Estimation of the maximum velocity using the entropy concept in an open channel

Accurate measurements and estimations of the river flow rate are essential elements for the effective management of water resources. The stage-discharge curve is a traditional method but it has limited applicability because of the loop form characteristics, which are caused by a tidal river, the backwater effect, and the sudden changes in water level during the flood season. Therefore, various discharge estimation methods have been studied for long periods. On the other hand, measurements and estimations of the maximum velocity, which is a technically important parameter, have been difficult. If the maximum velocity can be estimated, it will be possible to determine the flow velocity because the minimum velocity is always zero at the bed under open channel flow conditions. In addition, the maximum velocity always has one value regardless of the flow conditions, such as laminar flow, turbulent flow, and a cross-sectional shape. This means that the maximum velocity is used to estimate the mean velocity. Therefore, in the present paper, an estimation formula for the maximum velocity was proposed using the entropy concept. The accuracy was verified using 12 sets measured under non-uniform flow conditions in the laboratory. A comparison of the estimated value with the value actually measured showed very high accuracy.