GIS-based Modeling of Debris Flow Runout Susceptibility in Kulekhani Watershed, Nepal

Abstract

Rainfall-induced landslide masses often change into disastrous debris flows and damage large areas in Nepal’s mountainous region. The area covered by debris flow inundation is a most essential component for landslide hazard assessments leading to development of land use plans for saving lives and property. Because debris flow is a complex natural phenomenon, runout analysis requires very detailed information and rigorous procedures. Various empirical and dynamic models are available for debris flow runout simulation. However, a simple and publicly accessible model that can provide reasonable results is the ideal option for engineers and scientists. The Flow-R model with various algorithms has the capability to analyze debris flow inundation with limited input information, and the model software is readily available in the public domain. In this research, the Flow-R model with user-defined landslidesusceptible areas for a single rainfall event (540 mm in 24 hours) was chosen for debris flow runout analysis in Kulekhani Watershed (Nepal). The results obtained from this modeling for the debris flow inundation area was 2.68% of the watershed. The result is comparable to previously observed debris flow area in the study watershed.