Spatial Distribution Features of Debris Flows at Active Fault Zone Along Ya-Lu Highway, China

Introduction: Active faults and accompanied tectonic activities are a key triggering factor for debris flows in mountainous region. In this paper, the spatial distribution of 19 debris flows along Ya-Lu highway in western China was analyzed. Method: We collected basic data of these 19 debris-flow gullies in the in-situ investigation work, and documented key parameters including watershed area, the averaged slope gradient, gully type, debris-flow magnitude, and developing stage of the gully. Based on the DTM data from SRTM database, the overall spatial distribution features of these debris flows are analyzed. Result and Conclusion: We used a polar coordinate system to illustrate the relationship between debris flow magnitude and the direct distance to the active fault. In this system, the spatial distribution of these debris flows is represented by the vertical distance to the fault and the angle between gullies to the fault. It is revealed that the debris-flow magnitude has a close positive relationship with the vertical distance to the active fault, that generally debris-flow magnitude increases as closing to the active fault.