Conventional streamflow monitoring methods entail one-to-one relationships between two flow variables obtained by combining direct flow measurements with statistical analyses. These relationships (i.e. ratings) are used to monitor both steady and unsteady flows despite that in the latter cases the flow variables display an inherent hysteretic behaviour. Such behaviour is prominent if the wave passing through the gauging station is non-kinematic. This paper demonstrates that the index-velocity and continuous slope-area methods are more suitable to monitor unsteady flows in comparison with the widely used stage–discharge approach. Case studies are presented to show that, contrary to current perceptions in practical applications, hysteresis can be captured even in small streams and frequently-occurring run-off events. The paper also highlights the separation of the flow variable hydrographs in unsteady flows. This hysteresis-related aspect is less investigated so far despite having important practical implications for both hydrometric and fluvial transport applications.

中文翻译：

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重新审视流动变量在监测不稳定水流中的滞后

传统的流量监测方法需要通过将直接流量测量与统计分析相结合而获得的两个流量变量之间的一对一关系。这些关系（即额定值）用于监测稳态和非稳态流动，尽管在后一种情况下，流动变量显示出固有的滞后行为。如果通过测量站的波是非运动的，则这种行为是突出的。本文表明，与广泛使用的分段排放法相比，指数速度法和连续坡面积法更适合监测不稳定流。案例研究表明，与实际应用中的当前看法相反，即使在小流和频繁发生的径流事件中也可以捕获滞后。该论文还强调了非定常流动中流动可变水位线的分离。尽管对流体测量和河流运输应用具有重要的实际意义，但到目前为止，这种与滞后相关的方面的研究较少。