Study On Hazard Assessment Of Debris Flow In Ya'er Gully Of Pingliang City

Ya'er Gully,located in the southwest of Pingliang city,is a debris flow ditch which have the mot serious geological disasters in Kongtong District.In recent years,several large-scale debris flow disaster occurred,which caused enormous direct economic losses,and negative influences on the living environment of Kongtong District.Ya'er Gully is urgently needed to governance.In this paper,the geologic environment,the formation conditions,hazard characteristics and development trend of debris flow are analyzed in detail.The risk of debris flow is evaluated and the danger range is predicted.The conclusions of this research are as follows:(1)The general characteristics of the debris flow in Ya'er Gully is summarized.According to the formation process,flow and accumulation of the debris flow in Ya'er Gully,and the watershed area is divided,the handling mechanism is analyzed to determine the source and recharge of the loose supply.(2)The risk of debris flow is evaluated by traditional model and fuzzy analytic hierarchy process.The results of the two models were compared and analyzed.The results of fuzzy AHP were compared with the field survey,and superior to the traditional evaluation model in the evaluation factors selection and the making of the evaluation criteria.(3)Combined with the characteristics of the debris flow accumulation of the Ya'er Gully,that the maximum of length,width,extent and range of the debris flow of the Ya'er Gully are predicted by using the basin foreground prediction method,and the hazard zone and the affected area of the debris flow are divided.(4)The Ya'er Gully flow control scheme is composed by comparing and analysing the advantages and disadvantages of the three schemes,comprehensive management scheme is recommended(blocking,anti-erosion,bank protection measures combined).