In this paper, we firstly defined the potential debris flow gully. And then using the data of different gullies in Wenchuan earthquake hit areas, we built a discrimination model of potential debris flow gully by Fisher Linear Discrimination Analysis method. Finally, the model was used to discriminate the gullies in Jinxihe catchment, in Anxian County. Potential debris flow gully is a kind of special gully which is in a special evolution phase of the gully when the gully has the happening possibilities of debris flow but no debris flow records. Because potential debris flow can often pose more serious disasters, discrimination of potential debris flow gully is important for disaster prevention and mitigation. To build discrimination model of potential debris flow gully, a database of different gullies in quake-hit areas was established and six discrimination indices were selected based on cause analysis of debris flow. Using the database and the six discrimination indices, we built the discrimination model by Fisher Linear Discrimination Analysis method. The discrimination model was used to discriminate the gullies in Jinxihe catchment. Discrimination results showed that the discrimination model was effective and feasible in discriminating potential debris flow gullies, but it still needs further revised and perfected.

This paper presented a case analysis of debris flow hazards and its mitigation works. The Xianbuleng Gully which is located in Jinchuan County, Sichuan Province was selected as study area. This gully is an old debris flow gully which once burst out many debris flow disasters in history. If debris flows occur again in this gully, the township government, the center school and 13 village houses nearly 300 persons on the alluvial fan will be exposed to great risk.The environment settings and the hazard characteristics of the Xianbuleng debris flow were introduced first in this paper. Then, mitigation works especially the drainage canal under the optimal hydraulic condition were planned and designed in the gully for decreasing the debris flow hazards.