耦合水文情势及鱼类繁殖的江垭水库生态调度需求研究

Ecological Operation of Jiangya Reservoir Coupled with River Hydrologyand Fish Reproduction

为了修复河流水文情势、维持河流生态系统健康,通过环境DNA采样、IHA水文指标变动分析和文献资料总结等方法,开展了江垭水库坝下水文情势及鱼类繁殖需求关系研究,提出了水库生态调度需求与建议。结果显示,2021年9月在溇水干支流综合调查获得鱼类55种,与20世纪90年代相比,流水性种类在干流江段显著减少了51.35%;按照生态调度优先等级评估原则,确定江垭水库生态调度的主要目标物种为产漂流性卵的银鲴(Xenocypris argentea)、银鮈(Squalidus argentatus)、贝氏䱗(Hemiculter bleekeri)和产粘沉性卵的鲤(Cyprinus carpio)、鲫(Carassius auratus);江垭建坝前后下游水文情势变化较大,发生高度改变且对鱼类洄游产卵及鱼卵发育有重要作用的水文指标包括年最大1日、3日平均流量指标、年出现高流量脉冲事件的次数和持续时间以及连续日流量上涨率。研究表明,以促进坝下不同产卵类型的鱼类繁殖为目标,生态调度需要一定的高流量脉冲次数和历时,还需要控制下游水位的日降幅,通过泄放合理的生态流量来维持下游鱼类的生物多样性。

The ecological operation of large reservoirs is an important means of restoring the hydrologi⁃cal regimes of rivers and the health of river ecosystems.Jiangya reservoir,located in Cili County,Zhangji⁃ajie,on the lower Loushui River,is a large reservoir and is important for flood control in the Lishui River basin.However,fish populations in Loushui River have been declining,and restoration and the need for conservation of the resource is urgent.In September 2021,a comprehensive fishery resource in⁃vestigation was carried out in the mainstem and tributaries of the middle and lower Loushui River,in⁃cluding environmental DNA sampling,fish collection and fisherman surveys.The fishery composition and distribution,and variations in the hydrological regime below Jiangya Dam,before and after reservoir construction,were analyzed.The analysis was based on the investigation of fishery resources and aquatic habitat,combined with long term hydrological data collected at Changtanhe Hydrologic Station(1960-2020),and target fish species were selected for the ecological operation.We then explored the relation⁃ship between the hydrology below Jiangya Dam and fish reproduction by analyzing variations in the Index of Hydrological Alteration(IHA)and a review of the literature.Finally,requirements and recom⁃mendations for the ecological operation of Jiangya Reservoir were put forward.A total of 55 fish species were recorded in the mainstream and tributaries of Loushui River in September 2021.The number of rheo⁃philic fish species in the mainstream decreased significantly(51.35%)compared to the 1990s.According to the priority evaluation of target fish species for the ecological operation,the primary target species are Xenocypris argentea,Squalidus argentatus,Hemiculter bleekeri that lay drifting eggs,and Cyprinus car⁃pio,Carassius auratus that lay sticky eggs.Before and after the construction of Jiangya Dam the hydro⁃logical regimes in the lower reaches have changed greatly.The hydrological indicators that most changed and play important roles for fish migration,spawning and fish egg development include the annual maxi⁃mum 1-day and 3-day average flow,number and duration of high-flow pulse events in a year,and con⁃tinuous daily flow increase rate.To promote fish spawning below the dam that includes different types of eggs,the ecological operation of Jiangya reservoir needs to maintain a sufficient number and duration of high flow pulses,and control the daily decline of downstream water level.These hydrologic characteris⁃tics are important for maintaining a diversity of downstream aquatic organisms and are achievable by eco⁃logical operation.