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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >A flume experiment on wood storage and remobilization in braided river systems
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A flume experiment on wood storage and remobilization in braided river systems

机译：辫状河流系统中木材储存和迁移的水槽实验

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摘要

This work investigates wood dynamics in braided streams through physical modelling in a mobile bed laboratory flume, with the specific objective to characterize wood storage and turnover as a function of wood input rate and of wood element type. Three parallel channels (1.7m wide, 10m long) filled with uniform sand were used to reproduce braided networks with constant water discharge and sediment feeding. Wood dowels with and without simplified root wads were regularly added at the upstream end of each flume at different input rates, with a 1:2:3 ratio between the three flumes. Temporal evolution of wood deposition patterns and remobilization rates were monitored by a series of vertical images that permitted the recognition of individual logs. Results show that wood tends to disperse in generally small accumulations (< 5 logs), with higher spatial density on top of sediment bars, and is frequently remobilized due to the intense morphological changes. The amount of wood stored in the channel depends on log input rate through a non-linear relationship, and input rates exceeding approximately 100 logs/hour determine a sharp change in wood dynamics, with higher storage volume and augmented formation of large jams (> 10 elements) that are less prone to remobilization. Presence of root wads seems to play a minor role in wood deposition, but it reduces the average travel distance of logs. Turnover rates of logs were similar in the three flumes, independently of wood input rate and largely resembling the turnover rate of exposed bars. For the simulated conditions, significant effects of wood on bed morphology were not observed, suggesting that interactions with fine sediments and living vegetation are crucial to form large, stable wood jams able to bring about relevant morphological changes. Copyright ? 2014 John Wiley & Sons, Ltd.
机译：这项工作通过在移动床实验室水槽中进行物理建模来研究编织流中的木材动力学，其特定目的是根据木材输入速率和木材元素类型来表征木材的储存和周转。使用填充有均匀沙子的三个平行通道（宽1.7m，长10m）来再现具有恒定排水量和沉积物供给量的编织网。定期在每个水槽的上游端以不同的输入速率添加带有和不带有简化根部嵌条的木销，三个水槽之间的比例为1：2：3。通过一系列垂直图像监控木材沉积模式的时间演变和迁移率，这些图像可以识别单个原木。结果表明，木材趋向于散布在通常较小的堆积物中（<5个原木），在沉积物条的顶部具有较高的空间密度，并且由于强烈的形态变化而经常被移动。通道中存储的木材数量取决于通过非线性关系得出的原木输入速率，输入速率超过大约100个原木/小时，则决定了木材动力学的急剧变化，具有更高的存储量和更大的堵塞现象（> 10元素），不易动员。根茎的存在似乎在木材沉积中起很小的作用，但它减少了原木的平均行进距离。在三个水槽中，原木的周转率是相似的，与木材输入速率无关，并且在很大程度上类似于裸露的木条的周转率。在模拟条件下，未观察到木材对床层形态的显着影响，这表明与精细沉积物和活植物的相互作用对于形成能够引起相关形态变化的大而稳定的木材果酱至关重要。版权？ 2014约翰·威利父子有限公司

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