Contrary to small- and medium-sized rivers, little attention has been paid to the downstream migration of Atlantic salmon smolts in large-sized rivers and the size-related impact of hydropower stations. From 2014 to 2016, we investigated the downstream migration of n = 72 acoustic-tagged smolts in the Meuse river at a bifurcation zone between a hydropower station equipped with three Kaplan turbines and a navigation canal. A hydrodynamic model that solves the depth-integrated shallow water equations on a Cartesian grid using a finite volume technique was used to infer the influence of water discharge and flow velocity on the smolts' behaviour upstream of the hydroelectric complex. Of the migrating smolts, 41.5% performed back and forth movements before approaching the complex for the first time, sometimes over long distances and at a slow pace, leading to significant delays (3–298 h). Beyond about 250 m³ s⁻¹, the water flow direction changes towards the hydropower station with a gradual acceleration. A median water discharge of 161 m³ s⁻¹ and associated median flow velocity of 0.14 m s⁻¹ tended to favour a more direct and downstream movement towards the hydropower station. On the other hand, the navigation canal was mainly approached at low water discharge (median 132 m³ s⁻¹), due to a higher flow velocity (median 0.11 m s⁻¹) at the entrance. Of the released smolts, only 38.6% passed through the complex, of which 36.4% migrated by the navigation canal and 63.6% by the hydropower station, with a median research time of 04:44. Among all the released individuals, the escapement rate at the end of the study site was 2.9% by the canal and 8.3% by the Meuse river. This site, which offers two non-optimal, unattractive and unsafe migration routes, turns out to be problematic for successful downstream smolt migration.

与中小河流不同，大河流中大西洋鲑鱼的下游迁移和水电站规模相关的影响很少受到关注。从 2014 年到 2016 年，我们调查了n的下游迁移 = 默兹河中的 72 只带声学标记的小鲑鱼，位于配备三台卡普兰涡轮机的水电站和一条航道之间的分叉带。使用有限体积技术在笛卡尔网格上求解深度积分浅水方程的水动力模型被用来推断水流量和流速对水电综合体上游的小鲑鱼行为的影响。在迁徙中，41.5% 在第一次接近复合体之前进行了来回运动，有时是长距离和缓慢的速度，导致明显的延迟（3-298 小时）。超过约250 m ³ s ^-1，水流方向逐渐加速向水电站方向变化。平均排水量为 161 m ³s ^-1和相关的中值流速 0.14 m s ^-1倾向于更直接地向下游移动到水电站。另一方面，由于流速较高（中值 0.11 m s ^-1），航道主要在低排水量（中值 132 m ³ s ^-1）） 在入口。在释放的小鲑鱼中，只有 38.6% 通过复合体，其中 36.4% 由航道迁移，63.6% 由水电站迁移，平均研究时间为 04:44。在所有被释放的个体中，研究地点末端的逃逸率为2.9%，运河为2.9%，默兹河为8.3%。该站点提供了两条非最佳、不具吸引力和不安全的迁移路线，结果证明对于成功的下游小鲑鱼迁移存在问题。