含碎石紫色土坡面降雨入渗和产流产沙过程

在室内土槽模拟降雨试验基础上，观测了具有不同碎石体积含量紫色土的降雨入渗地表产流产沙量以及细沟间径流和细沟径流的流速，以期建立碎石含量与土壤流失的定量关系。研究结果表明:土壤中碎石混合对降雨入渗有正负两方面的影响，当碎石含量为20%~30%时，碎石的存在增强土壤入渗能力，当碎石含量提高到30%时，土壤的入渗能力被削弱。土壤中碎石混合通过不同的作用机制对坡面细沟间径流流速和细沟径流流速产生不同的影响，随着碎石含量的增加，细沟间径流平均流速逐渐增加，细沟径流的平均流速逐渐降低。土壤中碎石混合通过改变土壤的物质组成和结构，增强土壤的抗蚀性和抗冲性，随着碎石含量的增加，径流含沙率和土壤流失量显著降低，土壤流失比与碎石含量呈极显著指数负相关关系。

Processes of rainfall infiltration,runoff and sediment yield on purple soil slope containing rock fragments

Based on indoor rainfall simulation tests carried out with a soil bin, measurements are made for various physical processes including the rainfall infiltration, the surface runoff, the sediment yield, the velocity of interrill flow and the velocity of rill flow on the purple soil slop containing different rock fragment contents. The quantitative relation between rock fragment content and soil loss is thus established. Result show that soil mixed with rock fragments can have both positive and negative influences on rainfall infiltration. The infiltration capacity of soil is enhanced when the content of rock fragments less than 20%~30%, while the capacity will be reduced after the content reaching 30%. Through different action mechanisms, soil mixed with rock fragments has different influences on velocity of interrill flow and velocity of rill flow. The increase of the rock fragment content can lead to an increase in the mean velocity of interrill flow, while decreasing that of rill flow. Through altering the composition and structure of soil, soil mixed with rock fragments can improve both soil anti-erodibility and anti-scouribility. With increasing of rock fragment content, values of sediment concentration and sediment yield will be decreased significantly. The relationship between rock fragment content and soil loss ratio can be expressed by a negative and exponential function with a high degree of reliability.