黄土丘陵区堆积体边坡对上方来水的侵蚀响应

Downslope erosion response of engineered landform to upslope runoff in loess hilly region

  • 摘要: 为探明上方来水类型对工程堆积体高陡边坡下部冲刷侵蚀的定量影响,以神府高速公路沿线典型工程堆积体陡坡坡面(36°)为例,设计4种上方来水类型,通过野外放水冲刷试验分析了不同上方来水类型下堆积体坡面的径流侵蚀输沙过程.结果表明:①上方来水类型对堆积体坡面下部的产流影响较小,却干扰了坡面侵蚀产沙过程,造成土壤流失量增加;②径流深、单宽径流侵蚀力和水流功率均可以较好地预测堆积体边坡下部输沙模数的变化;③单宽径流侵蚀功率可以作为表征坡面尺度次径流事件中径流侵蚀力变化的指标.研究结果可为工程堆积体土壤侵蚀强度评价、侵蚀模型建立及新增水土流失防治提供参考.

     

    Abstract: In order to figure out the quantitative influence on wash-scour erosion at the bottom of high and steep slope of engineered landform caused by upslope runoff, the typical abrupt slope (36°) of engineering deposits along the expressway from Shenmu to Fugu was selected in the research to conduct a set of field runoff scouring experiments. Given that total runoff amount was kept constant, four types of upslope runoff were designed to conduct the subsequent analysis of the downslope runoff erosion response and sediment transport process on the abandoned spoil-deposit. The results indicated that: ① The type of upslope runoff had little influence on total surface runoff production at the bottom of the deposit slope, but it interfered the process of slope erosion and sediment yield, which increased the amount of soil loss; ② All the indicators of runoff depth, unit runoff erosivity, and stream power can well predict the intra-event sediment delivery modulus at the bottom of deposits slope induced by individual variable upslope runoff events; ③ The unit runoff erosivity based on flow discharge per unit width and runoff depth, can be used as the index to represent the change of runoff erosion power in single upslope runoff events, regardless of the type of upslope runoff. The results can be helpful in evaluating the intensity and degree of soil erosion, establishing erosion model in dramatically disturbed areas, and preventing from newly-arising water and soil losses against engineered landforms.

     

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