A reservoir ecological flow optimization framework for multiobjective fish conservation under multipoint water...

Area of Science:

• Environmental Science
• Hydrology
• Ecology

Background:

• Large-scale water diversions for water security degrade riverine ecosystems and fish habitats.
• Existing methods struggle to balance competing water demands with ecological flow requirements in complex river systems.

Purpose of the Study:

• To develop and demonstrate an integrated framework for optimizing ecological flow allocations in rivers affected by multipoint water diversions.
• To identify critical fish habitats and quantify species-specific flow needs for conservation.

Main Methods:

• Spatial overlay analysis to identify critical habitats based on hydrological and ecological sensitivities.
• Integration of 2D hydrodynamic modeling and habitat suitability criteria (Instream Flow Incremental Methodology - IFIM) for species-specific flow quantification.
• Application of a novel Hydrological Connectivity-Habitat Function (HC-HF) coupled model to resolve flow conflicts and optimize reservoir releases.

Main Results:

• Critical spawning habitats for three endemic fish species (Hucho bleekeri, Schizothorax davidi, Schizothorax prenanti) were identified in the Dadu River headwaters.
• Optimal ecological flows were determined for H. bleekeri (70 and 21 m³/s during spawning).
• The HC-HF model application improved comprehensive habitat quality by 22.8% (weighted usable area - WUA).
• Optimized coordinated reservoir releases were calculated at 47.0 and 6.4 m³/s.

Conclusions:

• The developed framework provides a robust and transferable method for managing ecological flows in complex river systems with multiple water diversions.
• The study offers a pragmatic approach to balance human water security and ecosystem conservation goals.
• Optimized flow management can significantly enhance downstream fish habitats and biodiversity in regulated rivers.