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

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.