模拟降雨条件下地表糙度动态变化特征研究

地表糙度是影响土壤侵蚀的因素之一。为进一步明确地表糙度的侵蚀效应,通过野外模拟降雨试验,研究了地表糙度在降雨前后、不同坡度、不同植被覆盖度、不同空间坡段的动态变化特征,探讨了地表糙度变化规律及其影响因素。结果表明:在降雨过程中,土地利用类型、雨强、降雨顺序、坡度和植被覆盖度都会对糙度产生影响。随着降雨场次的增加,地表糙度逐渐增大;在试验范围内,坡度越大,地表糙度增加幅度越大,增加趋势越明显;植被覆盖度越大,地表糙度变化越小。坡面的各个坡段变化情况整体遵循上述规律,但在某些坡段内出现空间变异性,导致有些坡段可以拦蓄径流泥沙,消减侵蚀,而有些坡段可以增加潜在的冲刷,加剧侵蚀;多个因子以及因子间的交互效应成为影响糙度变化的主要因素。研究结果为揭示地表糙度的侵蚀特征提供了一定的理论依据,同时也为黄土高原水土流失治理奠定理论基础。

Study on Dynamical Variation Characteristics of Surface Roughness under Field Simulated Rainfall Condition

Soil surface roughness is one of the main factors affecting soi1 erosion.To further determine effects of soil surface roughness on the erosion,dynamical variation characteristics of surface roughness,variation regularity and affecting factors were obtained under following conditions,i.e.rainfall sequence,slope,vegetation coverage and spatial slope section through field simulated rainfall experiment.Results showed that surface roughness was always affected by the above factors during rainfall period.Soil surface roughness increased with rainfall events.The richer the vegetation coverage was,the less the surface roughness was.The steeper the slope was,the more increase extent of surface roughness was,and the more obvious of increase tendency was in experimental range.The variation rules of each slope section were overall following the above patterns,but there was spatial variability in some slope sections.Due to the spatial variability,some slope section′s function was water storage and sediment reduction as well as erosion reduction.On the contrary,the effect on sediment and runoff was potential flushing and erosion aggravation in other slope section.The factors and interaction effect were the main affecting factors on variation of surface roughness.The results provide theoretic basis for revealing the erosion characteristics through soil surface roughness,and at the same time,it can serve for controlling soil and water loss on the Loess Plateau.