次降雨下砒砂岩坡面细沟形态发育及其对侵蚀产沙的影响

Development of Rill Morphology on Sandstone Slopes Under Individual Rainfall Event and Its Effect on Erosion and Sediment Production

[目的]以水蚀剧烈的砒砂岩区裸露坡面为研究对象,分析次降雨下坡面细沟形态演变及侵蚀产沙特征,以期为坡面沟蚀发育演变及坡面水土流失治理提供理论依据。[方法]基于野外径流小区原位监测试验,采用三维激光扫描仪监测径流小区两个雨季13次自然降雨下细沟发育过程及产流产沙规律。[结果](1)小区内细沟发育过程分为4个阶段:跌坎发育—断续细沟—连续细沟—沟网形成;(2)细沟长度、宽度、深度及细沟体积、细沟密度、细沟复杂度均随着降雨的继续呈上升趋势,而细沟宽深比呈下降趋势;(3)研究区内中雨对细沟发育贡献最大,其发生频率为53.69%,对细沟形态的影响占比71.25%。[结论]细沟形态变化对产沙的影响较大,细沟出现后产沙量明显上升,产沙量与细沟发育过程对应关系较好,而对产流过程的影响有限,尤其细沟体积与产沙量及含沙量的相关性最强。

[Objective]The exposed slope was selected to reveal the evolution of the pattern of rill and the characteristics of erosion-induced sediment generation on the slope,in order to provide theoretical basis for the development of slope terrain and soil erosion management.[Methods]Rill development and runoff and sediment production under 13 natural rainfall events in two rainy seasons were analyzed based on in situ detection conducted by using the three-dimensional laser scanner under the natural rainfall conditions in the field.[Results](1)Rill development can be divided into four stages:drop ridge development-intermittent rill-continuous rill-furrow network formation(2)The length,width,depth and volume of rill,density of fine rills,and complexity of rills all show the increasing trend with the continuation of rainfall,while the ratio of width to depth of rill shows the decreasing trend.(3)The largest contribution to its development is the medium rainfall with the frequency of 53.69%,and the effect of medium rainfall on rill morphology accounts for 71.25%.[Conclusion]The change of rill morphology has a greater impact on sediment production,and sediment production increases significantly after the appearance of rills,and sediment production corresponds well with the development process of rills,while the impact on the runoff production process is limited.In particular,the correlation between rill volume and sediment production and sediment content is the strongest.