Early Warning Of Rainfall Induced Landslide Disaster In Dazhou City

Dazhou City,due to its special landform and heavy rainfall,has caused frequent landslides,which has caused great damage to the people's life and property and living environment,and the prevention and warning work is arduous.In this paper,rainfall is the main factor of landslide occurrence.The research on the early warning of landslides caused by rainfall in Dazhou city is carried out in order to provide reliable rainfall landslide warning model to minimize the loss caused by landslide disasters.According to the data of rainfall,landslide and geological environment in Dazhou city from 2004 to 2019,the correlation between rainfall and landslide is analyzed;The paper uses GIS software and logistic regression model to evaluate the landslide disaster prone in Dazhou City,and analyzes the distribution characteristics of Dazhou landslide;Based on the I-D threshold model(Rainfall intensity-Rainfall duration),the author analyzes the threshold of rainfall triggering landslide in Dazhou city based on the administrative boundary,landslide prone division and evaluation factor classification of the districts and counties,and studies the rainfall threshold and characteristics of the landslide in Dazhou;Based on the results of susceptibility assessment(H),the model of the prediction of the landslide induced by rainfall(T=?H+?Y)is established by combining the probability model of geological disaster causing factors(Y).The model of warning with the empirical value as the weight constant and the warning model after the weight constant(?,?)is modified by entropy weight method is compared and studied,and the warning model suitable for the rainfall induced landslide in Dazhou city is given.The conclusions are as follows:(1)The rainfall in Dazhou city is mainly from May to September,accounting for 73.00%of the total rainfall,and the landslide is concentrated in July September,accounting for 73.46%of the total landslides.According to the correlation analysis of 748 landslide events,6 rainfall factors,such as the rainfall on the same day,the first day before the landslide,and the 5th day,are the early rainfall factors that induce landslide occurrence.(2)The paper selects 8 evaluation factors,including slope,height difference,NDVI,annual rainfall,land use type,distance from river,stratum lithology and landslide point density as the evaluation factors of landslide vulnerability in Dazhou city.Through logistic regression model,the results of the evaluation area of landslide vulnerability in Dazhou city are obtained.Dazhou city is divided into four types of areas with different landslide prone degrees,namely high prone area,middle prone area,low prone area and non prone area.Among them,the high risk areas are mainly distributed in the East and west sides of Dazhou city.(3)The analysis of rainfall threshold model shows that the smaller the threshold of rainfall triggered landslide disaster,the more likely landslide will occur in the land.According to the administrative boundary of districts and counties,the rainfall threshold is from high to low,which is Kaijiang County,Dazhu County,Wanyuan City,Xuanhan County,Dachuan District,Tongchuan District and Quxian county;Based on the classification of landslide prone zoning,the rainfall threshold is classified from high to low,which are not easy to occur,low prone,medium and high prone;Based on the classification of risk assessment factors,the areas with low rainfall threshold are mainly distributed in areas with the landform features of elevation difference greater than 40 meters,slope greater than 11 degrees,vegetation coverage less than0.33,soft lithology,less than 1km from the river and farmland.(4)In the early warning model research,based on the evaluation area of landslide vulnerability,the weight constant of probability model of geological disaster factors is improved by entropy weight method,and the rainfall induced landslide warning model is T=0.417H+0.583Y(T is the warning value).The results show that the entropy weight method is more reliable than the empirical one.Finally,according to the research content and relevant regulations on geological disaster prevention,the early warning procedure is formulated and the measures for the prevention and treatment of landslide disaster in Dazhou city are given.