Hydrodynamic creation technique for important fish habitat experimental sites in the Yichang section of the middle reaches of the Yangtze River

Understanding the hydrodynamic requirements of key life-history stages of fish in their natural habitats is not only a fundamental scientific basis for comprehending fish ecological habits but also a core prerequisite for implementing river ecosystem restoration and biodiversity conservation. This study focuses on the Acipenser sinensis in the middle reaches of the Yangtze River, selecting the natural fish habitat at Yanzhiba, a bifurcated channel in the Yichang section, as the study area. This region serves as an important spawning and habitat ground for the Acipenser sinensis, where hydrodynamic conditions significantly influence its reproductive behavior. The research systematically analyzes the impact of different flow-inducing methods on the hydrodynamic characteristics of the bifurcated channel test area under two typical hydrological conditions: no natural flow and low natural flow. Through quantitative analysis, the study explores the variation patterns of suitable habitat areas for the Chinese Sturgeon under different flow conditions and establishes an experimental method for determining the hydrodynamic habitat requirements of key fish species in a controlled natural environment. The results demonstrate that combining natural inflow conditions with the operation of flow-inducing pumps can effectively simulate and optimize the hydrodynamic environment for Chinese Sturgeon habitats. Under experimental conditions, suitable habitat areas with high flow velocities (>0.6 m/s), accompanied by specific levels of vorticity and turbulent kinetic energy, were formed. Furthermore, the suitable habitat area shows a significant increasing trend with the enhancement of natural inflow and flow-inducing pump operation, indicating that rational regulation of hydrodynamic conditions can effectively expand the suitable habitat range and enhance the potential for fish population recovery. This method not only meets the hydrodynamic demands of fish habitat experiments in controlled natural environments but also provides a new research paradigm and technical approach for restoring fish habitats in river ecosystems. By integrating natural inflow with artificial flow-inducing techniques, the research achieves precise regulation of complex hydrodynamic environments, offering scientific support for the conservation and habitat restoration of endangered species like the Chinese Sturgeon.