黄土耕作坡面溅蚀过程中微地形响应特征

Variation Characteristics of Micro-topography in Tillage Loess Slope During Splash Erosion

[目的]探究60mm/h雨强下不同耕作坡面在溅蚀阶段的微地形变化特征,为黄土坡地水土保持耕作方式布设提供科学依据。[方法]在室内人工模拟降雨试验的基础上,采用激光扫描量测方法分别获取溅蚀前后4种不同耕作方式（人工锄耕、人工掏挖、等高耕作、耙磨整平）黄土坡面微地形相对高程,并对能反映微地形变化的高精度M-ΔDEM进行了分析。[结果]不同耕作措施下坡面微地形均具有较弱的空间变异,其空间分异主要受耕作措施的影响;降雨对微地形具有一定的夷平效应,且不同耕作坡面在1~1.3m尺度范围内均表现出侵蚀平衡现象;不同耕作微地形对溅蚀均具有阻滞作用,其中人工掏挖和等高耕作具有较强的水土保持作用。[结论]微地形水系分维能较好地反映复杂的微地形特征,而坡面耕作方式是溅蚀过程中微地形时空变异分布状况的控制性因子。

[Objective]The aim of this study is to explore the variation characteristics of the micro-topography during the splash erosion under the rainfall intensity of 60mm/h in order to provide the scientific basis for layout of the soil and water conservation farming pattern in loess slope land.[Methods]Four common tillage treatments（artificial backhoe,artificial digging,contour tillage and rake wear leveling）were prepared in the loess region.Artificial rainfall,laser scanning and GIS technology were adopted to generate high precision M-ΔDEM which can reflect the real variation of tillage slopes.[Results]Different tillage slopes showed low spatial variability,and its spatial pattern was mainly affected by tillage measures rather than rainfall.The rainfall in splash erosion had a general flattening effect on the micro-topography,and different tillage slopes showed an erosion balance within the scale of 1~1.3m.Micro-topography has strong retarding effect on the splash erosion.The artificial digging and contouring tillage had a better soil and water conservation effect.[Conclusion]Micro-topographic stream with its fractal dimension can well reflect the complex characteristic of micro-topographic,and tillage treatments control the spatial and temporal variation of micro-topographic during splash erosion process.