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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >The role of soil pipe and pipeflow in headcut migration processes in loessic soils
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The role of soil pipe and pipeflow in headcut migration processes in loessic soils

机译：土壤管道和管道在黄土泥土头部迁移过程中的作用

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Headcut formation and migration was sometimes mistaken as the result of overland flow, without realizing that the headcut was formed and being influenced by flow through soil pipes into the headcut. To determine the effects of the soil pipe and flow through a soil pipe on headcut migration in loessic soils, laboratory experiments were conducted under free drainage conditions and conditions of a perched water table. Soil beds with a 3-cm deep initial headcut were formed in a flume with a 1.5-cm diameter soil pipe 15 cm below the bed surface. Overland flow and flow into the soil pipe was applied at a constant rate of 68 and 1 l min(-1)at the upper end of the flume. The headcut migration rate and sediment concentrations in both surface (channel) and subsurface (soil pipe) flows were measured with time. The typical response was the formation of a headcut that extended in depth until an equilibrium scour hole was established, at which time the headcut migrated upslope. Pipeflow caused erosion inside the soil pipe at the same time that runoff was causing a scour hole to deepen and migrate. When the headcut extended to the depth of the soil pipe, surface runoff entering the scour hole interacted with flow from the soil pipe also entering the scour hole. This interaction dramatically altered the headcut processes and greatly accelerated the headcut migration rates and sediment concentrations. Conditions in which a perched water table provided seepage into the soil pipe, in addition to pipeflow, increased the sediment concentration by 42% and the headcut migration rate by 47% compared with pipeflow under free drainage conditions. The time that overland flow converged with subsurface flow was advanced under seepage conditions by 2.3 and 5.0 min compared with free drainage conditions. This study confirmed that pipeflow dramatically accelerates headcut migration, especially under conditions of shallow perched water tables, and highlights the importance of understanding these processes in headcut migration processes. (c) 2020 John Wiley & Sons, Ltd.
机译：由于陆上流动的结果，头寸地层和迁移有时被误认为，不认识到头寸形成并受到通过土壤管进入头部的流量的影响。为了确定土壤管道和流过土壤管道的效果，在黄土地区的头部迁移中，在自由排水条件和栖息的水位的条件下进行实验室实验。用3厘米深的初始头部的土壤床形成在床表面下方1.5厘米直径的土壤管15厘米的水槽中。陆上流动和流入土壤管的恒定速率在水槽的上端以68和1 L min（-1）的恒定速率施加。用时间测量表面（通道）和地下（土管）流动的头部迁移率和沉积物浓度。典型的响应是形成深度的头部，直到建立平衡冲击孔，此时头部迁移上升。 Pipeflow在径流导致防水孔加深和迁移的同时在土水管内引起侵蚀。当头部延伸到土管的深度时，表面径流进入冲泡孔与来自土管的流量相互作用，也进入冲击孔。这种相互作用显着改变了头脑过程，大大加速了头部迁移率和沉积物浓度。除潮管道外，栖息地提供进入土管的栖息地水位的条件，与游离排水条件下的管道流量相比，将沉积物浓度增加42％，并将头部迁移率降低47％。与自由排水条件相比，在渗流条件下，泄漏条件下泄漏的陆涌流量的陆路流动的时间提出。本研究证实，Pipeflow显着加速了头部迁移，特别是在浅栖息的水表条件下，强调了了解在头部迁移过程中了解这些过程的重要性。 （c）2020 John Wiley＆Sons，Ltd。

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