黒垆土坡面细沟形态演变规律试验研究

Experimental study on morphological evolution of rills on dark loessial soil slope

为探究黒垆土坡面细沟形态变化规律,运用三维激光扫描技术和人工模拟降雨方法,以黑垆土为对象,选取60 mm/h雨强对面积为15 m^2的20°坡面进行历时均为1 h的三场模拟降雨试验,分析了黑垆土坡面细沟发育过程。结果表明:(1)前两次降雨坡面以断续细沟为主,侵蚀方式主要为溯源侵蚀,第二场降雨结束时,细沟累积长度、平均宽度、平均深度分别为38.17 m、0.19 m、0.10 m,坡面细沟总面积占试验土槽面积的19.8%;第3次降雨坡面以连续细沟为主,细沟溯源侵蚀作用减弱,细沟沟壁崩塌和沟底下切增强,细沟累积长度减少5.66%,细沟平均宽度、平均深度、总面积分别增加了26.32%、60%、24.24%。(2)细沟平均宽度、平均深度、等高线偏离度沿斜坡长呈先增后减再增的波动现象,随着降雨场次的增加,细沟形态参数在沿坡长4~6 m处的最大值出现上移。径流能量的消长对坡面细沟形态演变规律具有明显影响。(3)细沟宽度和细沟深度在前两场降雨随距细沟沟头长度的增加呈先增后减趋势,在第三场降雨呈先增后减再增的趋势。细沟深度随细沟宽度的增加而增加,在当细沟深度到达犁底层后,细沟深度增加变缓,细沟宽度增加变快。

In order to investigate the morphological changes of rills on the slope of dark loessial soil. Using three-dimensional laser scanning technology and artificial simulated rainfall method, the black soil was used as the object, and the 60 mm/h rain intensity was selected for the 20° slope with an area of 15 m^2 for three simulated rainfall experiments with a duration of 1 h. The results show:(1) The first two rainfall slopes are dominated by intermittent rills, and the erosion mode is mainly traceable erosion. At the end of the second field, the cumulative length, average width and average depth of the rills were 38.17 m, 0.19 m and 0.10 m, respectively, and the total area of the rills on the slopes accounted for 19.8% of the test soil trough area;The third rainfall slope is dominated by continuous rills. The erosive traceability of the rills is weakened, and the rill wall collapses and the bottom cuts are enhanced. The cumulative length of the fine groove decreased by 5.66%, and the average width, average depth and total area of the fine groove increased by 26.32%, 60% and 24.24%, respectively.(2) The mean width, average depth, and contour deviation of the rill are increased first, then decreased, and then increased along the slope length. With the increase of rainfall events, the rill morphology parameters move up at the maximum along the slope length of 4~6 m. The growth and decline of runoff energy has a significant impact on the morphological evolution of rills on slopes.(3) The width of the rill and the depth of the rill increased first and then decreased with the increase of the length of the gully head in the first two fields. In the third period, the rainfall increased first, then decreased and then increased. The depth of the fine groove increases with the increase of the width of the fine groove. When the depth of the fine groove reaches the bottom of the plow, the depth of the fine groove increases and the width of the fine groove increases rapidly.