在9、12和15 m/s风速作用下,50和100 mm/h降雨强度的前期坡面水蚀作用产生的抗风蚀效率分别为68.4%～96.2%和77.2%～97.6%,且随降雨强度增加,其抗风蚀效率增大。土壤风蚀强度受前期坡面水蚀作用中降雨强度和风蚀作用风速的综合影响,降雨强度的增加对土壤风蚀的抑制效果明显。前期坡面水蚀作用降低了土壤风蚀输沙量和输沙高度,且风蚀输沙量随前期坡面水蚀作用中降雨强度的增大而减小。前期坡面水蚀作用对地表产生抗风蚀效应的主要原因一方面是前期降雨径流侵蚀作用对土壤的压实过程改变了土壤性质和地表形态,使地表土壤抗剪强度和土壤紧实度增加,从而提高了土壤结构的稳定性和抗风蚀能力;另一方面前期降雨侵蚀作用使地表土壤颗粒分散并随径流流失,减少了后期土壤风蚀的物质来源,抑制了土壤风蚀的发生。该研究结果不仅揭示了前期坡面水蚀作用对黑土区土壤风蚀的影响机制,也为针对性防治黑土坡面复合侵蚀和黑土资源的可持续利用提供了理论依据。

Effect of previous sloping water erosion on soil wind erosion in typical thin layered Mollisol region

Abstract: The sloping farmlands in the Mollisol region of northeast China have the characteristics of multi-agent compound soil erosion followed by snow-melt runoff erosion and then wind erosion in spring. However, the current researches on compound soil erosion in this region are still rather weak, which affects the accurate implementation of the prevention and control measures of compound soil erosion. This paper applied an approach of combining indoor simulated rainfall experiment with wind tunnel simulation experiment to analyze previous sloping water erosion effects on the soil wind erosion in the Mollisol region of northeast China. The results showed that the amount of soil wind erosion significantly reduced after the previous sloping water erosion at 50 and 100 mm/h rainfall intensities, i.e., previous sloping water erosion action produced obvious an anti-wind erosion effect. Under 50 and 100 mm/h rainfall intensities, the anti-wind erosion effects under 9, 12 and 15 m/s wind speeds were 68.4%-96.2% and 77.2%-97.6%, respectively; with an increase of rainfall intensity, the anti-wind erosion effect increased. The soil wind erosion rate after previous sloping water erosion action was comprehensively affected by the rainfall intensity in previous sloping water erosion and wind velocity in later soil wind erosion. With increasing of rainfall intensity, the inhibiting effect of soil wind erosion caused by previous sloping water erosion action was greater. The previous sloping water erosion action reduced wind erosion delivery and its height, and wind erosion delivery decreased with the increase of rainfall intensity of the previous sloping water erosion. The main reasons for the anti-wind erosion effect caused by the previous sloping water erosion were that the soil compaction processes caused by previous sloping rainfall and runoff altered soil physical-mechanic properties and surface morphology, which caused an increase of surface soil shear strength and soil hardness, and then enhanced soil structure stability and anti-wind erosion ability, and inhibited wind erosion occurrence. The research findings of this study not only reveal the mechanism of previous sloping water erosion affecting soil wind erosion in the Mollisol region of northeast China, but also provide a theoretical basis for preventing compound erosion and sustainably utilization of Mollisol resources.