Abstract:
Based on the hourly precipitation data from 2017 to 2021 to calculate and filter out the events of the abrupt heavy rainfall. The occurrence frequency, average process rainfall, average duration and maximum hourly rainfall of the abrupt heavy rainfall were selected to characterize the danger degree of the abrupt heavy rainfall. The danger degree model of the abrupt heavy rainfall was constructed by calculating the grey correlation degree of each factor as the weight value. The result shows that: (1) The abrupt heavy rainfall in Sichuan Basin mainly occurred from May to September, accounting for more than 90% of the total frequency. (2) The start time of the abrupt heavy rainfall was mainly concentrated from 15:00 to 6:00 of the next day, accounting for more than 70%, reaching the peak during the period from 18:00 to 21:00. (3) The abrupt heavy rainfall occurred in all range of Sichuan Basin, but the frequency was not high, and the high frequency areas were mainly distributed in Ya’an and Mianyang. (4) In northern Sichuan Basin, the abrupt heavy rainfall had the characteristics of low frequency, long duration and large average process rainfall, while in southwestern Sichuan Basin, the abrupt heavy rainfall had the characteristics of high frequency, short duration and low average process rainfall. (5) In July and August, the high-risk areas of abrupt rainfall in Sichuan Basin were widely distributed, mainly in the northwest, southwest and central regions. In May, June and September, the high-risk areas were mainly distributed in the southeast of Chongqing and the north of Sichuan Basin.