Bedload tracing in a high‐sediment‐load mountain stream
Bedload tracing in a high‐sediment‐load mountain stream
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高含沙量山间溪流的床载追踪
DOI：
10.1002/esp.2245
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发表时间：
2012
影响因子：
3.3
通讯作者：
M. Deschatres
中科院分区：
文献类型：
--
作者：
F. Liébault;H. Bellot;M. Chapuis;S. Klotz;M. Deschatres
本文报道了一项射频识别（RFID）追踪实验，该实验在典型的高山砾石床激流的高含沙量山溪中实施。研究地点是Bouinenc激流，这是法国东南部blsamoone河的一条支流，流经38.9平方公里的退化集水区。2008年春季，我们部署了451种示踪剂，b轴长度从23毫米到520毫米不等。示踪剂沿8个横截面播种，这些横截面位于河流最低2·3公里的上游部分。在2008年、2009年和2010年7月进行了三次示踪剂清查。移动示踪剂的回收率从2008年的78%下降到2009年的45%和2010年的25%。对示踪剂位移的观察显示，沉积物弥散度非常高，领跑者在部署后仅三个月就走了2公里多。随着时间的推移，采收率的下降被解释为快速分散而不是深埋的结果。我们估计，在跟踪实验开始后的三年内，在活跃通道中部署的64%的示踪剂是从2.3公里的研究中输出的。旅行距离的特征是右偏和重尾分布，由幂律函数正确拟合。这支持了这样一种观点，即在泥沙供应相对于输沙能力丰富的砾石河床中，河床输沙可被视为一种超扩散的泥沙分散过程。研究还表明，与部署在砾石坝中的示踪剂相比，最初部署在低流量通道中的示踪剂的迁移率提高了15 - 30倍。版权所有©2011 John Wiley & Sons， Ltd
This paper reports a radiofrequency identification (RFID) tracing experiment implemented in a high‐sediment‐load mountain stream typical of alpine gravel‐bed torrents. The study site is the Bouinenc Torrent, a tributary to the Bléone River in southeast France that drains a 38·9‐km² degraded catchment. In spring 2008, we deployed 451 tracers with b‐axis ranging from 23 to 520 mm. Tracers were seeded along eight cross‐sections located in the upstream part of the lowest 2·3 km of the stream. Three tracer inventories were implemented in July 2008, 2009 and 2010. Recovery rates calculated for mobile tracers declined from 78% in 2008 to 45% in 2009 and 25% in 2010. Observations of tracer displacement revealed very high sediment dispersion, with frontrunners having travelled more than 2 km only three months after their deployment. The declining recovery rate over time was interpreted as resulting from rapid dispersion rather than deep burial. We evaluated that 64% of the tracers deployed in the active channel were exported from the 2·3‐km study reach three years after the onset of the tracing experiment. Travel distances were characterized by right‐skewed and heavy‐tailed distributions, correctly fitted by a power‐law function. This supports the idea that in gravel‐bed rivers with abundant sediment supply relative to transport capacity, bedload transport can be viewed as a superdiffusive sediment dispersion process. It is also shown that tracers initially deployed in the low‐flow channel were characterized by a 15‐ to 30‐fold increase of mobility compared to tracers deployed in gravel bars. Copyright © 2011 John Wiley & Sons, Ltd.