风水交错侵蚀条件下侵蚀泥沙颗粒变化特征

Impact of wind-water alternate erosion on the characteristics of sediment particles

风蚀和水蚀是黄土高原风蚀水蚀交错区土壤侵蚀的主要方式，研究风水交错侵蚀对土壤颗粒的影响对于准确评价该区土壤质量及环境影响有重要意义.本文采用风洞与模拟降雨试验相结合的方法，分析了风水交错侵蚀条件下侵蚀泥沙颗粒变化特征.结果表明： 在11、14 m·s-1风速的风蚀下，坡面表层（0～1 cm）土壤颗粒粗化.其中，细颗粒（〈0.01 mm）减小9.8%～10.8%，粗颗粒（〉0.05 mm）增加16.8%～20.8%.风蚀改变了坡面物理性状，进而影响了降雨侵蚀泥沙颗粒变化.相对于未风蚀，风蚀处理的侵蚀泥沙细颗粒增加2.7%～189%，粗颗粒降低3.7%～9.3%.风蚀处理后，在不同雨强、不同降雨历时下，侵蚀泥沙颗粒变化趋势不同.雨强60、80、100 mm·h-1时，侵蚀泥沙颗粒变化较大，而雨强150 mm·h-1、产流〉15 min时，变化趋势减缓.

Wind and water are the two dominant erosion agents that caused soil and water losses in the windwater alternate erosion region on the Loess Plateau. It is meaningful to study the impact of windwater alternate erosion on the characteristics of soil particles for understanding the response of soil quality and environment to erosion. Through wind tunnel combined rainfall simulation, this paper studied the characteristics of the erosive sediment particles under the effect of wind-water alternate erosion. The results showed that the particles of 0-1 cm soil were coarsened by wind erosion at the wind speeds of 11 and 14 m·s-1 compared with no wind erosion. Soil fine particles （〈0.01 mm） decreased by 9.8%-10.8%, and coarse particles （〉0.05 mm） increased by 16.8%-20.8%. The physical property of surface soil was changed by the wind erosion, which, in turn, caused an increase in finer particles content in the sediment. Compared with no wind erosion, fine particles （〈0.01 mm） in sediment under the waterwind alternate erosion increased by 2.7%-18.9%, and coarse particles （〉0.05 mm） decreased by 3.7%-9.3%. However, the changing trend of erosive sediment particles after the wind erosion at wind speeds of 11 and 14 m·s-1 was different along with the rainfall intensity and duration. The erosive sediment particles at the rainfall intensities of 60, 80, 100 mm·h-1 changed to greater extents than at the 150 mm·h-1 rainfall intensity with longer than 15 min runoff flowing.