Debris flow hazard assessment at Dongmatun Village in Laomao mountainous area of Dalian,Northeast China

After a heavy and continuous rainfall from July 27 to 28, 1981, geological disasters involving large debris flow affected the northern part of Wafangdian City and Pulandian City in Dalian, northeast China, and caused considerable loss of life and property. In recent years, precipitation has continued to increase significantly in Dalian, where the largest debris flow gully, named the Dongmatuncun main ditch, is situated. The Dongmatuncun main ditch is 2 km away from the north side of the right bank of the Fudu River in Wanjialing, Wafangdian City. The geomorphological and hydrological conditions, combined with the characteristics of the debris flow solid source, are conducive to debris flow development. Moreover, with an increase in rainfall, debris flow recurrence becomes increasingly likely. We study the debris flow gully in Dongmatun Village by analyzing the formation conditions through field survey. Fuzzy comprehensive evaluation and analytic hierarchy process are used to evaluate the risk of debris flow. Results indicate that the debris flow gully in Dongmatun Village is highly dangerous and debris flow occurs during heavy rainfall. In addition, the breakout of debris flow can threaten human life and property.