陕北多沙区乡村聚落水蚀泥沙粒度分布研究

Particle-size distribution of erosion sediment of erosion soil of rural settlements in more sediment area of Shaanxi Province

目的 分析研究陕北多沙区乡村聚落水蚀泥沙分布规律，探讨乡村聚落的土壤侵蚀问题，为加强该区的水土流失治理提供理论依据。方法 建立乡村聚落径流、泥沙观测小区，根据观测的降雨径流泥沙数据资料，在粒度分析实验室用英国生产的Mastersizer—S型粒度仪测定样品粒度，对侵蚀泥沙样品进行粒度分析。结果 陕北乡村聚落侵蚀泥沙的粒径分布呈“M”型，有2个明显的波峰，分别是10-50μm的粗粉沙和1～5μm的粘粒，其中粗粉沙的含量最多，达到了40％左右，粘粒的含量次之，达到了20％左右，二者的含量总共达到了60％以上；但是，通过对庭院、户间道路和户间空地的侵蚀泥沙在相同降雨条件下进行分析发现，侵蚀泥沙粒度在共性之中却有一定的差异性：在相同的降雨强度下，侵蚀泥沙粒径中〈5μm细颗粒的含量以户间道路最少，庭院和户间空地次之，而〉50μm颗粒的含量却以户间道路为最多，庭院和户间空地次之。结论 陕北多沙区侵蚀泥沙中主要是粗粉沙和粘粒物质；户间道路径流挟沙能力最大，侵蚀强度也最大，可携带走较多的粗颗粒泥沙，和较少的细颗粒泥沙；而庭院和户间空地径流挟沙能力最小，携带走的是大量的细颗粒泥沙，粗颗粒泥沙较少。这说明在加强治理黄土高原乡村聚落中土壤侵蚀的同时，聚落中户间道路的土壤侵蚀问题应不可忽视。

Aim To analyze the particle-size distribution of erosion sediment among courtyards, roads and open space between house and courtyards in more sediment of northern Shaanxi province. Methods Based on the data of Erosion Soil of Rural Settlements in More Sediment Area of Shaanxi Province, using the instrument of Mastersizer-S to measure the Particle-Size Distribution. Results It is showed that the shape of particle-size distribution is most like the English letter ＂M＂, and the percentage of coarse silt （10-50 μm） and clay fraction （1-5μm） is higher than the other in Yulin, Suide and Yan＇an. But it is presented that particle-size distribution exists the divergence in commonness when under the same rain intensity. The percentage of 〈5 μm clay fraction in roads is smaller than courtyards and open space, but the percentage of 〉50 μm coarse silt in roads is larger than that of courtyards and open space. Conclusion It is showed that the roads between house and courtyards have the strongest capacity to transport more coarse silt, so that on the roads there have the biggest erosion intensity. The courtyards and open space have less capacity to transport more coarse silt because the flat gradient. So they transport more clay fraction in sediment, and have less erosion intensity. The soil erosion of roads between house and courtyards should not be ignored during the control of soil erosion in Loess plateau.