进鱼口水深不足时竖缝式鱼道水力特性及进出口允许最大水深差

为研究竖缝式鱼道进鱼口水深不足时鱼道进出口允许最大水深差，构建了鱼道整体数学模型，对鱼道流速、流态、水面线等进行了数值模拟分析。结果表明：当进鱼口水深不足时，上游段水深与出鱼口水深一致，流速稳定；中间段水深开始缓慢下降，流速逐渐变大；下游段水深急剧下降，流速迅速变大，在进鱼口处出现跌水，流速出现最大值。当鱼道坡度相同时，出鱼口水深与进出口允许最大水深差呈线性关系，出鱼口水深越大，进出口允许最大水深差越大；当出鱼口水深相同时，鱼道坡度与进出口允许最大水深差也呈线性关系，鱼道坡度越陡，进出口允许最大水深差越小。

Hydraulic characteristics of vertical slot fishway and allowable maximum water depth difference between inlet and outlet subject to insufficient inlet water depth

A quasi-integrated numerical model for the vertical slot fishway was established to investigate the allowable maximum water depth difference between the fishway inlet and outlet, particularly when the fishway is subject to insufficient inlet water depth. The mathematical model was used to numerically simulate the flow velocity, flow pattern and water surface line along the fishway. The results suggest that when the water depth at the inlet is insufficient, the water depth in the upstream section is consistent with that of the outlet, and the flow velocity is stable. The water depth in the middle section begins to drop slowly, and the flow velocity gradually increases. The water depth in the downstream section decreases sharply, and the flow velocity increases rapidly. There is a drop at the inlet and the maximum flow velocity is observed. It indicates that the outlet depth has a linear relationship with the allowable maximum water depth difference between inlet and outlet, i.e., the greater the outlet depth, the greater the allowable maximum water depth difference between inlet and outlet. The results also demonstrate that there is a linear relationship between the fishway slope and the allowable maximum water depth difference between inlet and outlet, which is that a steeper slope corresponds with a smaller the allowable maximum water depth difference between inlet and outlet.