雨强对华北土石山区坡面侵蚀及其颗粒富集过程的影响

为研究雨强对华北土石山区坡面侵蚀过程和泥沙颗粒分布规律的影响,采用室内人工模拟降雨试验,以华北土石山区2种典型土壤为研究对象,在4种雨强(30,60,90,120mm/h)条件下,分析了径流的变化过程和侵蚀泥沙的颗粒组成及其颗粒富集率的变化规律。结果表明:(1)随着雨强从30mm/h增大至120mm/h,黄土性褐土和石灰性褐土的产流时间均逐渐减小,分别缩短了79%和85%;(2)在60,90,120mm/h雨强条件下,黄土性褐土的径流强度和泥沙浓度均随降雨时间先减小后增大,而后趋于稳定状态,石灰性褐土仅在120mm/h雨强条件下出现相似规律;(3)当雨强从30mm/h增大至120mm/h,黄土性褐土泥沙流失朝粗颗粒化发展,侵蚀泥沙的砂粒和粗粉粒含量分别增加了86%和21%,而石灰性褐土的变化不明显;(4)在降雨初始阶段,粒径较小的黏粒和细粉粒明显富集,而粒径较大的粗粉粒和砂粒不易流失,但随着降雨历时的延长,不同粒径泥沙颗粒的富集率趋于1,这种现象在大雨强下表现得尤为明显。

Effects of Rainfall Intensity on Slope Erosion and Sediment Particles Enrichment Process in the Rocky Mountain Area of North China

In order to research the impact of rainfall intensity on slope erosion process and distribution of sediment particles in the rocky mountain area of North China,two typical soils from this area were selected,and the variation of runoff,the composition of particles and the enrichment rate of particles in erosion sediment were analyzed under 4 different rainfall intensities (30,60,90,and 120 mm/h) through rainfall simulation experiments in laboratory.The results were as follows:(1) With the rainfall intensity increased from 30 mm/h to 120 mm/h,the time producing runoff decreased by 79％ and 85％ for the loess cinnamon soil and calcic cinnamon soil,respectively;(2) Under the 60,90,and 120 mm/h rainfall intensity,runoff intensity and sediment concentration of the loess cinnamon soil decreased first and then increased with rainfall time extending,and then tended to be stable,while runoff intensity and sediment concentration of calcic cinnamon soil appeared similar trend only under 120 mm/h rainfall intensity;(3) When the rainfall intensity increased from 30 mm/h to 120 mm/h,the content of coarse particle increased in the lost sediment for the loess cinnamon soil,and the contents of sand and coarse silt increased by 86％ and 21％,respectively.However,there was no obviously change for the calcic cinnamon soil;(4) In the initial stage of rainfall,the clay and fine silt enriched obviously,and the coarse silt and sand were not easy to be lost,while with the extending of rainfall the enrichment rate of different sediment particles gradually approached to 1,especially under heavy rain.