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<p>With increasingly frequent extreme rainfall events driven by global climate change, flash flood-debris flow disasters triggered by high-elevation shallow landslides are becoming more prevalent, yet their evolution mechanisms remain unclear. This study investigates the catastrophic flash flood-debris flow event that occurred on August 7, 2025, in Huangya Gully, Yuzhong County, Gansu Province, China. By integrating multi-source remote sensing, field investigation, and numerical simulation, the evolution mechanism of the disaster chain induced by high-elevation sources was systematically revealed. The results show that abundant antecedent rainfall is the critical precondition for quasi-instability of shallow landslide clusters. Dense pre-event vegetation intensified rainwater infiltration through root-induced preferential seepage pathways. This process increased the slope weight and reduced the soil shear strength, ultimately triggering widespread shallow landslides. The dynamic inversion using the Massflow model indicates that the mobilized mass reached an initial velocity of 24&#xa0;m/s. Through intense basal erosion, lateral scouring, and dam-break amplification effects, the material volume increased by approximately 32.40% along the path. This study further distinguishes the fundamental differences in causation and evolution mechanisms between this disaster chain, characterized by “cluster occurrence, shallow failure, and rapid fluidization,” and traditional chains caused by “single, deep-seated, debris-fluidized” high-elevation landslides. Finally, based on the revealed evolution mechanism, a comprehensive prevention strategy of “source regulation—process attenuation—risk avoidance” is proposed. The findings provide an important scientific basis for the prevention and control of such flash flood-debris flow disasters.</p>

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Evolution mechanism of the flash flood-debris flow disaster chain triggered by high-elevation shallow landslides: a case study of the Huangya Gully event in Yuzhong, China, on August 7, 2025

  • 期刊论文

  • 发表日期：

    2026年5月2日

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  • Yukun Wang,
  • Xingrong Liu,
  • Ziyang Xiao,
  • Yu Wang,
  • Yanjie Ma,
  • Jinyan Huang,
  • Yapeng An,
  • Boyu Li

摘要

With increasingly frequent extreme rainfall events driven by global climate change, flash flood-debris flow disasters triggered by high-elevation shallow landslides are becoming more prevalent, yet their evolution mechanisms remain unclear. This study investigates the catastrophic flash flood-debris flow event that occurred on August 7, 2025, in Huangya Gully, Yuzhong County, Gansu Province, China. By integrating multi-source remote sensing, field investigation, and numerical simulation, the evolution mechanism of the disaster chain induced by high-elevation sources was systematically revealed. The results show that abundant antecedent rainfall is the critical precondition for quasi-instability of shallow landslide clusters. Dense pre-event vegetation intensified rainwater infiltration through root-induced preferential seepage pathways. This process increased the slope weight and reduced the soil shear strength, ultimately triggering widespread shallow landslides. The dynamic inversion using the Massflow model indicates that the mobilized mass reached an initial velocity of 24 m/s. Through intense basal erosion, lateral scouring, and dam-break amplification effects, the material volume increased by approximately 32.40% along the path. This study further distinguishes the fundamental differences in causation and evolution mechanisms between this disaster chain, characterized by “cluster occurrence, shallow failure, and rapid fluidization,” and traditional chains caused by “single, deep-seated, debris-fluidized” high-elevation landslides. Finally, based on the revealed evolution mechanism, a comprehensive prevention strategy of “source regulation—process attenuation—risk avoidance” is proposed. The findings provide an important scientific basis for the prevention and control of such flash flood-debris flow disasters.