2次降雨条件下不同土壤细沟侵蚀分析

Analysis of two kinds soil rill evolution under the secondary rainfall

不同土壤细沟侵蚀发育对比研究是探讨细沟侵蚀机制的必要内容。通过间隔为24 h的2次人工模拟降雨,在不同降雨强度(1.5,2.0,1.0 mm/min)、不同坡长(5、10 m)的试验条件下,分析坡度为20°时塿土和黄绵土2种土壤细沟侵蚀过程中产流产沙、空间变化的差异。结果表明:1)从坡面产流量来看,2种土壤在2次人工降雨过程中有相似的产流过程,坡长和降雨强度相同时,塿土坡面产流量大于黄绵土;2)从坡面形态看,第1场降雨过程中塿土坡面表面积、细沟侵蚀强度大于黄绵土坡面,但黄绵土坡面一旦发生细沟侵蚀,其体积变化幅度剧烈于塿土坡面;3)塿土在第1场降雨过程中侵蚀速率的变化过程可以反应细沟发育的各个阶段,较大降雨强度使黄绵土发生细沟侵蚀侵蚀,其细沟发育的各个阶段持续时间长于塿土,即黄绵土细沟形态变化缓慢。

It is necessary to study different soil rill erosion for investigating rill erosion mechanism. In this paper, the secondary simulated rainfall experiments with an interval of 24 hours were conducted, with different slope lengths （5,10 m） and different rainfall intensities （1.5,2.0,1.0 mm/min）, to study the differences of runoff and sediment yield and rill space about 2 kinds soil rill erosion developments. Results showed that two kinds of soil shared similar runoff process. At the same rainfall intensity and slope length, lou soil slope surface runoff was greater than the loessial soil. In the first rainfall, the slope surface area and rill erosion intensity of lou soil was greater than the loessial soil. Once the rill erosion occured in the loessial soil slope surface, the volume variations of loessial soil was strongly than lou soil. The change process of the erosion rate could reflected lou soil rill stages of development. Rill erosion would happen with larger rainfall intensity in the loessial soil, and the duration time for stages was longer than lou soil, i. e. , Loessial soil rill morphological changed slowly.