室内人工降雨条件下黄土侵蚀坡面的变异特征研究

Variation characteristics of loess erosion hillside under indoor artificial rainfall conditions

基于室内人工降雨试验条件下获取的黄土坡面侵蚀的九期DEM数据,计算出不同演化时期黄土坡面的坡度、坡向及沟道网络,利用等分坡度直方图、等分坡向玫瑰花图和沟道分级网络对坡面侵蚀变异特征进行研究,并初步分析了该变异特征与黄土坡面侵蚀和演化过程之间的关系。结果表明:在黄土坡面侵蚀过程中,该坡面的坡度离散程度在逐步增加后基本保持稳定;其主导坡向总体呈现逐步有序化的变化特征,由多个主导坡向逐步演化为与该坡面主干沟道总体走向基本一致的一个主导坡向;其沟道网络逐步发育成典型树状网络并基本保持稳定,且形成了完整和严密的沟道等级结构。上述侵蚀坡面变异特征在一定程度上反映出该坡面在发育初期侵蚀较为强烈但在后期强度有所减弱。本研究是对黄土侵蚀坡面变异特征的初步探索,对未来进一步揭示黄土坡面的侵蚀机理和演化规律具有重要理论意义。

The erosion mechanism of loess hillside and its landform variation characteristics during erosion need further research.Therefore,based on the nine-phase DEM data of erosion and evolution of a loess hillside obtained from indoor artificial rainfall experiments at Yangling District,Shaanxi Province,China,the slope,aspect and channel networks of the loess hillside in different evolution periods have been calculated.We used the slope histogram,the rose diagram of aspect and the channel networks to study the variation characteristics of erosion process of the loess hillside,and preliminarily analyzed the relationship between the variation characteristics and the erosion and evolution process of the loess hillside.The results show that the slope dispersion degree of the loess hillside is basically stable after gradually increasing during the erosion process;The dominant aspects of the loess hillside show a gradual orderly change and gradually evolve from a plurality of dominant aspects to a dominant aspect that is basically consistent with the overall orientation of the main channel of the loess hillside.The channel network gradually develops into a typical tree network,and remains basically stable and forms a complete and strict channel hierarchy.The above-mentioned variation characteristics of the loess hillside reflect that the hillside is eroded strongly during its prophase but weakened during its activity stage.This study is a preliminary exploration of the variation characteristics of loess erosion hillside,and it has important theoretical significance for further revealing the erosion mechanism and evolution law of loess hillside.