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<p>Braided rivers generate diverse aquatic habitats, yet their ecohydraulic functions and resilience to extreme events remain poorly quantified. This study employs a coupled two-dimensional hydro-morphodynamic and habitat model to evaluate the ecological roles of multi-threaded structures for the target species <i>Carassius auratus</i>. We analyzed six channel configurations with varying braiding intensities and main-to-secondary channel width ratios under normal, flood, and long-term (5-year) flow scenarios. Key metrics, including the Habitat Suitability Index (HSI), Weighted Usable Area (WUA), and Overall Suitability Index (OSI), were used to quantify habitat quality. Results demonstrate that morphological complexity enhances habitat stability. At Q<sub>3</sub> (2500 m<sup>3</sup>/s), the multi-threaded scenario (S0) maintained a WUA of 97.25 × 10<sup>4</sup> m<sup>2</sup> with a relatively stable OSI of 0.39, whereas the single-thread scenario (S1) exhibited severe habitat degradation, with HSP reaching 2.41%. During flood events (peak 3500 m<sup>3</sup>/s), the S3 scenario exhibited the highest resilience, with a 47% increase in suitable area compared to pre-flood conditions, primarily due to the inundation of secondary channels and floodplains. In contrast, the single-channel scenario suffered a 38% reduction in WUA. Long-term simulations indicate that, despite substantial but spatially localized bed adjustments, overall habitat quality remains stable in braided configurations. We conclude that preserving secondary channels is critical for sustaining habitat connectivity and flood resilience. Nature-based strategies, specifically secondary channel reconnection, are recommended to maximize habitable area and ensure long-term ecological stability in river management.</p>

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Numerical Ecohydraulic Modeling of Fish Habitat Conditions in Braided Rivers: The Role of Multi-Threaded Structures

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Ruida Wang,
  • Lijian Ouyang,
  • Shicheng Li,
  • Ayong Jiao,
  • Chenyang Cao,
  • Hao Zheng,
  • Xiaowei Han,
  • Shengzhi Zhou,
  • Gang Xu,
  • Xinggang Tu,
  • Weiwei Yao

摘要

Braided rivers generate diverse aquatic habitats, yet their ecohydraulic functions and resilience to extreme events remain poorly quantified. This study employs a coupled two-dimensional hydro-morphodynamic and habitat model to evaluate the ecological roles of multi-threaded structures for the target species Carassius auratus. We analyzed six channel configurations with varying braiding intensities and main-to-secondary channel width ratios under normal, flood, and long-term (5-year) flow scenarios. Key metrics, including the Habitat Suitability Index (HSI), Weighted Usable Area (WUA), and Overall Suitability Index (OSI), were used to quantify habitat quality. Results demonstrate that morphological complexity enhances habitat stability. At Q3 (2500 m3/s), the multi-threaded scenario (S0) maintained a WUA of 97.25 × 104 m2 with a relatively stable OSI of 0.39, whereas the single-thread scenario (S1) exhibited severe habitat degradation, with HSP reaching 2.41%. During flood events (peak 3500 m3/s), the S3 scenario exhibited the highest resilience, with a 47% increase in suitable area compared to pre-flood conditions, primarily due to the inundation of secondary channels and floodplains. In contrast, the single-channel scenario suffered a 38% reduction in WUA. Long-term simulations indicate that, despite substantial but spatially localized bed adjustments, overall habitat quality remains stable in braided configurations. We conclude that preserving secondary channels is critical for sustaining habitat connectivity and flood resilience. Nature-based strategies, specifically secondary channel reconnection, are recommended to maximize habitable area and ensure long-term ecological stability in river management.