Research on the Variation Trend of Regional Extreme Precipitation in Anyang Based on ITA and ITA-CB Methods

To quantitatively analyze the changing characteristics of extreme precipitation in the Anyang area at the eastern foot of the Taihang Mountains, the innovative trend analysis method (ITA) and the improved ITA method (ITA-CB) were used to analyze the trend changes and spatial distribution characteristics of extreme precipitation indices in the Anyang area from 1958 to 2023 at both station and regional scales. The results show that: ①The trend consistency of the ITA method with the linear regression method and the Mann-Kendall test is 86.7% and 78.8% respectively, which verifies the applicability of the ITA method in extreme precipitation analysis and provides a powerful supplementary tool for hydro-climatic trend analysis. ②The change of regional total precipitation is mainly driven by heavy precipitation events, and the total amount of extreme precipitation is mainly concentrated in a few of the most intense precipitation events, which highlights the decisive role of extreme events in the annual water balance. ③The variation trends of most extreme precipitation indices show regional consistency, but there are differences between different stations. The hilly and plain areas have their own special climate response synchronicity, and there is a climate feature of “alternating drought and flood”. ④The intensity of extreme precipitation events and their contributions to total precipitation in the hilly area show an increasing trend, while the opposite change is true in the mountainous area. ⑤The frequency and total amount of extreme precipitation events in the mountainous area are greater than those in the hilly and plain areas, and the intensity of extreme precipitation events in the hilly area is greater than that in the mountainous and plain areas. ⑥In the region, PRCPTOT and R95p show an upward trend in the low-value and high-value areas, while a downward trend in the middle-value area. This structural feature of “increase at both ends and decrease in the middle” indicates that the polarization trend of precipitation in the region will intensify in the future, suggesting that both drought events and extreme rainstorm events may increase simultaneously.