Coupled modeling framework for proactive design of debris-flow barrier placements

This study presents a coupled modeling framework for the proactive design of debris-flow mitigation strategies, with a particular focus on optimizing barrier placements. In response to the increasing risks posed by debris flows in mountainous regions, the framework integrates physically based modeling and data-driven methods across four interlinked phases: shallow landslide initiation, debris-flow mobilization, runout simulation, and barrier design. Site-specific geomorphological, geotechnical, and hydrogeological conditions were incorporated to enhance modeling accuracy. Key debris-flow parameters-including initial volume, entrainment rate, and basal friction angle-were estimated using field-based indices and statistical regressions, then applied to the DAN3D dynamic model for simulating debris-flow behavior. Monte Carlo simulations produced velocity and thickness distributions with mean values of 20.86 m/s and 4.09 m, and 99th percentile values (28 m/s and 4.5 m). These extreme-case predictions aligned well with observed peaks from the 2011 Mt. Umyeon debris-flow event, supporting the reliability of the proposed framework. Barrier performance evaluations for two alternative configurations showed that strategic placement significantly reduces downstream impact intensity. Despite remaining uncertainties, such as spatial variability in material properties and real-world complexities, the framework offers a systematic and adaptable approach to debris-flow hazard assessment and infrastructure protection, supporting informed disaster risk reduction in mountainous terrains.