An empirical model of subcritical bedform migration
An empirical model of subcritical bedform migration
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DOI：
10.1111/sed.12056
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发表时间：
2013-12
期刊：
影响因子：
3.5
通讯作者：
Chan‐Yi Martin Lin;J. Venditti
中科院分区：
文献类型：
--
作者：
Chan‐Yi Martin Lin;J. Venditti
预测河流河床迁移的能力对于估计河床物质负荷至关重要，然而，预测覆盖亚临界河床形成的全部条件的河床迁移（下游平移）并没有关系。本文利用野外和多个水槽数据集探讨了河床迁移速率与运移阶段之间的关系。输运阶段被定义为无量纲盾构应力除以其在泥沙夹带阈值处的值。波浪和沙丘迁移速率与迁移阶段之间存在显著的正相关。通过流动深度与粒度比对数据进行分层，可将迁移率的变异性量提高到70%左右，而迁移率的变异性可由运移阶段解释。在给定的深度与粒度比下，随着迁移阶段的增加，迁移速率增加。对于给定的输运阶段，随着流动深度与颗粒尺寸比的减小，迁移速率增加。在相同的搬运阶段，在较粗的泥沙中，河床比在较细的泥沙中移动得快。用床沙沉降速度归一化沙丘迁移速率部分地破坏了数据。考虑到来自不同来源、使用不同设备的数据集组合所产生的大量可变性，部分坍塌是显著的，值得在实验室和现场进一步测试。
The ability to predict bedform migration in rivers is critical for estimating bed material load, yet there is no relation for predicting bedform migration (downstream translation) that covers the full range of conditions under which subcritical bedforms develop. Here, the relation between bedform migration rates and transport stage is explored using a field and several flume data sets. Transport stage is defined as the non‐dimensional Shields stress divided by its value at the threshold for sediment entrainment. Statistically significant positive correlations between both ripple and dune migration rates and transport stage are found. Stratification of the data by the flow depth to grain‐size ratio improved the amount of variability in migration rates that was explained by transport stage to ca 70%. As transport stage increases for a given depth to grain‐size ratio, migration rates increase. For a given transport stage, the migration rate increases as the flow depth to grain‐size ratio gets smaller. In coarser sediment, bedforms move faster than in finer sediment at the same transport stage. Normalization of dune migration rates by the settling velocity of bed sediment partially collapses the data. Given the large amount of variability that arises from combining data sets from different sources, using different equipment, the partial collapse is remarkable and warrants further testing in the laboratory and field.