上方来水来沙对细沟侵蚀泥沙颗粒组成的影响

Effects of Up-slope Runoff and Sediment on Rill Erosive Sediment Particle Size Distribution

土壤中细颗粒的流失是土壤质量恶化的重要表现之一。利用试验土槽和供沙土槽双土槽径流小区系统,分析了黄土坡面在不同降雨强度、不同含沙水流汇入条件下的细沟侵蚀泥沙颗粒组成变化特征,探讨了降雨强度、坡面上方不同含沙水流汇入、细沟水流流速对细沟侵蚀泥沙颗粒组成变化的影响及其机理。结果表明,上方水流的汇入使侵蚀泥沙中<0 001mm的粘粒含量呈增加趋势,0 05～0 001mm的粉砂粒呈减少趋势,而降雨强度对侵蚀泥沙颗粒组成的影响不甚明显;同时,侵蚀泥沙中粘粒含量随细沟水流流速和细沟侵蚀产沙量的增大而增加。

The fine particle loss in the soil is an important issue of soil quality degradation. A dualbox system, consisting of a feeder box located at upslope and a test box located at down_slope, was used to analyze characteristics of rill erosive sediment particle size distribution with 150 gradients under different rainfall intensities and sediment concentrations in the upslope runoff. Effects of rainfall intensity, upslope runoff with variable sediment concentrations, and rill flow velocity on the rill erosive sediment particle size distribution and the mechanisms were discussed. The results have shown that the upslope runoff discharging into the rill box caused the particles (clay) less than 0001 mm in erosive sediments increase, and 0.05-0.001 mm particles (silt) decrease. Impact of rainfall intensity on rill erosive sediment size distribution was not significant. Meanwhile, the clay content in the rill erosion sediment increases with the rill flow velocity and rill sediment delivery.