关键词: 极端降水, 突变, 周期性, 风险概率, 四川

Abstract: According to the daily precipitation data from 1961 to 2009 and the disaster data from 1998 to 2007 of 141 meteorological stations in Sichuan, by using those methods like climate trend rate, Mann-Kendall check, complex Morlet wave, Gumbel distribution function, information diffusion theory, we analyzed the changing trend, mutation site and cyclicity of five extreme precipitation indices in seven subregions, and the spatial variability of the extreme daily rain and the flood loss risk about 50- and 100-year repeat period, obtained the main conclusions as below: the extreme precipitation was slightly increased and enhanced, and mutations happened at the early 1980s in the mountainous region of southwest Sichuan. They were also increased and enhanced in the northeast of Sichuan Basin and south of Western Sichuan Plateau, but not significant. While the trend in northwest and south of the basin and north of Western Sichuan Plateau was decreased and weakened. The frequency of the extreme precipitation tended to increase but its intensity became weaker in the middle of the basin. The most extreme precipitation indices shown a 25-year a long period and 6-9-year short period in most regions as well. From the 25-year long period, the recent extreme precipitation is being in a process of increasing and enhancing. By Gumbel distribution function, the maximum daily precipitation was fitted, the extreme area of it was in mountain areas around the basin and in the transitional zone of the plateau and basin. Three extreme centers are located in southwest, northwest and northeast of the basin, the daily precipitation with a 50-year return period is above 230 mm. The flood loss rate with a 50-year return period is about 38% in the most regions of the basin, it can reach 45% in northeast of the basin and 60% in the southwest of Guangyuan.

Key words: extreme precipitation, climate mutation, change cycle, risk probability, Sichuan