Based on hourly precipitation data from 96 meteorological stations during the flood season from 1980 to 2018 in Hunan Province, the occurrence frequency and contribution rate to the total precipitation amount were used as important indicators, and the spatialtemporal evolution characteristics of precipitation structure in Hunan Province during the flood season were analyzed. The results are as follows: (1) The occurrence frequency of rainfall events decreased by power function with increasing durations, while its contribution rate to the total precipitation amount of rainfall events increased linearly with increasing duration. The occurrence frequency of short duration rainfall event was high, while its contribution rate to the total precipitation amount was low. The occurrence frequency of long duration rainfall event was low, but contribution rate to the total precipitation amount was high and long duration rainfall event was the main body of precipitation in flood seasons. Both the occurrence frequency and contribution rate to the total precipitation amount of short duration rainfall events  were higher in southern Hunan than in northern Hunan, while the occurrence frequency and contribution rate to the total precipitation amount of long duration rainfall events were higher in northern Hunan than in southern Hunan. (2) In the past 10 years, both the occurrence frequency and contribution rate to the total precipitation amount of short duration rainfall events increased linearly, while the occurrence frequency and contribution rate to the total precipitation amount of long duration rainfall events decreased linearly. (3) Occurrence frequency of all rainfall events decreased by power function with increasing precipitation levels, while contribution rate to the total precipitation amount increased linearly with increasing precipitation levels. Although the occurrence frequency of torrential rainfall event was low, while it was the main contributor to precipitation during the flood season. The occurrence frequency and contribution rate to the total precipitation amount of light to moderate rainfall events were generally higher in southern Hunan than in northern Hunan, while the occurrence frequency and contribution rate to the total precipitation amount of heavy to torrential rainfall events were higher in northern Hunan than in southern Hunan.  (4) The interannual variation of occurrence frequency of light to heavy rainfall events was not significant, but the occurrence frequency of the torrential rain event increased significantly, while the interannual variation of contribution rate to the total precipitation amount of light rainfall events was not significant, but for moderate rain to heavy rainfall event it showed a significant downward trend, and contribution rate to the total precipitation amount of torrential rainfall events showed a significant upward trend.

In recent years, the rainstorm occurred frequently in Zhuzhou of Hunan Province, which caused increasingly serious urban water-logging, and the rainstorm parameters of drain and flood control design had changed obviously. Based on minutely precipitation from 1963 to 2017 at Zhuzhou weather station, the samples of annual maximum precipitation with sixteen durations were selected by using the moving average method, and the variation characteristics of designed rainstorm intensity and pattern before and after climate abrupt change in Zhuzhou were discussed. The results show that rainstorm days and annual maximum precipitation had an obvious abrupt change in 1983 in Zhuzhou of Hunan Province. After the mutation, rainstorm days increased and rainstorm intensity strengthened, which caused the increase of extreme precipitation events in Zhuzhou. Before the mutation, the change trends of annual maximum precipitation with different durations were inconsistent and non-significant, while they showed obvious increasing tendency after the mutation, and the precipitation with duration 120 minutes and above passed the significance test. The precipitation of rainstorm with different durations increased under different recurrence periods after the mutation, and the difference of precipitation before and after the mutation increased with increase of recurrence period and extension of duration. The position and precipitation of rain peak for short-time and long-time rainstorm pattern moved forward and increased after the mutation, respectively, which partly explained why the water-logging was frequent in Zhuzhou in recent years.

Based on the precipitation data of 6 automatic stations during 2013-2017 in the Yigeziya River Basin in Aktao county of Xinjiang and 7 national meteorological stations during 1961-2017 around the basin, the function relation between flood depth and rainfall was constructed by using FloodArea model in order to explore the threshold of disaster-causing critical rainfall under different recurrence periods of mountain flood. The hourly inundated area and inundated depth were simulated by hydrodynamic model. Combined with the disaster-affected factors (population distribution, GDP, land-use types) in the study area, the flood disaster risk zoning of the basin was completed. The results show that the middle and lower reaches of the basin was the high risk area of flood disaster risk, while the relatively high altitude area in the upper reaches of the basin was the low risk area of flood inundation.