土壤分离能力测定的不确定性分析

Uncertainty Analysis of Soil Detachment Capacity Measurement

土壤分离能力是含沙量为零时坡面径流分离土壤的最大值,是确定细沟可蚀性和土壤临界剪切力的基础,也是土壤侵蚀过程模型推广应用的前提,因此,对其准确测量非常关键。在系统分析野外坡面径流小区无法测定土壤分离能力的基础上,从室内试验水槽的类型与规格、土样采集的代表性、测试样品的长度、扰动程度、初始土壤含水量及土样冲刷时间等方面,系统讨论了它们对土壤分离能力的潜在影响与机制,探讨了土壤分离能力测定过程中的不确定性。对深刻理解土壤侵蚀过程的动力机制、选择合理的土壤分离能力测定方法与试验过程,具有重要的指导意义。

Soil detachment capacity is the maximum soil detachment rate when sediment concentration of overland flow is zero. It is the foundation of the determination of rill erodibility and soil critical shear stress, and wide application of the process--based soil erosion models. A detailed analysis indicated that runoff plot could not be used to measure soil detachment capacity by overland flow. The potential effects on soil detachment capacity and their mechanisms were fully discussed in the aspects of the type and size of hydraulic flume, representation of soil sampling, length of soil sample, disturbance of soil sample, initial soil moisture, and duration of flowing water scouring. The uncertainties in soil detachment capacity measurement were systematically analyzed. This paper is helpful to understand the dynamic mechanism of soil erosion processes, and to choose the rational methods and experimental procedures to measure soil detachment capacity by overland flow.