不同土壤坡面细沟侵蚀差异与其影响因素

采用室内纯净水人工模拟降雨试验,在坡度为10°、15°、20°、25°坡面,土槽为5 m、10 m两种规格,对两种土壤((土娄)土与黄绵土)分别进行雨强为1.5 mm min-1,的降雨实验,利用三维激光扫描仪对每一场降雨后的坡面进行监测,分析不同坡度对细沟侵蚀的影响,比较两种土壤坡面细沟侵蚀的差异,以及其差异的影响因子.结果表明:(土娄)土土壤颗粒以粉粒与黏粒为主,粉粒占总质量的64.12％,黏粒为28.42％.黄绵土的土壤颗粒以粉粒为主占总质量的67.95％,黏粒与沙粒含量较少,黏粒占14.52％,沙粒占17.53％.在相同条件下,(土娄)土降雨过程中人渗缓慢,产流时间、坡面流速均快于黄绵土,跌坎出现时间也较早,使其更容易产生细沟.(土娄)土的径流量高于黄绵土,在降雨过程中,径流稳定时间较早.(土娄)土侵蚀量高于黄绵土,(土娄)土产沙率呈增加趋势,黄绵土含沙量变化不明显.从坡面细沟发育来看,(土娄)土坡面细沟成平行状分布,黄绵土细沟为较宽树枝状.

Rill erosion on different soil slopes and their affecting factors

Indoor simulation of rainfall, 1.5 mm min^-1 in intensity was conducted using deionized water on slopes of Lou soil and Cultivated loessial soil, 10°, 15°, 20° and 25° in slope degree, and 5 m and 10 m in shope length,separately. Changes in the slopes caused by each rainfall event were monitored with a 3D laser scanner and analyzed for impact of slope degree on rill erosion, differences between slopes of different soils in rill erosion and their affecting factors. Results show that as the Lou soil is dominated with silt and clay in texture with silt content being 64.12% and clay content 18.42, and the Cultivated loessial soil composed mainly with silt (67.95%) and some clay (14.52%) and sand (17.53%), under the same conditions, rian water infiltration rate was lower, runoff generation earlier and runoff velocity higher in the former than in the latter, and as a result, erosion holes occurred earlier and rills formed more easily in the former. During the rainfall event, higher in volume, the runoff stabilized earlier in the former than in the latter. As the erosion rate was higher in the former, silt yield tended to increase, while it remained almost unchanged in the latter. Comparison between the slopes of two different soils in rill development shows that the rills on the Lou soil slopes were distributed in parallel, while those on of the Cultivated loessial soil slopes looked like wide tree branches.