Risk Assessment Of Gancha Gully Debris Flow In Hu County At The Northern Piedmont Of The Qinling Mountains

In china,mountainous area is widely distributed.A special geological disaster—debris flow,was always induced by natural or man-made reasons when mountainous area was developed and built.The characteristics of debris flow are the occurrence of fast speed,large-scale,and causing great damage to objects within its threat range.There exists high mountains,steep slope,multi-stage superposition of fold structure,weathering and breaking of bedrock and strongly cut narrow and long valleys in northern region of Qinling Mountain.Besides,natural or artificial debris flow gullies are developed in the area affected by human activities.The toes of debris flow gullies are mostly human production and living area.Many traffic routes pass.Therefore risk assessment of debris flow is an effective non-engineering measure,and it has a certain degree of scientific guidance.In this paper,taking Gancha Gully of Huxian County as research object,development characteristics of debris flow basin and formation conditions of debris flow were fully analyzed by field investigation,visit at scene and data collection,dividing Gancha Gully into fresh water flooding area,forming area,passing by area and piling deposition area.And every area was investigated and analyzed.Fluid motion and dynamic character values of different debris flow burst cycles were calculated referring to rainstorm manual.The motion of Gancha Gully debris flow in different burst cycles was simulated by using FLO-2D.And the accumulation characteristics of Gancha Gully debris flow are analyzed.Based on the simulation results,its accumulation range of area is predicted,and provide basic data for vulnerability assessment.Finally,use Liu-Xilin's risk assessment theory of debris flow to evaluate Gancha Gully debris flow to get the risk and vulnerability of debris flow in different burst cycles.At last,it is suggested that Gancha Gully debris flow is moderate risk.And the necessity of the prevention and control of Gancha Gully debris flow is clarified,and put forward the prevention and control measures according to the actual situation in the gully.