The Research Of Debris Flow Disaster Mechanism

On the basis of theories and methodoldgies for debris flow research, this paper with G1S tool carried out in-depth studies on debris flow formation through case study of debris flow disaster prevention in Xiuyan Man Zu autonomous county , Liaoning province. The conditions debris flow formation, such as local topographical particularities, geological-geomorphologic state, hydro-meteorological conditions, soil-vegetation cover features and human impacts, have been analyzed. The history of debris flow occurrence, and debris flow types and distribution pattern in Xinyan county have been explored. There are 844 debris flow locations, of which 257 debris flows are slope debris flows, 587 gully debris flow. 207 debris flow locations are catalogued, and they scatter over 24 villages (towns). The formation and the occurrence of debris flow consist of internal factors (e.g. Provision of loose solid substances, slope saturated with water and favorable topography) and external triggers. In Xiuyan county debris flow events are typically induced by extremely intensive rain. This paper studied in detailed 4 large-scale debris flows occurred in modern times, and drew the conclusions as follows: debris flows are of explicit and typical hydrologic characteristics; heavy rain events are always immediately followed by debris flow events; the occurrence frequency of debris flow is low but the scale is big; the debris flow events are typically storm-induced ones in Xiuyan County. Debris flow activities are of typical erosion and sedimentation characteristics. There exist connections between debris flow and landslide/mountainous floods, and they can transform into each other. The paper zoned the research area into three categories according to the danger degrees of debris flows, e.g. three first-grade sub-areas, 7 second-grade sub-areas and 10 third-grade sub-areas, and also proposed measurements on debris flow prevention.