基于砾石群布置的河道生物栖息地自然化改造

Naturalization of biological habitat in river based on arrangement of gravel groups

为探讨砾石群对河道生物栖息地自然化改造效果,以江西金沙溪河段为例,采用文献调研和数值模拟的方法,选择鲢鱼为目标物种,耦合河段的平面二维水动力及栖息地模拟,研究了砾石群布置对裁弯河道生物栖息地的影响特性及自然化改造效果。结果表明:裁弯河道鲢鱼栖息地加权可用面积(A WU)明显减少,弗劳德数在其主流线附近增大,剪切速度值由原河道的横向梯度分布转变为均匀分布;砾石群对裁弯河道生物栖息地的自然化改造效果显著,其中河道凹岸高密度布置方式使鲢鱼栖息地可用面积百分率(A PU)由裁弯河道的9.20%增长至15.06%,砾石群下游附近水流的弗劳德数由裁弯河道的0.13~0.68骤降至0~0.15,砾石群下游区域形成低速水流区,为鲢鱼在大流量河道中提供了良好的庇护场所。

In order to explore the effect of gravel groups on the naturalization of the biological habitats in river,the Jinshaxi River in Jiangxi Province was used as an example to investigate the effect of gravel groups on the naturalization of biological habitats.The silver carp was selected as the target species.The effect of the gravel group layout and naturalized transformation of the curving river channel were determined through literature review,numerical simulation,and two-dimensional hydrodynamic and habitat simulation of the river reach.The results showed that the weighted usable area of the silver carp in the curving river channel decreased significantly.The Froude number of the flow increased near the main stream line of the original river,and the shear velocity value changed from the transverse gradient distribution of the original channel to a uniform distribution.The arrangement of gravels in the curving river channel significantly influenced the biological habitat.The high-density arrangement at the concave bank of the river channel increased the percent usable area of the habitat from 9.20%to 15.06%,and the Froude number of the water flow near the lower reaches of the group suddenly decreased from 0.13—0.68 to 0—0.15.Furthermore,the area downstream of the gravel group formed a low-speed flow area,which provided a good shelter for the silver carp in the channel with a large flow.