The three-parallel-river area is referred to as the parallel drainage basins of Nujiang

Lancang and Jinsha rivers

where debris flows occur frequently.Based on analyzing the characteristics of debris flow disasters occurred in this area

five indexes including slope

lithology

fracture

vegetation and human activity

were chosen as the evaluation indices of debris flow hazards.Supported by ArcGIS

databases of debris flow hazard assessment

graphics and attribute tables were established.The study developed models for risk assessment and obtained the hazard zonation map of the area by normalizing

classification and weighting the evaluation factors.The results agreed well with the actual debris flow events and can provide an important basis for identification the potential disaster targets

optimization of disaster prevention measures and disaster reduction policy making