| 黄土坡面细沟沟头溯源侵蚀的量化研究 |
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| 引用本文： | 覃超,何超,郑粉莉,韩林峰,曾创烁.黄土坡面细沟沟头溯源侵蚀的量化研究[J].农业工程学报,2018,34(6):160-167. |
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| 作者姓名： | 覃超 何超 郑粉莉 韩林峰 曾创烁 |
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| 作者单位： | 1.西北农林科技大学水土保持研究所高原土壤侵蚀与旱地农业国家重点实验室，杨凌 712100； 2. 水利部黄土高原水土流失过程与控制重点实验室，郑州 450003； 3. 美国密西西比大学国家水科学计算与工程中心，牛津 38677；,1.西北农林科技大学水土保持研究所高原土壤侵蚀与旱地农业国家重点实验室，杨凌 712100； 2. 水利部黄土高原水土流失过程与控制重点实验室，郑州 450003；,1.西北农林科技大学水土保持研究所高原土壤侵蚀与旱地农业国家重点实验室，杨凌 712100； 2. 水利部黄土高原水土流失过程与控制重点实验室，郑州 450003；,4.重庆交通大学河海学院，重庆400074；,5.美国密西西比大学工程学院，牛津 38677 |
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| 基金项目： | 中国科学院国际合作局对外合作重点项目资助（161461KYSB20170013）；国家自然科学基金资助项目（41761144060）；水利部黄土高原水土流失过程与控制重点实验室开放课题基金项目（2017001）；国家留学基金委公派高水平研究生项目 |
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| 摘 要： | 沟头溯源侵蚀占坡面细沟侵蚀量的60%以上。该文运用立体摄影测量技术和人工模拟径流冲刷的方法,研究不同流量和坡度下沟头溯源侵蚀过程及其产沙特征,探讨沟头下切造成的地表形态变化对坡面产沙的影响。结果表明:1)坡面产沙率和沟头溯源侵蚀速率随流量和坡度的增加而增大。流量每增加1 L/min,产沙率增加0.59~5.34倍;坡度从15°增加到20°,产沙率增加14.0%~89.7%。2)当流量小于或等于2 L/min时,产沙率在试验初期增加较快,而后缓慢上升;当流量大于2 L/min时,产沙率始终保持快速上升趋势,沟头溯源长度达到100 cm所需时间较流量为1 L/min时缩短12 min以上。3)坡度对沟头溯源侵蚀速率的影响随流量的增加逐渐减弱。4)细沟长度随时间的变化受流量和坡度的影响,其值可由线性增函数表达;产沙率受沟头溯源侵蚀速率、沟头跌坎高度和沟头下方沟槽内发育的二级沟头数影响,其值可由多元非线性回归方程表示。研究结果可为沟头溯源侵蚀预报模型建立和坡面水土保持措施布设提供理论依据。
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| 关 键 词： | 土壤 径流 侵蚀 细沟 黄土高原 立体摄影测量 溯源侵蚀 二级沟头 |
| 收稿时间： | 2017/10/26 0:00:00 |
| 修稿时间： | 2018/1/25 0:00:00 |
Quantitative research of rill head advancing process on loessial hillslope |
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| Qin Chao,He Chao,Zheng Fenli,Han Linfeng and Zeng Chuangshuo.Quantitative research of rill head advancing process on loessial hillslope[J].Transactions of the Chinese Society of Agricultural Engineering,2018,34(6):160-167. |
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| Authors: | Qin Chao He Chao Zheng Fenli Han Linfeng and Zeng Chuangshuo |
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| Institution: | 1.State Key Laboratory of Soil Erosion and Dryland Farming on Loessial Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China; 2. MWR Key Laboratory of Soil and Water Loss Process and Control in the Loess Plateau, Zhengzhou 450003, China; 3.National Center for Computational Hydroscience and Engineering, University of Mississippi, Oxford 38677, USA;,1.State Key Laboratory of Soil Erosion and Dryland Farming on Loessial Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China; 2. MWR Key Laboratory of Soil and Water Loss Process and Control in the Loess Plateau, Zhengzhou 450003, China;,1.State Key Laboratory of Soil Erosion and Dryland Farming on Loessial Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China; 2. MWR Key Laboratory of Soil and Water Loss Process and Control in the Loess Plateau, Zhengzhou 450003, China;,4.School of River & Ocean Engineering, Chongqing JiaoTong Univerisity, Chongqing 400074, China; and 5.School of Engineering, University of Mississippi, Oxford 38677, USA |
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| Abstract: | Abstract: Headcut erosion constitutes more than 60% of hillslope soil loss. Quantitative research on rill headcut erosion processes provides fundamental information for process-based erosion modeling. Due to the complicated headcut morphologies and flow regimes near a headcut, it is hard to accurately predict the erosion rate of a headcut in some soil erosion prediction models. Current knowledge on the impacts of headcut height, headcut advancing rate and secondary headcuts developed on well-formed rill channel on soil loss is limited. Thus, simulation experiments with pre-made initial headcuts (5 cm high) were designed to investigate the effects of inflow rate, slope gradient, headcut height and headcut number on rill head advancing process. Soil boxes (2.0 m long, 0.3 m wide and 0.5 m deep) with 2 slope gradients (15° and 20°) and 4 inflow rates (1.0, 2.0, 3.0 and 4.0 L/min) were subjected to upland concentrated flow. At slope lengths of 70 and 120 cm, 2 cameras were mounted 1.5 m over the soil box and were controlled by an infrared remote control to photograph simultaneously. High precision DEMs (digital elevation models) obtained by photogrammetry were used to detect changes of hillslope morphology and headcut advancing process. The results showed that sediment delivery and headcut advancing rate increased while initial headcut height and secondary headcut number did not strictly increase with the increase of inflow rate and slope gradient. Sediment delivery increased by 0.59-5.34 times and 14.0%-89.7% when inflow rate increased by 1 L/min and slope gradient increased from 15° to 20°, respectively. When inflow rate was equal to or smaller than 2 L/min, sediment delivery increased fast at the beginning and kept stable later. When inflow rate was greater than 2 L/min, sediment delivery kept increasing during the whole experiment. So, 2 L/min was a threshold of inflow rate that may cause rill head advancing rate to increase significantly. Compared to the treatments at 1 L/min inflow rate, the duration for a headcut retreating by a certain length (100 cm) was shortened by more than 12 min when inflow rate was greater than 2 L/min. The effects of slope gradient on rill head advancing decreased with the increase of inflow rate. Linear equation which included unit flow rate and slope gradient was used to predict the rill length time series. Relative errors between predicted values and observed values were smaller than 16% and both the R2 and the Nash coefficient values were greater than 0.95. Soil loss on the hillslope dominated by rill head advance was determined by headcut advancing rate, headcut height and the number of secondary headcuts developed below the initial headcut. Soil loss increased with the increase of headcut advancing rate or headcut height in a power function while showed a linear correlation with the number of secondary headcuts. Soil loss can be modeled with a non-linear regression equation with a determination coefficient of 0.932. Results of this study provide new knowledge on rill headcut modeling. It is recommended that upslope runoff should be intercepted and concentrated rill flow velocity should be reduced when soil and water conservation practices are designed on steep loessial hillslope. |
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| Keywords: | soils runoff erosion rill Loess Plateau photogrammetry headcut advance secondary headcut |
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