RETURN PERIOD STATISTICS OF EXTREME RAINFALL AND APPLICATION TO LANDSLIDE PROBABILITY ANALYSIS

The occurrences of landslides usually have a good relationship with rainfall, especially with extreme rainfall events. Based on the theory of Gumbel Extreme Distribution, rainfall precipitation of Badong county in the Three Gorges Reservoir from 1990 to 2006 was statistically analyzed in the paper. Some special extreme values and distribution curves for rainfalls in flood seasons were obtained, including the maximum accumulative daily rainfall, the greatest accumulation rainfall. It is concluded that: with the increase of return period, the accumulation rainfall of one rainfall course can increase; with the increase of rainy days, the accumulation rainfall of one rainfall event with different return period can increase. And longer the return period is,greater the rainfall can be. Based on the above conclusions, the results are respectively used to re-active and newly active landslides trigged by rainfall. The method of probability of the landslide is further discussed in this paper.