Prior studies demonstrate that bottom velocity measurements from Doppler sonar systems are proportional to bedload transport rates. These observations suggest that acoustically based systems offer a capability for rapid sampling of bedload transport processes. Before these measurements can be fully utilized, validation and understanding of the sampling mechanism are essential. We explore the measurement mechanism through a series of laboratory trials with a field instrument, the multi‐frequency coherent Doppler profiler (MFDop). The MFDop system is a multi‐frequency (1.2–2.2 MHz), bistatic Doppler sonar that provides three‐component ensemble‐averaged velocity profiles over a ∼30 cm depth interval with up to 1 mm resolution at a rate of 50 profiles/sec. Tests of the MFDop system were carried out in the main flume in field‐scale conditions at the St. Anthony Falls Laboratory (SAFL) using 1 ms⁻¹ mean flows over a mobile bed of sand with median grain size d₅₀ = 0.4 mm. We find agreement between MFDop transport measurements and measurements based on bedform migration rates, and sediment traps built into the SAFL flume. Predictions using the Meyer‐Peter and Müller (1948) empirical equation closely match our observations while in contrast, predictions using the Nielsen (1992) equation are a factor of two higher.

中文翻译：

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脉冲相干多普勒廓线仪测量床载运移

先前的研究表明，多普勒声纳系统的底部速度测量值与床载运输速度成正比。这些观察结果表明，基于声学的系统提供了对床载运输过程进行快速采样的功能。在充分利用这些测量值之前，必须对采样机制进行验证和理解。我们通过一系列现场试验，使用多频相干多普勒测绘仪（MFDop）进行现场试验，探索了测量机制。MFDop系统是一种多频（1.2–2.2 MHz）双基地多普勒声纳，可在30厘米深度的间隔内提供三分量整体平均速度剖面，分辨率为1毫米，速度为50剖面/秒。MFDop系统的测试是在St.^-1平均流量流经中值粒径d ₅₀  = 0.4 mm的沙子移动床。我们发现，MFDop运移测量与基于床形迁移率的测量以及SAFL槽中内置的沉积物捕集器之间存在一致性。使用Meyer-Peter和Müller（1948）经验方程式进行的预测与我们的观察结果非常吻合，而相比之下，使用Nielsen（1992）方程式进行的预测则高出两倍。