长江中下游人工鱼礁水动力特性实验研究

EXPERIMENTAL STUDY ON THE HYDRODYNAMIC CHARACTERISTICS OF ARTIFICIAL REEFS IN THE MIDDLE-LOWER REACHES OF YANGTZE RIVER

受三峡蓄水的影响,长江中下游水文生态系统发生明显变化,导致四大家鱼产卵适宜度下降以及像中华鲟这类生殖洄游性鱼类鱼卵孵化率降低。建设人工鱼礁是缓解长江渔业资源衰退、保护长江物种多样性、保持长江渔业可持续发展的一项重要措施。基于水槽模型实验,以透空正六面体型人工鱼礁为研究对象,将鱼礁块体与护岸相结合铺设在河道岸坡上,构成鱼礁型生态护岸。通过对鱼礁型护岸周围水面线及水流流速等水力特性进行测量分析,得到了鱼礁型护岸的鱼类产卵场水力因子。结果表明：在长江中下游河道两岸铺设透空型人工鱼礁其周围水流流速可维持在0.84~1 m/s之间,处于四大家鱼产卵繁殖最适宜的流速范围内;且由于鱼礁的存在,使岸坡附近水流流速梯度增大并产生上升流及背涡流等一些复杂的水流流态,这些水力因素又刺激了四大家鱼的交配活动,增加鱼类的产卵量。

Because of the Three Gorges reservoir, the hydrological and ecological system in the middle-lower reaches of Yangtze River has changed significantly, which leaded to four major Chinese carps spawning suitability decreased and reproductive migratory fish like Acipenser sinensis eggs hatching rate decreased. The construction of artificial reef is an important measure to alleviate the decline of the Yangtze River fishery resources, protect the species diversity and maintain the sustainable development of the Yangtze River fisheries. Based on the flume experiment, the revetment blocks combined with the hollow hexahedron artificial reefs were installed in the river slope, which constituted the reeftype ecological revetment. Through the measurement and analysis of the hydraulic characteristics around reefs like water line and flow velocity, the fish spawning field hydraulic factors were developed. The results show that the flow velocity around the hollow artificial reefs maintained between 0.84m/s and 1m/s, which is in the most appropriate spawning flow rate of four major Chinese carps. Due to the existence of artificial reefs, the flow velocity gradient around bank increased and some complex flow regime included upwelling and wake vortices produced. These hydraulic factors also stimulated the mating activity of four major Chinese carps, and increased the amount of fish.