Abstract:“5·12” Wenchun Earthquake resulted in large numbers of geo hazards along Dujiangyan Wenchuan Highway located in the zone of extreme quake areas. After this earthquake

most of valleys have favorable conditions for debris flow occurrence and are very active in the future 10~20 years

especially the beginning 5years after this earthquake. This paper mainly discussed and assessed the hazard levels of debris flow valleys based on the data of field investigation and high resolution remote sense image identification. The hazard assessment model for single debris flow valley was established using valley slope gradient and debris flow magnitude

and 29 debris flow valleys were assessed by this model and classified into 4 hazard levels of extreme hazard

high hazard

middle hazard and gentle hazard. The assessment result showed that most of debris flow valleys were in and over middle hazard level

occupied 79.31% and the valleys of extreme hazard level accounted for 20.7%. The most hazard valleys were Guozhupu valley

Manianping valley

Yeniu valley

Yiwanshui valley and Gaodianzi valley

and then were Xinqiao valley

Qinjin valley

Fendan valley and Cili valley. These valleys should be pay specific attention and make effective measures to predict

evade and prevent debris flow in the earthquake reconstruction projects.