GPS data are usually used to measure boat velocity during boat-mounted acoustic Doppler current profiler (ADCP) measurements when bottom tracking is biased by moving bed. GPS cannot provide consistently accurate boat velocity reference because of multipath errors, satellite signal reception problems, and heading errors. In addition, the computation of water velocity from an ADCP mounted onto a moving boat is a vector-algebra problem, thus the discharge calculation is subject to the compass error when GPS is used for boat velocity reference. This paper proposes a method for correcting discharge based on the idea that the discharge calculation is independent of the boat path. The processing of two sets of boat-mounted ADCP measurements integrated with differential GPS and non-differential GPS was simulated to verify the method. The results show that the proposed method performs well in both differential and non-differential GPS conditions. The relative errors range from 0.1% to 1.5% for all measurements with the mean relative errors of 0.7%. Analytical assessment of the GPS errors shows the proposed method is insensitive to the positioning accuracy of GPS, but positioning error of non-differential GPS may induce relative discharge error of more than 1% when the river or stream is narrow. On the contrary, a relatively small compass or heading error can cause a significant error in water velocity and discharge when using GPS as the boat velocity reference. Therefore, integrating a differential GPS and maintaining a slow boat speed are best practices for discharge measurement, especially for narrow streams or short boat paths.

GPS 数据通常用于在船载声学多普勒电流剖面仪 (ADCP) 测量期间测量船速，此时底部跟踪受到移动床的偏差。由于多路径误差、卫星信号接收问题和航向误差，GPS 无法提供始终如一的准确船速参考。此外，从安装在移动船上的 ADCP 计算水速是一个矢量代数问题，因此当 GPS 用作船速参考时，流量计算会受到罗盘误差的影响。本文基于流量计算与船路径无关的思想，提出了一种校正流量的方法。对两组船载ADCP测量与差分GPS和非差分GPS相结合的处理进行了仿真验证。结果表明，所提出的方法在差分和非差分 GPS 条件下均表现良好。所有测量的相对误差范围为 0.1% 到 1.5%，平均相对误差为 0.7%。GPS误差的分析评估表明，该方法对GPS的定位精度不敏感，但非差分GPS的定位误差在河流或溪流狭窄时可能导致1%以上的相对流量误差。相反，当使用 GPS 作为船速参考时，相对较小的罗盘或航向误差会导致水速和流量的显着误差。因此，集成差分 GPS 并保持较慢的船速是流量测量的最佳实践，尤其是对于狭窄的溪流或较短的船径。