坡面土壤侵蚀临界坡度问题的理论与实验研究  

Theoretical Analysis and Experimental Study on the Critical Slope of Erosion

作　　者：胡世雄 靳长兴[1,2] 

机构地区：[1]国际泥沙研究培训中心 [2]中国科学院地理研究所

出　　处：《地理学报》1999年第4期347-356,共10页Acta Geographica Sinica

基　　金：国家自然科学基金;国家基金委与水利部联合资助项目

摘　　要：本文首先在分析坡度对坡面流及坡面侵蚀的基础上，运用能量法及泥沙运动力学两种方法从不同理论角度探讨了坡面土壤侵蚀临界坡度问题；其次，通过室内外实验观测资料，结合与其他学者观点的比较分析，最后得出结论：坡面侵蚀以溅蚀为主时，临界坡度应小于２２°；以面蚀为主时，临界坡度为２２°～２６°左右；以沟蚀为主时，临界坡度会超过３０°；若以重力侵蚀为主，临界坡度可能会更大。The overland flow is defined as the flow of water over the land surface toward a stream channel and is the initial phase of surface runoff. The sediment yielding from overland flow erosion increases with the increasing slope if the slope is smaller than a critical value, and reduces following further increase of the slope if the slope is larger than the critical slope. With Energy Theory, Sediment Transportation Mechanism and data from laboratory and field experiments, the critical slope of overland flow erosion was studied in detail. Firstly, from the viewpoint of energy analysis, the detachment capacity of overland flow is directly proportional to the flow shear stress, and the shear stress is directly proportional to the kinetic energy of overland flow. A theoretical formula is derived which indicated that the energy of overland flow is closely related to the flow rate per unit width, composition of soil particle size, runoff depth and slope gradient. The maximum flow shear stress occurs if the slope is between 22° and 26°. Therefore, the conclusion from the energy analysis is obtained that the critical slope of overland flow erosion is about 22°￣26°. Secondly, the analysis from dimensionless shear ratio and sediment transportation mechanism shows that the capacity of overland flow carrying sediment reach its maximum at the slope gradient approximate to the frictions angle of sediment under water. The sediment carried by overland flow is mainly composed by the silt and fine sand, whose friction angle under water is measured at 22°￣27°. This means that critical slope of over land erosion is between 22°￣27°, which is coincident with the critical slope derived from energy analysis. Thirdly, simulation experiment in laboratory shows that the maximum sediment yield is obtained at the slope of 23°￣27°, which verified the result induced from the theoretical analysis. Finally, it is concluded that the critical slope gradient of sheet erosion and rill erosion is about 22°￣27°, and that of rai

关 键 词：坡面土壤侵蚀 临界坡度 能量 实验研究 

分 类 号：S157.1[农业科学—土壤学] P931.92[农业科学—农业基础科学]