异侧布置竖缝式鱼道紊流结构试验研究

鱼道是辅助鱼类克服障碍物,实现产卵洄游、索饵洄游和越冬洄游的通道。全球目前已建鱼道中,鱼类能够溯游通过的鱼道尚不足50%,大多数鱼道的水力设计仅考虑平均流速,忽略了鱼道内的紊流结构,探究鱼道的水力特性尤其是紊流结构,对改进其设计具有重要的指导意义。通过在大比尺水槽模型中试验研究异侧布置竖缝式鱼道的紊流结构,利用声学多普勒测速仪(ADV)实测竖缝式水池内每一点的三维瞬时流速,剖析流场的三维时均流速分布、流动特征、旋涡特性、纵向和横向紊动强度分布、不同水平面的雷诺应力分布等,考虑了两种典型流量(Q1=20.62 L/s,Q2=30.75 L/s)和3个特征水平面(h/3,h/2和2h/3),提出了三维流速分布的半理论半经验公式、流场矢量图及各点的旋度,并与自由壁面射流进行比较。结果表明,异侧布置竖缝式鱼道前半池内纵向流速具有壁面射流的特征,后半池由于受下游隔板的阻挡则偏离壁面射流规律;水池内存在顺时针方向的水平旋涡,其旋度随流量的增大而增强;前半池壁面射流区的紊动强度存在峰值区,后半池的紊动强度峰值区由水槽左侧移至右侧;壁面射流区的雷诺应力变幅较大,而在旋涡区则较小,有利于洄游鱼类在鱼道上溯和歇息。     

基于鱼类行为学与水力学的水电站鱼道进口位置选择

鱼道进口位置选择属于鱼类行为学与水力学交叉研究范畴,设置的合适与否直接影响鱼道工程的过鱼效果。根据过鱼对象的游泳能力和生活习性,提出了将下游河道内区域划分为鱼道进口优选区域、鱼道进口备选区域及鱼道进口禁布区域的方法和思路。以某大型水电工程为例,在鱼类行为学基础上,通过对水电站下游流速和流场等水力特性进行分析,结果表明:左岸存在低流速带,鱼类可顺利上溯至尾水渠附近,为鱼道进口主要布置区域;综合生物学指标和水力学指标,利用回流屏障建议将鱼道进口布置于桩号0+200~0+210 m范围内;考虑到部分上溯性较强的鱼类,建议在电站发电机组上方布置备用进口。该研究可为水电工程鱼道进口位置选择提供参考。     

欧洲河流鱼类洄游通道恢复的研究与实践

欧洲各国虽然国情不同,但在鱼类保护问题上均面临着类似的难题,即如何恢复洄游鱼类的洄游通道;各国在该问题上密切合作与信息共享,取得了良好的效果,积累了丰富的经验。介绍了欧洲“共同体河流”项目恢复鱼类洄游通道的解决办法、监测与评价、信息交流等方面的研究与实践。     

浅议我国鱼道运行管理存在的问题及对策-以洣水洋塘鱼道为例

鱼道作为能够有效联通闸、坝上下游水流,为鱼类提供上溯、下行通道的有效途径,一直以来被作为水利水电工程建设鱼类保护的重要措施采用,但由于认识、经费、运行管理等多方面因素,其过鱼效果及发挥的作用难以被肯定。本文在综述国内外鱼道运行管理体制现状基础上,以洣水洋塘鱼道为例,分析总结了该鱼道兴衰历程,提出我国鱼道运行管理应提升对过鱼设施建设必要性的认知度、捋顺管理机制体制、建立生态补偿机制的对策与建议,力求能够为鱼道这项鱼类保护措施的建设与发展提供支持。     

我国过鱼设施现状分析及鱼道适宜性管理的关键问题

水电开发对于洄游性鱼类产生的负面影响最为直接,阻碍了其繁殖、索饵以及越冬等生命行为。在调查的25个水电项目中,有17个采取了鱼类保护措施,其中采取增殖放流措施的占82.4%,仅有1个项目修建了鱼道。介绍了“莱茵河-2000计划”和哥伦比亚河鱼道建设及运行效果。鱼道不单纯是洄游性鱼类的通道,更是实现大坝上下游物质与能量循环的生态廊道。国内开展鱼道适应性管理的关键问题是：建立鱼道长效运行与保障机制,对鱼道过鱼进行长效监测以及研究鱼道过鱼效果评价方法。     

Climbing success of adult Pacific lamprey on a vertical wetted wall

The ability of adult Pacific lamprey, Entosphenus tridentatus (Gairdner), to climb has enabled development of lamprey‐specific fishways. Sheer vertical climbing elements are needed for these structures when fishway installation space is limited. A 1.6‐m high aluminium wetted wall was built to test Pacific lamprey vertical climbing in relation to flow and three water delivery mechanisms: overflow, upwelling and sidewelling. Passage success and passage times were recorded for individual Pacific lamprey (n = 122). For those that interacted with the structure (n = 104), 94% successfully ascended the wall (76% on their first attempt). Average time from first interaction with the structure to exit ranged from 19.5 to 47.0 min. Success rates and passage times were not significantly affected by flow or water delivery treatments. This indicates that vertical elements can facilitate lamprey passage in the 0.13–3.59 L min^?1 cm^?1 flow range tested and may greatly expand the design alternatives in certain situations.     

