The proportion of jet flow and on-wall flow and its effects on soil loss and plunge pool morphology during gully headcut erosion
The proportion of jet flow and on-wall flow and its effects on soil loss and plunge pool morphology during gully headcut erosion
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DOI：
10.1016/j.jhydrol.2021.126220
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发表时间：
2021-03
影响因子：
6.4
通讯作者：
M. Guo;Lou Yibao;Zhuo-xin Chen;Wen-long Wang;Lanqian Feng;Xingyi Zhang
中科院分区：
文献类型：
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作者：
M. Guo;Lou Yibao;Zhuo-xin Chen;Wen-long Wang;Lanqian Feng;Xingyi Zhang
沟头侵蚀是沟道侵蚀的主要过程，也是沟道侵蚀产沙量的主要贡献者。然而，水头开挖引起的射流和壁面水流的比例及其对土壤流失和消落池形态的影响仍不清楚。通过模拟水流冲刷试验，研究了不同流量(q0=73.0~7.2km3h−1)和不同顶墙高度(H0=60.3~1.2m)条件下，射流和壁面流的比例及其对水土流失的贡献，以及壁面流冲刷对消力池形态的影响。计算结果表明，射流流量和壁面流量分别占上游水口总流量的15.7%、22.6%和77.4%、84.3%，−分别为22.6%、77.4%和84.3%。喷流、壁面流及其交互作用分别占总流失量的53.5%、34.9%和11.6%。此外，H0对喷流引起的土壤流失及其与壁面流的相互作用具有较大的影响，但壁面造成的土壤流失主要受q0的控制。消力池的宽度和深度随冲刷时间呈对数增长，Q0和H0对消力池形态的发展有显著影响。壁面流仅在H0为0.3~0.9m时，降低了消落池深度27.8%~71.4%，使消落池宽度减小了24.3%−57.3%，但对H0为1.2 cm，Q0为4.8m3h−1时，消落池宽度增加了7.5%。射流能耗与水池形态的关系最为密切。上游沟首集中流对消力池形态的影响比H0更大。本研究有助于加深对沟道侵蚀机理的认识，为沟道侵蚀防治措施的设计提供科学依据。
Gully headcut erosion is recognized as the primary process of gully erosion and is the main contributor to sediment yield of gully erosion. However, the proportion of jet flow and on-wall flow induced by headcut and its effects on soil loss and plunge pool morphology are still unclear. A simulated flow-scouring experiment was conducted to explore the proportion of jet flow and on-wall flow and their contributions to soil loss and the effect of on-wall flow erosion on plunge pool morphology under different flow discharge (q0= 3.0–7.2 m3h−1) and headwall height (H0= 0.3–1.2 m) conditions. Our results showed that jet flow and on-wall flow accounted 15.7% − 22.6% and 77.4% − 84.3% of total flow volume upstream headcut, respectively. Jet flow, on-wall flow and their interaction contributed 53.5%, 34.9% and 11.6% of total soil loss amount, respectively. Furthermore,H0exhibited greater effect on soil loss caused by jet flow and its interaction with on-wall flow, but the soil loss caused by on-wall was mainly controlled byq0. The width and depth of plunge pool logarithmically increased with scouring time, and theq0andH0significantly affected the development of plunge pool morphology. On-wall flow reduced plunge pool depth by 27.8%–71.4%, and it weakened plunge pool width by 24.3%−57.3% only underH0of 0.3–0.9 m, but forH0of 1.2 m andq0of >4.8 m3h−1, it improved the plunge pool width by 7.5%. The energy consumption of jet flow showed the closest relationship with plunge pool morphology. The concentrated flow upstream gully head exhibited the stronger effect on plunge pool morphology thanH0. This study is helpful to deepen the understanding of gully erosion mechanism and provide scientific reference for the design of gully erosion prevention and control measures.