Experimental Observations of Bedload Tracer Movement: Effects of Mixed Particle Sizes and Bedforms
Experimental Observations of Bedload Tracer Movement: Effects of Mixed Particle Sizes and Bedforms
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DOI：
10.1029/2022wr033114
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发表时间：
2023-05
影响因子：
5.4
通讯作者：
Ashutosh Kumar Singh;Zi Wu;P. Wilcock;E. Foufoula‐Georgiou
中科院分区：
文献类型：
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作者：
Ashutosh Kumar Singh;Zi Wu;P. Wilcock;E. Foufoula‐Georgiou
预测床头液颗粒的运输是一个明显的理论和实际兴趣，在存在床形的情况下，很少有在河流中运输的问题，这可能会捕获谷物，从而在一系列的床单中，在大型实验，床位的旅行范围内，在一系列砂浆中会影响一系列的流行距离。床形降低了所有示踪剂和流动条件的床形钢，床形成示踪剂的主要控制，床形捕获量与底壁高度的比率增加了，而植物粒度的比例为50％的捕获效率，以占用两次和90％的诱捕效率。旅行所有示踪剂大小和放电的距离，在相对较小的时间尺度上提供了示踪剂传输理论和床形捕获的第一个连接，并表明示踪剂的正常扩散。重型尾巴特征。
Predicting the transport of bedload tracer particles is a problem of significant theoretical and practical interest. Yet, little understanding exists for transport in rivers in the presence of bedforms, which may trap grains and thereby influence travel distance. In a series of flume experiments with a sandy gravel bed in a large experimental flume, bed elevation and tracer travel distances were measured at high resolution for a range of discharges. As discharge increased, bedform height increased and bedform length decreased, increasing bedform steepness. For all tracer sizes and flow conditions, bedforms act as primary controls on the tracer travel distances. Bedform trapping increases linearly with the ratio of bedform height to tracer grain size, with 50% trapping efficiency for a ratio of two and 90% trapping efficiency for a ratio of four. A theoretical model based on the extended active layer formulation for sediment transport is able to capture much of the distribution of measured travel distances for all tracer sizes and discharges, providing a first connection between tracer transport theory and bedform trapping and indicating normal diffusion of tracers at relatively small timescales. Variable bedform geometry can influence trap efficiency for individual bedforms and the theoretical model can help identify “preferential trapping” conditions. The distribution of tracer travel distances for a mixture of grain sizes and variable discharge, as expected in natural rivers, displays heavy tail characteristics.