Biological effectiveness of an inexpensive nature‐like fishway for passage of warmwater fish in a small Ontario stream

Few studies have been conducted to evaluate the effectiveness of nature‐like fishways, particularly in low gradient warmwater streams with diverse fish communities. We evaluated a nature‐like fishway that was installed to facilitate upstream passage at a low head dam on Indian Creek near Spencerville, Ontario, Canada. A passive integrated transponder (PIT) array was used to quantify attraction and passage efficiency for 391 PIT tagged warmwater fish, represented by seven species. Attraction efficiency for the three most common species, common shiner (Luxilus cornutus), creek chub (Semotilus atromaculatus) and white sucker (Catostomus commersonii), was 63.3%, 83.7% and 65.6%, respectively, and passage efficiencies were 5.1%, 38.4% and 25%, respectively. Creek chub were able to locate the fishway in less time than white sucker and common shiner; however, took longer to successfully pass. Manipulation of creek chub release locations was used to separate issues of attraction and passage and revealed that passage efficiency was highest (76.2%) for those released within the fishway and intermediate for those released at the entrance (42.1%). This multispecies fishway improved stream connectivity, but additional work is needed to fine tune its configuration. Similar projects that engage stakeholders in nature‐like fishway construction are a promising approach for the thousands of small dams that occur on low gradient streams around the globe, but those studies should incorporate a biological evaluation to ensure that attraction and passage efficiency are optimised.     

Use of a vertical-slot fishway by galaxiids in Western Australia

Abstract –  The Goodga River Fishway is the first vertical-slot fishway in Western Australia and was opened in April 2003 with the aim of increasing the habitat available to two galaxiids; the trout minnow ( Galaxias truttaceus ), a highly restricted freshwater fish species in Western Australia, and the widespread common jollytail ( Galaxias maculatus ). The fishway was designed to function during low flows to coincide with the upstream spawning migration of G. truttaceus . Prior to the opening of the fishway, no fish were found above the Goodga River gauging station (weir), which is approximately 2 km upstream of the river's entrance to Moates Lake. Fish migrations were monitored in each season between April 2003 and February 2005. Galaxias truttaceus utilised the fishway in all sampling periods. Adult fish migrated up the fishway prior to spawning, while large numbers of new recruits (small juveniles) negotiated the fishway during November 2003 and 2004. More G. truttaceus and G. maculatus were captured on the fishway during daylight hours compared with the night; however, larger G. truttaceus were more commonly captured at night whereas G. maculatus on the fishway were larger during the day. The fact that fishway utilisation by G. maculatus was consistent during all samples and new recruits migrated during periods of low flow demonstrates the importance of understanding the migration patterns of the target species when designing fishways.     

Efficiency of a nature-like bypass channel for sea trout (Salmo trutta) ascending a small Danish stream studied by PIT telemetry

Abstract – Upstream passage of adult sea trout ( Salmo trutta ) in a nature-like bypass channel was investigated in the Tirsbæk brook, Denmark, in autumn and winter 1999/2000. Sea trout were caught by electrofishing up- and downstream of the weir at which the bypass was situated. Fish were tagged with passive integrated transponder (PIT) tags and released downstream of the weir. Automatic PIT-tag logging stations were positioned downstream, in the lower part, and at the upstream exit of the bypass to investigate the passage success of the fish. The bypass was neither size- nor sex-selective in the size ranges investigated. The majority (68%) of fish approached the bypass at night. Over 90% of tagged upstream-searching fish located and entered the bypass channel, but only about half of them passed through. The inefficiency is suggested to be because of a combination of the length of the bypass channel and inadequate flow in the bypass channel.     

不同位置和朝向的鱼道进口诱鱼效果

为了探明不同进口朝向的布置方式和进口位置对诱鱼效果的影响，本研究通过建立鱼道进口概化模型，设计3种环境流速工况，以马口鱼为实验对象，针对不同朝向和不同位置鱼道进口分别进行放鱼实验。结果显示，在同一鱼道进口位置时，垂直于河道水流方向上的鱼道进口其诱鱼效果明显优于顺河道水流方向的鱼道进口；当开启与电站不同相对位置不同的进口时，其诱鱼效果受河道水流速度和进口位置的影响较为显著；在所设计实验工况中，环境流速为0.3 m/s时，鱼道进口诱鱼效果最好。研究结果将对水利工程中鱼道进口布置具有重要的参考意义并指导工程实践。