Accurate streamflow measurements are often challenging for extremely shallow rivers within complex bathymetries. In this study, a new version of the fluvial acoustic tomography (FAT) system operated by high-frequency 53-kHz underwater acoustic transducers was used to measure the discharge of a shallow mountainous river. The system was placed under a stringent site condition that was challenging for receiving pure underwater acoustic signals and hence, resulted in low-quality estimates of the river discharge. To overcome this challenge, the shortest path graph method was adopted to capture the desired hydroacoustic data, which can improve the discharge measurements significantly. The results showed that the discharge estimated by the FAT was in very good agreement with that estimated by the rating curve method, suggesting that the FAT was capable of measuring the river discharge for shallow streams when the minimum water depth for a given cross-section was greater than 28 cm. In addition, the findings of this study indicated that under the low-flow condition, the temperature variations during the daytime and nighttime along the acoustic cross-section can play an important role in reducing the signal-to-noise ratio, hence leading to sparse and weak signals of the arrival time, as recorded by the acoustic transducers.

对于复杂的等深线内的极浅河流，准确的流量测量通常具有挑战性。在这项研究中，由高频53 kHz水下声换能器操作的河流声层析成像（FAT）系统的新版本用于测量浅山区河流的流量。该系统放置在严格的现场条件下，这对于接收纯净的水下声信号具有挑战性，因此导致对河流流量的估算质量较低。为了克服这一挑战，采用了最短路径图方法来捕获所需的水声数据，这可以显着改善流量测量结果。结果表明，FAT估算的流量与额定曲线法估算的流量非常吻合，这表明当给定横截面的最小水深大于28 cm时，FAT能够测量浅水河道的流量。此外，这项研究的结果表明，在低流量条件下，白天和夜间沿声截面的温度变化可能在降低信噪比方面起重要作用，因此导致信号稀疏声换能器记录的到达时间的微弱信号。