长江上游洛碛河段采砂后鱼类生境现状研究

近年来,长江上游大量集中采砂造成河床地貌大幅改变,进而改变了该河段原有的水流条件.采砂可能会改变鱼类生境,但采砂后的河道鱼类生境现状尚不明确.分别在2019年1月以及2020年6月、12月对洛碛河段进行了3次水声学调查,探明了洛碛河段的鱼群生境现状.基于采砂前后实测地形,分析了洛碛河段采砂前后的地形、流速、水深等参数变...

Status of Fish Habitat After Sand Mining in Luoqi Reach of the Upper Yangtze River

In recent years,with the intensive sand mining in the upper reaches of the Yangtze River,the river morphology has changed significantly and thereby also changing the original flow patterns.Sand mining may negatively impact fish habitat,of which the status of fish habitat after sand mining was not clear.This paper conducted three hydroacoustic surveys analyzed by fish sounders to ascertain the distribution of the fish habitat in January 2019 and June and December 2020.Then,based on the measured topography before and after sand mining,the change process of parameters such as topography,flow velocity and water depth before and after sand mining in the Luoqi reach was analyzed.Finally,the habitat condition of sand mining pit was evaluated by constructing fish habitat model.The survey results showed that the fish were detected in the sand mining pit,which indicating that the formed pit has gradually become a new fish habitat.The maximum density of fish swarms was 170.0 ind./1 000 m³ in June 2020,and the minimum density was 81.8 ind./1 000 m³ in January 2019.The maximum fish length on average was 17.2 cm in June 2020 and the minimum value was 14.8 cm in January 2019.The water depth was more than 20 m and the velocity decreased to less than 1.2 m/s in the generated pool after sand mining in Luoqi.The habitat evaluation model showed that the sand pit provided a larger slow-flow suitable habitat for fish in flood period.