梯级拦水堰泄水口布置对草鱼上溯行为的影响

Influence of Layout of Discharge Outlet of Cascade Weir on Fish’s Migration Behavior

梯级拦水堰为改善季节性河流枯水季水面景观的工程措施,但对鱼类上溯有一定影响。为减轻拦水堰对河流的连通性及鱼类上溯活动的影响,一般需在梯级拦水堰上优化布置泄水口。针对梯级拦水堰的同侧开边口、异侧开边口、中间开口3种布置方案,通过三维水流数值模拟与水力模型试验得到了不同方案的水流流态及试验用鱼通行成功率和通行时长。结果表明,3种方案的试验用鱼平均通行成功率分别为62.2%、81.1%、55.6%,平均通行时间分别为140、133、135 s,均以方案2最优;过鱼效果与泄水口不同布置型式所造成的水流流态差异有关,垂直游动方向试验用鱼感知流速范围越大,分布范围越宽,越有利于试验鱼通行,主流附近的回流漩涡对鱼有不利诱导作用,降低了试验用鱼通行成功率。

The construction of cascade weir is an engineering measure to improve the water surface landscape of seasonal rivers in the dry season,but it has a certain impact on fish migration.In order to reduce the influence of weir on river connectivity and fish upstream activities,it is generally necessary to optimize the arrangement of discharge outlet on the cascade weir.Aiming at three layout schemes of cascade weir with side opening,opposite side opening and middle opening,the flow pattern,success rate and passage time of experimental fish were obtained by three-dimensional numerical simulation and hydraulic model test.The results show that the average passing success rates of experimental fish in the three schemes were 62.2%,81.1%and 55.6%,and the average passing time was 140 s,133 s and 135 s,respectively,and the plan 2 was the best.The effect of fish passing is related to the difference of water flow pattern caused by different arrangement types of discharge outlet.The larger the perceived velocity range and wider the distribution range of experimental fish in the vertical swimming direction,the more favorable it is for experimental fish to pass.The backflow vortex near the mainstream has an adverse induction effect on fish,which reduces the success rate of experimental fish passing.