Abstract: The key to hazard control and reduction for rainfall-triggered landslide is to identify the warning threshold scientifically. With Wuling mountain area as an example, historical landslide data and rainfall data from 1987 to 2011 were analyzed statistically using SPSS to reveal the relevance between rainfall and landslide event. Rainfall-triggered landslide in this region was mainly affected by the accumulated rainfall in the first three days of rainfall, and the effective coefficient of early-stage rainfall was only 0.6. Subsequently, based on the empirical threshold analysis model, the macroscopic I-D(intensity-duration) rainfall threshold curve for staged early-warning was established and verified through known rainfall landslide events. In view of the differences in scale, thickness, and slope gradient of landslides in the region, the I-D threshold curves corresponding to different geological conditions were built. Results unveiled that the rainfall threshold was evidently positively correlated with the scale and thickness of landslide, whereas slope gradient had an apparent susceptible interval (25° to 35°) where rainfall threshold reached the minimum. The conclusion offers reference for the forecast of rainfall landslide in Wuling mountain area and related areas.

Key words: rainfall-triggered landslide, staged early-warning, critical rainfall threshold, Intensity-Duration threshold curve, Wuling mountain area