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坡面细沟、浅沟及切沟侵蚀是黄土高原土壤侵蚀的常见类型.为了研究坡度和流量对侵蚀沟沟岸扩张的影响,获得侵蚀沟道断面宽度随时间和空间的动态变化过程,从而预测侵蚀沟道最大宽度,设计了3个试验坡度:12°、20°、30°,3个试验流量:12、20、30L/min,进行了9个坡度流量组合的径流冲刷试验,结合高清摄像监测的方式,记录冲刷过程中沟道侵蚀量、沟道扩张过程.在Matlab中,利用图像自动边缘检测算法提取沟边沿并转换为矢量文件,得到从沟头到沟尾,间隔50mm、每min的沟道断面宽度数据,通过Matlab编程计算,得到了在断面最大沟宽位置处,沟宽随时间变化曲线,从而建立了沟宽随时间变化方程,得到最大沟道宽度及不同时刻的沟道宽度,该方程形式简单,容易求解;沟宽随时间变化曲线符合S型曲线的发展规律,对应着沟岸扩张发生-快速发育-稳定-崩塌-再稳定的周期性过程,沟岸扩张过程中,随着跌坎发育为侵蚀沟,断面侵蚀沟宽度随冲刷时间的变化存在激增点,当沟宽随时间推移趋于无穷时,宽度趋于定值;侵蚀沟沟道发展的最大宽度也可用流量Q和坡度S表示,建立了沟宽最大宽度预测方程(R~2=0.91,RMSE=0.0338);最后,结合断面侵蚀沟宽度的变化曲线,分析了侵蚀过程中坡面沟道侵蚀量与断面沟宽变化的关系,结果表明:流量和坡度是侵蚀过程的动力因素,沟道断面最大宽度与坡度及流量有关.
In order to study the influence of slope and flow rate on the bank expansion of the erosion ditch, the dynamic change of the width of the erosion ditch cross-section with time and space is obtained, so that the erosion of shallow groove, ditch and gully is the common type of soil erosion on the Loess Plateau. In order to predict the maximum width of the erosion channel, three test slopes were designed: 12 °, 20 °, 30 °, three test flow rates: 12,20,30L / min, runoff scouring tests with nine slope flow combinations were carried out, In this paper, the image edge detection algorithm is used to extract the edge of the groove and convert it into a vector file, which is obtained from the groove head to the tail of the groove, separated by 50mm, each min channel width data, and Matlab programming to calculate the maximum width of the cross-section area, the groove width with time curve, so as to establish the groove width with time variation equation, the maximum channel width and groove at different times The width of the channel is simple and easy to solve. The curve of groove width with time conforms to the law of S-curve, corresponding to the periodic process of ditch bank expansion, rapid development, stable-collapse and re-stabilization In the ditch bank expansion process, with the development of the ecliptic ridge to the eroded ditch, there is a sharp increase in the width of the eroded channel along with the erosion time. When the ditch width tends to infinity over time, the width tends to be fixed. The maximum width of the development can also be expressed by the flow rate Q and the slope S, and the maximum width width prediction equation (R ~ 2 = 0.91, RMSE = 0.0338) is established. Finally, the variation curve of the width of the erosion channel is analyzed, The results show that the flow rate and slope are the dynamic factors of the erosion process. The maximum width of the channel section is related to the slope and the flow rate.