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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Evaluation of aDcp processing options for secondary flow identification at river junctions
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Evaluation of aDcp processing options for secondary flow identification at river junctions

机译：河转交通次流识别ADCP处理选项的评价

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摘要

Secondary circulation in river confluences results in a spatial and temporal variation of fluid motion and a relatively high level of morphodynamic change. Acoustic Doppler current profiler (aDcp) vessel-mounted flow measurements are now commonly used to quantify such circulation in shallow water fluvial environments. It is well established that such quantification using vessel-mounted aDcps requires repeated survey of the same cross-section. However, less attention has been given to how to process these data. Most aDcp data processing techniques make the assumption of homogeneity between the measured radial components of velocity. As acoustic beams diverge with distance from the aDcp probe, the volume of the flow that must be assumed to be homogeneous between the beams increases. In the presence of secondary circulation cells, and where there are strong rates of shear in the flow, the homogeneity assumption may not apply, especially deeper in the water column and close to the bed. To reduce dependence on this assumption, we apply a newly-established method to aDcp data obtained for two medium-sized (similar to 60-80 m wide) gravel-bed river confluences and compare the results with those from more conventional data processing approaches. The comparison confirms that in the presence of strong shear our method produces different results to more conventional approaches. In the absence of a third set of fully independent data, we cannot demonstrate conclusively which method is best, but our method involves less averaging and so in the presence of strong shear is likely to be more reliable. We conclude that it is wise to apply both our method and more conventional methods to identify where data analysis might be impacted upon by strong shear and where inferences of secondary circulation may need to be made more cautiously. (c) 2019 John Wiley & Sons, Ltd.
机译：河流汇合中的二次循环导致流体运动的空间和时间变化和相对高水平的形态学变化。声学多普勒电流分析器（ADCP）安装流量测量现在通常用于量化浅水河流环境中的这种循环。很好地确定，使用血管安装的ADCP的这种定量需要对相同的横截面的重复调查。但是，对如何处理这些数据的注意力较少。大多数ADCP数据处理技术都假设测量的速度径向分量之间的均匀性。由于声光与距ADCP探针的距离发散，因此必须假设在光束之间均匀的流量的体积增加。在次要循环细胞的存在下，并且在流动中存在强剪切速率的情况下，均匀假设可能不适用于水柱和靠近床的较深。为了减少对这一假设的依赖性，我们将新建立的方法应用于两个中等大小（类似于60-80米宽）砾石河流汇流的ADCP数据，并将结果与​​来自更多传统数据处理方法的结果进行比较。比较证实，在强剪的存在下，我们的方法产生不同的结果，以更传统的方法。在没有第三组完全独立的数据的情况下，我们不能实现哪种方法是最好的，但我们的方法涉及更少的平均值，因此在存在强烈的剪切可能更可靠。我们得出结论，应用我们的方法和更多传统方法是明智的，以识别数据分析可能受强剪切的影响，并且可能需要更加谨慎地制定二次循环的推论。 （c）2019 John Wiley＆Sons，Ltd。

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