异齿裂腹鱼通过鱼道内流速障碍能力及行为

鱼类通过流速障碍能力是鱼道设计的主要生态指标,目前国内外主要使用封闭游泳水槽进行鱼类各种游泳速度指标及游泳行为研究,其水流流态及鱼类游泳行为与鱼类通过鱼道的实际状态有较大的差距,有必要结合鱼类游泳速度指标来探索能够更加准确量化鱼类通过鱼道流场的游泳能力测试方法。首先,在封闭游泳水槽中通过速度递增法测得异齿裂腹鱼临界游泳速度(101.01±20.86 cm/s)和突进游泳速度(196.94±21.80 cm/s);然后,以临界游泳速度和藏木水电站鱼道竖缝流速(110.00 cm/s)为参考,通过在开放游泳水槽内加不同束窄梯形体,形成类竖缝式鱼道的鱼类自主游泳能力测试水槽,开展两种底坡条件下4级短竖缝(工况1和工况2竖缝流速为101.55±14.87 cm/s、114.63±24.28 cm/s,竖缝顺水流长度均为40 cm)和单级长竖缝(工况3竖缝流速为137.45±17.63 cm/s、竖缝顺水流长度为160 cm)下试验鱼通过流速障碍能力和行为研究。试验结果表明:工况1、工况2下试验鱼通过4级竖缝成功率分别为82.05%、84.62%,通过流速大于临界游泳速度的竖缝时,持续爆发游泳时间为0.52±0.34 s;工况3下93.33%试验鱼以209.43±21.76 cm/s游泳速度成功通过单级长竖缝;3种工况下试验鱼通过流速大于临界游泳速度的竖缝时,以与突进游泳速度无显著性差异(P0.05)的恒定游泳速度(214.01±30.64 cm/s)上溯。鱼类游泳轨迹与流场耦合分析表明:鱼类上溯所需时间及路径长度与其选择的游泳路径密切相关,试验鱼通过借助回流区同向水流推动,增加上溯效率。本文研究方法及研究结论可为鱼道设计、改造、评价提供依据。

Assessing the swimming ability and performance of Schizothorax oconnori to cross velocity barriers in fishway

The ability of fish to cross velocity barriers plays an important role in the design process of a fishway. Various swimming speed indicators and behaviors of fishes were mainly determined by tests conducted in closed swim chambers, where current conditions and fish performance are different from that of fishways. Therefore, it is necessary to explore a new experimental protocol of which the experimental channel has similar flow field with fishway to study the swimming ability. Firstly, the critical swimming speed (101.01 ±20.86cm/s) and the burst swimming speed (196.94 ±21.80cm/s) of fish were acquired in swim chambers by velocity increment tests. Secondly, based on the critical swimming speed of fish and the designed flow speed at vertical slot of Zangmu Hydropower Station''s fishway (110.00cm/s), an experimental channel with vertical slots for testing volitional swimming ability of fish was built by setting different trapezoid barriers in the channel. After this, the swimming tests of Schizothorax oconnori to cross water velocity barriers were carried out with two different barrier layouts. For one layout, the channel has four steps in two gradients (the flow speed in velocity barrier of condition 1 was 101.55 ±14.87 cm/s, while condition 2 was 114.63±24.28 cm/s), for the other layout, the channel has only one step (the flow speed in the 160 cm long velocity barrier of condition 3 was 137.45±17.63 cm/s). The fish in condition 1 has a success rate of 82.05% to cross four step barrier while it was 84.62% in condition 2; it costs fish 0.52±0.34s in condition 1 and condition 2 to swim continuously to cross the slot which has flow speed greater than critical swimming speed; 93.33% fish in condition 3 cross the single step barrier successfully in a swimming speed of 209.43±21.76 cm/s; the swimming speeds(214.01±30.64 cm/s)in all three conditions were not significantly different from burst swimming speed of fish (P >0.05). The swimming trajectories of fish and the corresponding flow field show that the time cost and path length for fish to swim upstream is closely related to the path fish choose. Fish reduce its time cost and path length to swim upstream by taking advantage of flow which is in the same direction with fish movement. This method and result of this research could provide reference for fishway design,modification and evaluation.