Abstract:Based on hourly precipitation data from the National Meteorological Information Center of the China Meteorological Administration, combined with the diversity of the terrain, the temporal and spatial characteristics of hourly precipitation, as well as characteristics of different types of Hourly Heavy Rainfall Event（HHRE） before（1992-2002）and after（2003-2021）the impoundment in Three Gorges Reservoir Area in the summer（from June to August）are analyzed. The results show that:（1）After impoundment, the precipitation and frequency decrease but intensity increases, while the change trends of the three are not significant. There is an obvious geographical distribution pattern for precipitation changes, with precipitation, frequency and intensity increasing in the central north of Three Gorges Reservoir Area, mostly located in the north of the Yangtze River, and the precipitation and frequency decreasing in the southwest while the intensity decreasing in the central south and northwest of Three Gorges Reservoir Area, mostly located south of 31°N.（2）There is a spatial distribution difference in the diurnal peak phases of precipitation, frequency, and intensity of hourly precipitation before and after impoundment, with the degree of difference being as follows: precipitation intensity>precipitation>precipitation frequency. After impoundment, the number of stations increases with increasing trend for precipitation, frequency and intensity, and the diurnal peak phases of precipitation and intensity have phase shift features in high altitude mountainous areas..（3）There is no significant change in the precipitation probability and proportion of hourly precipitation at various grades before and after impoundment. The precipitation probability shows the maximum（about 42%）at the grade of [0.1, 0.5）mm, and the minimum（about 1%）at the grade of ≥20 mm. The precipitation proportion shows the maximum（about 35%）at the grade of [1, 5）mm, the minimum（not more than 4%）at the grade of [0.1, 0.5）mm, and about 15% at the grade of ≥20 mm.（4）The daily variation characteristics of hourly precipitation after the impoundment are more obvious. The bimodal structures of precipitation and frequency of hourly precipitation at the grade of ≥20 mm are more prominent, while the peak time ranges of precipitation and frequency of hourly precipitation at other grades tend to expand, while the diurnal scale fluctuations of hourly precipitation intensity at each grade are more frequent.（5）Analysis of different duration types of HHREs shows that both before and after impoundment, the short-duration type of HHRE is the highest（more than 50%）, followed by medium-duration type（less than 30%）, and the long-duration type is the lowest（less than 20%）. The short-duration type of HHREs mostly start in the afternoon, while the other two types of HHREs mostly start at night. After impoundment, it is beneficial for HHRE maintenance, with a decrease in the proportion of short-duration type of HHRE and an increase in the proportion of medium-duration and long-duration types of HHREs, and the probability of the former starting at noon and afternoon increases, while the probability of the latter two starting in the morning increases.