An acoustic travel time method for continuous velocity monitoring in shallow tidal streams
An acoustic travel time method for continuous velocity monitoring in shallow tidal streams
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DOI：
10.1002/wrcr.20375
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发表时间：
2013-08
影响因子：
5.4
通讯作者：
M. Razaz;K. Kawanisi;I. Nistor;S. Sharifi
中科院分区：
文献类型：
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作者：
M. Razaz;K. Kawanisi;I. Nistor;S. Sharifi
利用河流声学层析成像（FAT）系统通过一条传输路径测量潮汐通道中流量的长期变化。FAT是一种创新的声学技术，利用旅行时间方法确定穿过整个水流横截面的多条射线路径中两点之间的速度。由于水流分布的高度空间变异性，固定ADCP测量不太可能产生真正的断面平均流速，因此使用移动船ADCP方法提供参考数据。因此，作者进行了两次短期移动船ADCP活动。在第一次活动中，一对夫妇的声学站被添加到FAT系统，以解决流动的角度，除了平均速度。FAT结果与相应ADCP断面平均流向和流速的比较显示出显著的一致性。第二个活动的目的是捕捉盐楔侵入声传播模式的影响。有人发现，FAT的速度测量偏高，如果声学站位于较冷的淡水层内。射线追踪后报表明，在盐楔内安装声学站可以显着改善系统的输出功能。通过比较从长期FAT走时记录中评估的盐度与电导率-温度传感器提供的节点盐度测量值，揭示了FAT测量盐通量的潜在能力。
Long‐term variations of streamflow in a tidal channel were measured using a Fluvial Acoustic Tomography (FAT) system through one transmission path. FAT is an innovative acoustic technology that utilizes the time‐of‐travel method to determine velocity between two points from multiple ray paths that traverse the entire cross‐section of stream. Due to high spatial variability of flow distribution stationary ADCP measurements were not likely to yield true section‐averaged flow velocity and moving‐boat ADCP method was therefore used to provide reference data. As such, two short‐term moving boat ADCP campaigns were carried out by the authors. In the first campaign, a couple of acoustic stations were added to the FAT system in order to resolve flow angularity in addition to the mean velocity. Comparing the FAT results with corresponding ADCP section‐averaged flow direction and velocity indicated remarkable consistency. Second campaign was designed to capture the influence of salt wedge intrusion on the sound propagation pattern. It was found that FAT velocity measurements bias high if acoustic stations lay inside the cooler freshwater layer. Ray‐tracing hindcasts suggest that installing acoustic stations inside the salt wedge may significantly improve function of output of the system. Comparing salinities evaluated from long‐term FAT travel time records with nodal salinity measurements provided by conductivity‐temperature sensors reveals the potential ability of FAT in measuring salt flux.