天然降雨下紫色土和第四纪红黏土坡面侵蚀过程研究

选取南方红壤区紫色土和第四纪红黏土两种典型土壤类型，通过天然降雨试验，在同等试验条件下对紫色土和第四纪红黏土两种土壤的坡面侵蚀过程中径流量变化、产沙量变化、土壤团聚体以及粒径分析来阐述我国南方红壤区的土壤坡面侵蚀过程。结果表明:（1）降雨是造成土壤坡面产生径流的主要原因，随着降雨的不断增大，土壤坡面径流量不断的增加，紫色土的总径流量较第四纪红黏土大。（2）雨强是造成土壤坡面产沙量的主要原因，特别是在中雨强降雨和大雨强降雨时，土壤侵蚀泥沙量的产生比较明显，紫色土与第四纪红黏土的土壤侵蚀泥沙量比例关系为:1.14∶1.0。（3）紫色土和第四纪红黏土均以 < 0.25 mm的微团聚体占优势，均占65%以上，而紫色土达到90%之多，紫色土微团聚体流失较第四纪红黏土严重。（4）通过两种土壤的降雨前后土壤颗粒对比分析，紫色土减少的土壤颗粒主要是黏粒和粉粒，砂粒相对增加，变化量大，而第四纪红黏土相对较少。

Research for Purple Soil and Quaternary Rred Clay Soil Erosion Process on Hillslope Under Natural Rainfall

Purple soil and quaternary red clay soil two typical soil types in red soil zone of southern China were selected. Through natural rainfall experiments, under the same test conditions, changes in runoff and sediment yield, soil aggregates and particle size of purple soil and quaternary red clay soil the two kinds of soil parent material slope erosion were analyzed in order to illustrate the process of soil erosion on the slope in red soil region of southern China. The results showed: (1) rainfall is the main cause of slope runoff, with increasing rainfall, runoff constantly increases, runoff rate is greater in Ppurple soil than Quaternary red clay soil; (2) rainfall intensity is the main cause of slope sediment yield, especially in heavy rainfall during moderate and heavy rain soil erosion and sediment generation were more obvious, the ratio the amount of soil erosion and sediment bentween purple soil and quaternary red clay soil is 1.14∶1.0; (3) < 0.25 mm micro-aggregates in purple soil and quaternary red clay soil are dominant, accounting for more than 65%, while 90% for purple soil, purple soil micro-aggregates were more severely loss than the quaternary red clay; (4) by comparing the two types of soil particles before and after rainfall analysis of soil, reduced soil particles of purple soil are clay and silt particles, the relative increase was found in the sand particle, changes were large, but clay content in qauaternary red is relatively little.