GREY CORRELATION METHOD BASED HAZARD ASSESSMENT OF DEBRIS FLOW IN QUAKE-HIT AREATAKING DEBRIS FLOWS IN BEICHUAN AS AN EXAMPLE

After the Wenchuan earthquake, debris flows in quake-hit area have the characteristics of smaller critical rainfall, greater scale and higher risk. Considering the effect of rainfall and earthquake, grey correlation method has been used to analyse the weights of scale, valley area, gully length, basin elevation difference, cutting density, unstable groove proportion, average annual rainfall and seismic intensity of 72 debris flow valleys in Beichuan. Thus a hazard assessment model of debris flow in quake-hit area has been established to evaluate this 72 debris flow valleys. And research results show the following: the weights of average annual rainfall and seismic intensity are greater than the other factors; the evaluation results based on the model raised in this essay are roughly consistent with those given by Liu Xilin. But the risk value improves relatively, and the risk of seven debris flow valleys among those improves a grade.