Risk Assessment And Motion Features Simulation Of Konggou Debris Flow Close To Zhirui Town

Debris flow is a kind of geological disasters which is very common in mountains,and it is also a very unique geological disaster in mountains. Debris flow usuallyoccurred in valleys and slopes where terrain is steep. It is a kind of solid-liquidtwo-phase fluid which is composed by mud, sand and stone. It is a very special floodwhich is between block movements such as landslide and collapse and sand-waterflow.Debris flow breaks out suddenly, lasts shortly and has very strong damage. Italways happens with collapses and landslides which caused serious economic losses,transport facilities damages, mine clogging rivers et al. It causes great lives andproperties losses of local people. So it should not be neglected.China has a vast area, among which, mountain areas account for two-thirds. Thespecial geological conditions, landforms and continuous or heavy rain provideconvenient conditions for the happening of debris flow. The mountain terrain is verycomplicated. This makes China one of the countries which is severely damaged bydebris flow.In this paper, we researched on the debris flow happened in Zhirui town, Keqicounty. The development situation of the debris flow was researched combining withthe data base and field survey results. The geological condition was researched fromthe following aspects namely topography, geological structure, lithology, groundwater, earthquake, meteorology, hydrology, vegetation and geological phenomenonThe current situation of the konggou debris flow was introduced frommorphology, scale and influence in detail. The geometric parameters of the debrisflow was interpreted through MPGIS software. The material sources character andvegetation situation of the forming region were described based on the field survey. The slope gradient and the formation situation of the main gully and branch gully ofcirculation region were described. The character of the debris flow was researched indetail in this way. Particle size composition of the alluvial fan was obtained throughparticle analysis experiment in situ and laboratory.Eleven factors namely drainage area, main gully length, relative depth of thedrainage basin, average slope gradient of the main gully, cutting density of thedrainage basin, loose material reserves, length ratio of sediment supply, vegetationcoverage, bending factor of the main gully, average gradient of the formation area,maximum rainfall in24hours were selected based on the character of the debris flow.Then the weights of the factors were obtained through combination assignmentsmethod based on level analysis and variation coefficient method. The risk assessmentwas conducted with extension theory. The results were compared with theconventional Liuxilin model.The development process of the debris flow was simulated using numericalsimulator FLOW3D which is widely used in hydromechanics researches. Parametersin this simulation were assigned based on some published works. The motioncharacter was analyzed based on the simulation results.