Risk Assessment Of Debris Flow In Dechang County

Dechang County is located in the southwest of Sichuan Province,the geological environment is complicated,and the debris flow disaster seriously affects the local development.Based on the detailed survey projects,Dechang county geological disaster,according to the data of field survey and data analysis of natural geography and debris flow disasters in the study area development characteristics,distribution characteristics and influence factors of selecting and debris flow disaster is closely related to the nine research area of debris flow risk evaluation index to construct the evaluation index system,using different evaluation model to carry on the risk assessment,The AUC values of ROC curve were compared to select the optimal evaluation model for zoning and put forward disaster prevention suggestions.The following research results have been obtained:(1)Through collecting and sorting out the natural geography and geological environment conditions of Dechang County are as follows: abundant rainfall,developed water system,severe terrain cutting,wide elevation difference,diverse topography and landform,complex stratum lithology,well-developed faults,and intense human engineering activities.(2)By analyzing the characteristics and causes of debris flow disasters in the study area,it is concluded that debris flow disasters are mainly distributed in 15 towns and villages of the whole county,among which Laoyan and Cida debris flow disasters are the most distributed,reaching 17 and 15 respectively.The highest frequency of debris flow disasters occurs in July and August.There are many furrows and branches in the area.Large longitudinal slope drop;Strong tectonic movement;Rock mass structure is broken;More loose deposits.Landform and other factors have great influence on the development of debris flow disasters.(3)Slope,NDVI,formation lithology,gully density,topographic relief,distance from fault,rainfall,distance from river system and human engineering activities were selected as evaluation indexes to construct the evaluation index system of debris flow risk.According to the AUC value of ROC curve,it can be known that the informationLogistic coupling model is the optimal evaluation model.Watershed units are used to partition the risk of the evaluation results of the information-Logistic coupling model.They are high,high,medium,low and low risk areas respectively.According to the statistics,the area of low and relatively low risk areas is 64.43% of the total area,while the number of debris flow disaster points is only 16.3% of the total debris flow disaster points,indicating that most areas in the study area are less affected by debris flow disasters.The area of high and high risk areas is 20.79% of the total area,but the number of debris flow disasters is 63.04% of the total debris flow disasters,indicating that debris flow disasters are concentrated in the study area.There are obvious differences among areas with different risk levels.Debris flow mainly develops in high and high risk areas,which is consistent with the actual situation in the study area.According to the results of risk zoning of debris flow disaster,scientific suggestions are provided for the prevention and control of debris flow disaster in Dechang County to promote the sustainable development of economy and environment in Dechang County.