Study on the return period of extreme precipitation in Liaoning Province based on the Compound Extreme Value Model

The study on the return period of extreme precipitation can improve the understanding of precipitation regularity, which is of great significance for preventing urban waterlogging, farmland waterlogging. To study the characteristics of the probability distribution of extreme precipitation in Liaoning Province, we use the daily precipitation data from 14 national meteorological observational stations in Liaoning Province during May to October of 1960-2020, and select the 98th percentile as the threshold of extreme precipitation. The Poisson-generalized Pareto compound extreme value model fits the extreme precipitation days and extreme precipitation amount and estimates the precipitation amount during the return period in Liaoning Province. The results show that the days with extreme precipitation and the extreme precipitation amount in Liaoning Province follow the Poisson distribution and the generalized Pareto distribution, respectively (both passed the statistically significant test of α=0.05). Extreme precipitation shows a gradual increase from the northwest to the southeast in Liaoning Province. The amount of extreme precipitation and the days of extreme precipitation are highest in the Dandong city. The Poisson-generalized Pareto compound extreme value model and the empirical frequency method can fit the precipitation amount during the return period very well. Under different return periods, the extreme precipitation amount in southeastern Liaoning Province is the highest.The extreme precipitation amount is relatively small in the middle of Liaohe River Basin, and is the smallest in the Northwest. The extreme precipitation amount in the mountainous areas of eastern Liaoning and the hilly areas of western Liaoning is higher than that in the plains of central Liaoning, and this spatial distribution is consistent for different return periods.