Cascading Landslide-Flash Flood-Debris-Flow Hazards in Central Vietnam: A Systematic Review of Mechanisms, Controlling Factors, and Research Gaps

Abstract

Landslide-flash-flood-debris-flow cascades pose a major hazard in Central Vietnam, where steep terrain, intense rainfall, and human disturbance interact to amplify disaster risk. This study systematically reviews the triggering mechanisms, spatial characteristics, rainfall conditions, impacts, and modelling approaches associated with this multi-hazard cascade. Following the PRISMA 2020 framework, 85 documents published during 2000–2025 were selected from Scopus, Web of Science, and Google Scholar and analysed using qualitative synthesis and bibliometric methods. The results show that landslides, flash floods, and debris flows are closely coupled through catchment topographic connectivity, with landslides commonly supplying sediment to drainage networks and extreme rainfall acting as the dominant transient trigger. Steep slopes, geological weakness, vegetation degradation, and anthropogenic disturbance represent major preconditioning factors. Reported rainfall thresholds vary substantially among locations and methods; Reported rainfall thresholds vary substantially among locations and methods and should therefore not be treated as a universal regional threshold. Research has increasingly shifted towards GIS, remote sensing, and artificial intelligence, although data limitations, model interpretability, and cross-hazard integration remain important gaps. An integrated conceptual framework and three research priorities are proposed: physics-informed explainable modelling, dynamic rainfall-based early warning, and standardised long-term multi-hazard databases.