The Whole Process Simulation And Risk Zoning Of Debris Flow In Cutou Gully Based On TRIGRS&Flo-2D

After the Wenchuan earthquake.The geological environment in the earthquake zone was damaged.Thus,the number of geological disasters in the earthquake zone increases.The debris flow disaster occurs suddenly,erupts frequently and has strong destructive power.Seriously threatening the life and property safety of local residents.Therefore,it is of great practical significance to study debris flow.Debris flow risk assessment is the premise of debris flow warning and engineering treatment.The result of risk zoning can comprehensively reflect the threat scope and damage degree of debris flow disaster.The intensity and scale of debris flow determine the risk degree of debris flow.Based on numerical simulation,the characteristics of debris flow source,movement and disaster scale were analyzed.This is an effective way to partition debris flow risk.In this paper,Cutou Gully,Miansi Town,Wenchuan County,was selected as the research object.Take the "8.17" Cutou mudslide disaster in 2020 as an example.According to the different distribution and initiation modes of debris flow,the provenance in Cutou Gully can be divided into landslide provenance,slope provenance and gully provenance.Based on TRIGRS and GIS,the range and distribution of provenance in Cutou Gully before "8.17" debris flow disaster were simulated and analyzed.The provenance reserves of Cutou Gully were calculated using the provenance reserves calculation formula.According to the relationship between debris flow source reserves,outflow quantity and outflow scale,the outflow quantity and outflow scale of "8.17" debris flow in Cutou Gully were determined.Based on Flo-2D,the motion process and threat range of debris flow disaster "8.17" were inverted.According to the simulation results,the outflow amount and scale of debris flow are determined.The results of the two methods are compared with the actual situation to verify the accuracy of the simulation results.Depending on rainfall,the risk range and movement characteristics of debris flow in Cutou Gully under different rainfall frequencies were simulated and predicted.According to the simulation results,the risk zoning of debris flow in Cutou Gully was carried out.The conclusions of this paper are as follows:(1)Take the "8.17" mudslide disaster of Cutou Gully as an example.Based on TRIGRS model and GIS.Combined with the rainfall conditions and geological conditions of the study area.The reserves and distribution of provenance in Cutou Gully before the "8.17" debris flow disaster were analyzed.According to the calculation results,the amount of debris flow and disaster scale are determined.(2)The process of debris flow disaster in "8.17" Cutou Gully was simulated by Flo-2D.Determine the debris flow threat area.The simulation accuracy is 84.5% by comparing the simulated accumulation area with the actual accumulation area.(3)By inverting the parameters of "8.17" Cutou Gully debris flow disaster.The movement characteristics and danger range of debris flow in Cutou Gully were predicted under the conditions of once 20 years,50 years and,100 years rainfall.(4)Based on different debris flow simulation results.The simulation results of debris flow in Cutou Gully are different.It rains once in 20 years,50 years,100 years.Combined with rainfall frequency,debris flow in Cutou Gully was divided into risk zoneings.High risk area,medium risk area,low risk area proportions are respectively62.4%,24.5%,13.1%.