Variation characteristics of extreme precipitation events in the Minjiang River Basin

Abstract: Based on the daily precipitation data from 1961 to 2016 of 26 stations in the Minjiang River Basin, the temporal and spatial variation characteristics of extreme precipitation events in the Minjiang River Basin were analyzed by Mann-Kendall nonparametric test and Morlet wavelet analysis.The results show that the extreme precipitation index has a strong inhomogeneity in the spatial distribution, the peak value appears in the middle reaches of the Minjiang River Basin,and the 1 day maximum precipitation is 92mm in Leshan, while the low peak value appears in the upper reaches of the Minjiang River Basin, and the average annual precipitation of the 1day in Wenchuan is only 21mm.The change rate of the 1 day maximum precipitation and the 5 days maximum precipitation are -1 .8mm/10a and 0.8mm/10. The upstream and downstream of the basin are weakly decreasing, while the middle reaches of the basin are weakly growing. The number of heavy precipitation days, extreme precipitation days and extreme precipitation are decreased slightly.The sudden changes of extreme precipitation in the Minjiang River Basin are mainly concentrated in 1960s and early twenty-first Century. after the mutation In 1960s,the intensity of extreme precipitation events increased significantly. After the mutation of twenty-first Century,the 1 day maximum precipitation decreased, but the cumulative precipitation increased.The oscillation cycle of the extreme precipitation index in the Minjiang River Basin was complex, among which the interdecadal oscillation period was the main oscillation. In 12a, 18a and 26a oscillations, the extreme precipitation events are mainly increasing after 2010, and the interannual oscillation is mainly 2-6 years, which has mainly been reduced in recent years.