Study on ecological flow processes based on fish habitat requirements

Abstract

[Objective] To effectively address the issues of damaged river habitat structure and functional degradation. [Methods] The Lingshou section of the Hutuo River Basin was selected as the study area. Based on field surveys, ecological monitoring, literature research, and numerical simulations, the concept of hydraulic units was introduced. Target fish species were scientifically selected, and their hydrological and geomorphic habitat requirements were systematically summarized. The spatial distribution of habitats for different fish species during key stages under hydrological variations was quantitatively analyzed. [Results] The result revealed significant differences in the spatial distribution of hydraulic units at different flow rates. The hydraulic unit diversity index reached its maximum value at a flow rate of 200 m³/s. When the flow rate was 120 m³/s, the area of deep pools reached a maximum of 796 956 m². At a flow rate of 240 m³/s, the area of rapids reached a maximum of 1 005 619 m². Based on the habitat requirements of four target fish species, the ecological flow process in the study area was determined. During the concentrated spawning period from May to June, the ecological flow ranged from 200 to 240 m³/s. During the overwintering period, it ranged from 80 to 120 m³/s, and during the foraging period, it ranged from 120to 200 m³/s. [Conclusion] Through quantitative analysis of the spatiotemporal distribution of hydraulic units and comprehensive consideration of the needs of key species at different stages of life cycle, the ecological flow process of the damaged river was dynamically determined in stages. The findings provide theoretical support for the ecological restoration of regional rivers and lakes.

Keywords

fish habitat / different life cycle stages / numerical simulation / ecological flow / hydraulic unit / Hutuo River / environmental DNA