Rainfall Threshold Analysis of Landslides in Red Bed Areas Based on Rainfall Intensity and Duration: Pu’er as an Example
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Abstract:
Pu’er is located in the southwest of Yunnan Province. Magma rocks are widely distributed. The geological structure of this area is not only complex, but also a typical red bed landslideprone area. The characteristics and the rainfall threshold curve of raininduced landslide disasters can be obtained by using the Caine threshold curve, rainfall intensity and duration, clustering analysis and other methods, by means of the data of rainfall and landslids from 2009 to 2014 over Pu’er, so as to provide a theoretical basis for the prediction and warning of rainfallinduced landslides in the red bed areas. The statistical analysis indicates: (1) The landslide hazards in the study area mainly focus on the Ailaoshan Mountain group, Wuliang Mountain group and Lancang Mountain group, and belong to the corresponding fault zones. (2) Landslide hazards account for 77.1% of the total, occurred most frequently from July to September. (3) Landslide hazards can be divided into the shortterm heavy rainfall type, midterm weak rainfall type and longterm weak rainfall type. The statistical analysis shows that there are 40 landslides without significant correlation with rainfall (0.7%). (4) Using the improved Caine model, it can be obtained that the rainfall threshold curves of landslides can be divided into four categories in the study area: I=85D-0.874, I=45D-0.811, I=27D-0.782, and I=12D-0.774. The minimum threshold is higher than the global threshold of Guzzetti, but lower than that of Caine, and the maximum threshold is higher than the threshold of landslides induced by typhoon rainfall in Fujian.