The cumulative effect of culverts in impeding upstream fish passage is similar to that of large-scale high-head instream structures. The common solution to overcome this impediment is to add ancillary elements, with the goal to lower water velocities and to create discrete low velocity zones (LVZs) for fish to rest. The addition of spoiler baffles is one example of retrofitting structures with ancillary elements, with their efficacy having been proven in various field studies. The scope of the present work is to conduct a detailed laboratory study to evaluate the arrangement of spoiler baffles of different sizes and spatial density. Chosen baffle arrangements are consistent with the present size and spacing recommendations of the New Zealand Fish Passage Guidelines. Flow fields for two different flow rates within different baffle arrangements were obtained with acoustic Doppler velocimeter (ADV) technology. We show that for the standard design, as recommended in the New Zealand Fish Passage Guidelines, the maximum value of mean streamwise velocity and turbulence parameters (turbulent kinetic energy (TKE) and Reynolds stresses) is less than for two other designs we tested. However, the distribution of flow parameters within the plane is significantly different for all tested designs. In general, a shorter size baffle arranged at medium spatial density exhibits highly heterogeneous flow, with numerous LVZs, as well as providing wider pathways compared to the standard design. Wider pathways can also accommodate various fish species, which generally prefer different water velocity and turbulence, with the generated flow field allowing a lower energy cost of fish swimming whilst resting or station holding. Thus, this study shows the viability of using shorter baffles as an alternative fish passage solution for culverts, which can subsequently be validated with different fish species.

涵洞阻碍上游鱼类通过的累积效应类似于大型高水头河内结构。克服这一障碍的常见解决方案是添加辅助元素，目的是降低水速并创建离散的低速区 (LVZ)，让鱼休息。添加扰流板是带有辅助元件的改造结构的一个例子，其功效已在各种现场研究中得到证实。目前的工作范围是进行详细的实验室研究，以评估不同尺寸和空间密度的扰流板的布置。选择的挡板布置与新西兰鱼类通道指南的当前尺寸和间距建议一致。使用声学多普勒测速仪 (ADV) 技术获得不同挡板布置内两种不同流速的流场。我们表明，对于标准设计，如新西兰鱼类通道指南中的建议，平均流向速度和湍流参数（湍流动能 (TKE) 和雷诺应力）的最大值小于我们测试的其他两个设计。然而，对于所有测试设计，平面内的流动参数分布明显不同。一般来说，以中等空间密度布置的较短尺寸的挡板表现出高度不均匀的流动，具有许多 LVZ，并且与标准设计相比提供更宽的通路。更宽的路径还可以容纳各种鱼类，它们通常更喜欢不同的水流速度和湍流，产生的流场可以降低鱼在休息或停留时游泳的能量成本。因此，这项研究表明使用较短的挡板作为涵洞的替代鱼类通道解决方案的可行性，随后可以用不同的鱼类进行验证。