Physical process-based runout modeling and hazard assessment of catastrophic debris flow using SPH incorporated with ArcGIS: A case study of the Hongchun gully

Abstract

Catastrophic debris flows frequently occur in mountainous areas after an earthquake owing to a substantially increased amount of loosened co-seismic material. Debris flows pose a serious challenge for the reconstruction of earthquake-stricken areas because of their potential reoccurrence over the course of several years after a given earthquake event. It is therefore essential to clarify the dynamics of large-scale debris flows and accurately assess the potential hazard risks. This study selected the Hongchun gully debris flow that occurred on August 14, 2010 in the areas affected by the Wenchuan earthquake in southwestern China as a typical case to analyze the formation conditions and physical processes of catastrophic debris flows. The smoothed particle hydrodynamics (SPH) method was used to reconstruct the physical process of the Hongchun gully debris flow across 3D terrain. The SPH numerical results were integrated into the ArcGIS platform to perform further spatial analysis of the hazard intensity and identify the hazard risk level. The calculated accumulated hazard area agrees well with the field data. By introducing a frequency-magnitude empirical formula, a hazard assessment model of debris flows is proposed based on flow depth and momentum, and applied to predict the potential risk of the Hongchun gully debris flow under different recurrence periods. This work provides a new method for performing hazard assessments of debris flows, and also serves as a guide for reconstruction planning in earthquake-hit areas.