秸秆覆盖对三峡库区坡面侵蚀的影响

目的]分析农作物秸秆不同覆盖处理对坡面产流、产沙影响,为三峡库区坡耕地水土保持措施优化提供技术支持。方法]利用人工模拟降雨技术,分析了5种不同雨强下不同秸秆覆盖处理的径流、泥沙过程。结果]坡面覆盖秸秆能推迟坡面初始产流。在小雨强时,秸秆覆盖推迟初始产流显著,但随着雨强的增加,推迟初始产流的作用降低。在坡面下坡段覆盖秸秆推迟初始产流效果优于在坡面上坡段覆盖秸秆。对于产流产沙而言,在坡面上坡段覆盖秸秆与无覆盖差异不显著,但在坡面下坡段覆盖秸秆时径流模数和侵蚀模数为无覆盖的61.57%~69.1%和14.54%~18.31%,且减少地表径流和泥沙流失效果优于在坡面上坡段覆盖。秸秆覆盖后土壤流失比(SLR)介于0.022~0.611之间,且随着覆盖率的增加而降低,在坡面下坡段覆盖秸秆SLR值在上坡段的1/4。结论]合理选择农作物秸秆在坡面覆盖的坡位及覆盖度,能有效降低坡面产流与侵蚀产沙,产生较好的水土保持效应。

Effects of Mulch Cover on Slope Erosion in Three Gorges Reservoir Area

Objective] The objective of this study is to analyze the effects of different straw mulching treatments on slope runoff and sediment yield in order to provide technical support for soil and water conservation measures in sloping land. Methods] Simulated rainfall was conducted to assess the effects of straw mulching on slope runoff and sediment yield under different rainfall intensity. Results] Straw mulch could delay the initial runoff-yielding time, especially under lower rainfall intensity. As the rainfall intensity increased, the differences among all treatments decreased. The initial runoff-yielding time in the lower slope was longer than that in the upper slope. The mean runoff modulus and erosion modulus in the lower slope accounts for 61.57%~69.1% and 14.54%~18.31% of that in the bare land, respectively. The soil loss ratio(SLR) value ranged from 0.022 to 0.611, and in lower slope it accounted for 25% of that in the upper slope. The soil loss ratio decreased with the increase of straw mulching coverage. Conclusion] Choosing the optimal straw mulching position and coverage can effectively reduce surface runoff and sediment yield, and it is of great importance for soil and water conservation in the Three Gorges reservoir area.