Research On Characteristics And Control Measures Of Taohua Gully Debris Flow In Kangding County

Taohua gully is located in Kangding County,Sichuan Province,with frequently historical debris flow occurrences,causing severe damages to local settlement.Since 2002,no large-scale debris flow has occurred in this gully except that floods mobilized during the rainy seasons.Considering the pre-existing dangerous rocks,and plenty of source materials,combined with the steep longitudinal slope of the main channel,rainfall-induced debris flows are prone to occur and pose a potential hazard to the villagers.Taohua gully has an area of 4.737 km~2,a longitudinal slope of the main channel of 562.5‰.Unfavorable geological phenomena are ubiquitous in the catchment,with an immense amount of waste slag from engineering construction deposited in the gully outlet.Based on collected data and field investigation,we determined the type,location,volume and failure mode of source materials and revealed the characteristics and mechanisms of debris flow.Under the jointed effect of terrain,rainfall and source material supply,two types of debris flow,involving valley-type and slope-type will formed during the debris flow mobilization.Eventually,waste slag in the gully outlet will be eroded by the fluid,inducing an amplification of the mobilized volume of debris flow.We calculate the kinetic parameters based on the above mentioned characteristics.Then,using the CFX software,the propagation,runout process and accumulation of the debris flow at the outlet were simulated under the different rainfall return records(P=5%,2%and 1%).The discharge,velocity and flow height are monitored.The results suggest that a serious impact can be caused by debris flow of P=2%and P=1%.Consequently,control measures are proposed based on the simulation results and kinetic parameters.