目的研究不同耕作措施和降雨强度下地表高程和糙度的空间分布特征以及降雨前后二者的变化,以探讨不同耕作措施和降雨强度对坡耕地地表糙度的影响。方法人工降雨条件下,模拟人工锄耕、人工掏挖、等高耕作3种耕作措施和对照组直型坡,测量、计算并分析了各坡面高程信息和地表糙度的空间分布特征以及降雨前后二者的变化。结果降雨前坡面的高程空间分布在不同耕作措施之间具有显著性差异。直型坡高程的统计方差最小,高程分布最集中;与直型坡相比,等高耕作坡面高程的统计方差最大,高程分布最离散;其次是人工掏挖和人工锄耕坡面。雨前地表糙度大小为等高耕作>人工掏挖>人工锄耕>直型坡。降雨能显著改变地表糙度值的大小,并呈现同一耕作措施随雨强增大地表糙度值改变越多的规律。降雨后等高耕作、人工掏挖和人工锄耕这3种措施的地表糙度均呈减小趋势,同一雨强下,等高耕作糙度减小最多,人工掏挖次之,人工锄耕糙度减小最少。直型坡的地表糙度在雨后却有所增加,在60、90和120 mm·h-1雨强下,直型坡雨后糙度分别增加了10.9%、22.5%和36.5%。雨后各措施地表糙度值均改变,但仍为等高耕作>人工掏挖>人工锄耕>直型坡。结论耕作措施是形成坡耕地地表糙度的主要原因,不同的耕作方式造成地表起伏状态的差异,使不同耕作措施下的地表糙度具有空间异质性。降雨作用会减小各耕作坡面的地表糙度,增加对照组的地表糙度,且随降雨强度增大,地表糙度变化越剧烈。耕作措施造成的地表初始糙度越大,降雨对糙度的减小作用越显著。但人工锄耕、人工掏挖和等高耕作3种耕作措施对地表糙度的影响大于降雨对地表糙度的影响。
Objective]The objectives of this paper were to study the spatial distribution characteristics of soil surface elevations and roughness caused by the tillage treatments and to investigate the changes in soil surface elevations and roughness after rainfall, so as to deeply understand the effects of tillage treatments and rainfall intensities on spatial distribution of soil surface elevations and soil surface roughness (SSR).[Method] The experiment was arranged in completely randomized block design, with three replications for each treatment. The size of soil box was 2.0 m in length, 1.0 m in width and 0.5 m in depth. The gradient of soil box was 18%. The tillage treatments used were artificial shallow plowing (ASP), artificial deep plowing (ADP), contour plowing (CP), and no treatment (CK). Three rainfall intensities (60 mm·h-1, 90 mm·h-1 and 120 mm·h-1) were applied to conduct the rainfall, and rainfall duration was 90 minutes. Soil surface elevations in soil box were measured using a laser scanner before and after rainfall to analyze the changes of elevation and SSR.[Result] There was a significant difference in spatial distribution of elevations among these four tillage treatments. Statistical variance of surface elevations of CK was the lowest compared with ASP, ADP and CP,including the spatial distribution of elevation of CK was the highest concentration than the others. While statistical variance of surface elevations of CP was the highest compared with ASP, ADP and CK, suggesting the spatial distribution of surface elevations of CP was the most dispersion one. Spatial distribution of surface elevations of ASP and ADP were the median. Before the rain, the order of SSR value was CP>ADP>ASP>CK. This implied that deep ploughing treatment caused severer changes in SSR than shallow ploughing treatment. SSR value changed apparently after rainfall. And the changes of SSR aggravated as rainfall intensity increased under the same tillage treatment. After rain