黄土土质对溅蚀特征的影响

Effects of Loess Soil Texture on Raindrop Splash

土壤质地是土粒溅蚀量及溅出方式的重要影响因素。以黄土高原4种土壤（土、黑垆土、砂黄土、黄绵土）为试验用土,通过人工模拟降雨试验研究了黄土土质对溅蚀量、溅出土粒颗粒组成的影响。结果表明：（1）溅蚀量随降雨历时增加呈幂函数趋势增加。降雨开始时溅蚀量取决于土表松散颗粒含量及土粒均匀程度。随后溅蚀量增加速率则取决于黏粒（〈0.002mm）、细粉粒（0.002～0.02mm）及吸湿性黏土矿物含量,二者综合作用使得溅蚀量增加幅度减小。（2）溅蚀过程中溅出土粒的粒径组成决定于供试土壤的颗粒组成,〉0.25mm颗粒含量高的土壤溅出土粒粒径分布均匀,而〉0.25mm颗粒含量低的土壤溅出土粒集中分布于粗粉粒、细砂粒粒级内。（3）通过溅出土粒实际与原始颗粒含量的比值可判断土壤颗粒溅出方式。供试土壤黏粒、细粉粒、粗粉粒（0.02～0.05mm）的实际与原始颗粒含量比值〈1,均以团粒形式溅出,不受土壤类别影响;而土、黑垆土砂粒的实际与原始颗粒含量的比值〉1,以团粒形式溅出;砂黄土、黄绵土土壤砂粒实际与原始颗粒含量比值≈1,以单粒形式溅出。

Soil texture is one of the important factors on raindrop splash erosion and the form of particles splashed out.Rainfall simulation experiments with four loess soils of Lou soil,dark loessial soil,sandy loess,loessial soil,were performed to evaluate effects of soil texture on raindrop splash erosion and splashed particle size distribution（PSD）.The results showed that：（1）power function were the best function to describe the splash erosion increases with the rainfall duration,at the beginning of rainfall,the raindrop splash erosion depends on the amount of loose particles on soil surface and the soil particle uniformity,and then the increase rate of raindrop splash erosion depends on the content of clay（0.002 mm）,fine silt（0.002~0.02 mm）and hygroscopicity clay mineral,the combination makes the increase amplitude of raindrop splash erosion decrease;（2）on the process of raindrop splash,the particle composition of splashed soil particle was determined by the particle composition of experimental bulk soil,if the content of coarse sand（0.25mm）in bulk soil was high the splashed soil had uniform distribution of particle sizes,otherwise when the content of coarse sand in bulk soil was low,the splashed soil particle concentrated distribution in coarse silt and fine sand;（3）the ratio of the splashed undispersed PSD and dispersed PSD revealed the form of particle splashed out,the undispersed/dispersed PSD ratios of clay-sized,fine-silt-sized and coarse-siltsized particles for four experimental soils were less than 1,indicating that they were splashed out as aggregate,the undispersed/dispersed PSD ratios of sand-sized for Lou soil and dark loessial soil were more than 1,they were splashed out as aggregate,while the undispersed/dispersed PSD ratios of sand-sized for sandy soil and loessial soil were close to 1,they were splashed out as single grain.