都柳江梅林航电枢纽工程对鱼类产卵场功能影响研究

Study on Influence of Meilin Navigation and Power Junction Project of Duliujiang River on the Function of Fish Spawning Ground

为探究流域梯级开发水文条件变化对鱼类产卵的影响,本文以都柳江丙妹滩河段为研究对象,开展鱼类资源和鱼类栖息地调查,结合梅林航电枢纽工程开发特性,采用《环境影响评价技术导则地表水环境》(HJ 2.3—2018)推荐的平面二维恒定流水动力数学模型,模拟在频率P=10%典型月来水条件下,工程调度运行对鱼类产卵场功能的影响。研究表明:在频率P=10%典型月来水条件下,梅林航电枢纽工程建设后,丙妹滩鱼类产卵场受工程回水影响最大长度为1.9 km,产卵场上、中、下控制断面月均水深与工程前相比分别加大了0.051 m、0.528 m和0.928 m,月均流速与工程前相比分别减小了0.022 m∕s、0.016 m∕s和0.171 m∕s,流速的变化规律体现为入库流量偏枯时,水深变化更大,流速减缓更明显;工程前后产卵场河段的水深、流速、流量变化幅度不大,产卵场所在河段水文条件未发生明显变化,仍然能够满足绝大多数鱼类产卵水文需求,梅林航电枢纽工程建设对丙妹滩鱼类产卵场功能没有明显影响;优化工程运行方式可以减缓工程建设对鱼类资源的影响。

In order to explore the impact of changes in the hydrological conditions of cascade development on fish spawning in the river basin,the Bingmeitan section of Duliujiang River was taken as the research object,fish resources and fish habitat were investigated,and combined with the engineering characteristics of Meilin navigation and power junction project development plan,the planar two-dimensional constant flow hydrodynamic mathematical model recommended by Surface Water Environment,Technical Guidelines for Environmental Impact Assessment(HJ 2.3—2018)was used to simulate the impact of engineering scheduling operation on the function of fish spawning grounds under the condition of 10%typical monthly water frequency.The results show that under the typical monthly water condition of frequency P=10%,after the construction of the Meilin navigation and power junction project,the maximum length of the fish spawning ground affected by the backwater is 1.9 km,the average monthly water depth of the upper,middle and lower control sections of the spawning ground increased by 0.051 m,0.528 m and 0.928 m,respectively,compared with that before the project,and the average monthly flow velocity decreased by 0.022 m∕s,0.016 m∕s and 0.171 m∕s,respectively.The variation law of flow velocity is reflected in the fact that when the inflow is relatively low,the greater the change in water depth,the more obvious the decrease in flow velocity.The water depth,flow velocity and flow of the spawning ground before and after the project did not change much,and the hydrological conditions of the spawning site in the river section did not change significantly,which could still meet the hydrological needs of most fish spawning.Optimizing the operation mode of the project can reduce the impact of the project construction on fish stocks.