Numerical Modeling of Debris Flow Originating from Topographic Hollows at Koyalghari and Simaltal Area along Narayangadh-Mugling Highway
DOI:
https://doi.org/10.64862/ajeg.2025.201.02Keywords:
Cohens Kappa, Debris flow, LISEM model, Physical based modelling, Runout distance, MuglingAbstract
Assessment of debris flow runout extent is essential for evaluating landslide hazards and formulating effective land-use plans. This study employed the openly available LISEM (LImburg Soil Erosion Model) to simulate debris flow runout using diverse geospatial and geotechnical input data. By incorporating the spatial distribution of soil geotechnical parameters, the model effectively estimated debris flow runout based on debris height. The research integrates rainfall-induced slope failure and runout dynamics through a physically based modeling approach to predict potential landslide impact zones under extreme rainfall conditions corresponding to 5-, 10-, and 25-year return periods. The study area is the Koyalghari region along the Narayangadh-Mugling Highway in central Nepal. Model validation was conducted in the Simaltal area using the Cohen’s Kappa statistic, yielding a value of approximately 0.7, which indicates substantial agreement with observed debris flow patterns. For the analyzed rainfall scenarios, the estimated average debris flow height ranged from 0.92 m to 1.1 m on the highway, highlighting the potential for severe damage to road infrastructure and traffic during extreme events. Overall, the study demonstrates that a physically based model incorporating geotechnical soil parameters can reliably estimate debris flow runout and deposit height, offering valuable insights for hazard assessment, risk mitigation, and land-use planning in landslide-prone regions such as the Narayangadh-Mugling Highway.
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